JP4146196B2 - Composite optical device and manufacturing method thereof - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a micro-optical element including a light-emitting element, and more particularly to an apparatus technique including an optical element that generates high-quality micro-parallel light. Here, the light emitting element includes not only the light source itself but also an emission end face when a light beam is incident on an optical fiber or the like.
Application fields include general application products that use high-quality light beams, such as light transmission light sources, semiconductor laser (hereinafter simply referred to as LD) printers, optical disk system pickup light sources, and optical projector displays that sweep LD light. .
[0002]
[Prior art]
A conventional optical element controls light from an LD or the like via a lens or mirror having a size on the order of mm. However, as optical transmission and the like become versatile, demands for high density, miniaturization, high accuracy, and low cost are increasing. Therefore, with the development of OPT-MEMS that combines micromachining technology and optics, micro optical elements such as microlenses, micromirrors, and optical switches based on MEMS technology that handle light in the order of μm have been developed.
[0003]
Since such a micro optical element has a lens surface or a mirror surface in the order of μm, a light source having such a size is required. One solution that meets this demand is parallel light with a diameter on the order of μm. If it is parallel light, the distance of the order of mm is transmitted without divergence, and there is no need for complicated alignment of a large lens, and the consistency of switching and mirrors is high. Moreover, since the diameter of the optical fiber and the size of the high-speed compatible PD (photodiode) are on the order of μm, the versatility of the minute parallel light is high.
[0004]
In general, when shaping a light beam emitted from a light source such as an LD, a lens is disposed outside a can on which the LD is mounted. In this case, the lens has a diameter of several millimeters because it is several millimeters away from the light emitting point of the LD and has a light divergence angle of about 40 °. In addition, the mounting of the lens is often performed manually while observing the light emitting spot of the LD, and the manufacturing cost is increased, and the mounting tolerance is set to be very large. Such a large tolerance causes a large aberration in the light beam of the completed composite optical device after mounting, and cannot be said to be a high-quality light source that will be required in the future.
[0005]
On the other hand, an attempt has been made to mount the lens directly on the inside of the can and on the stem of the LD (the substrate on which the LD is fixed). A lens can be mounted at a distance of several tens of μm in the vicinity of the light emitting point of the LD, and the lens can have a diameter of several tens to several hundreds of μm. A lens having such a size is manufactured as a microlens by a semiconductor process or the like. A lens manufacturing method has been established and it is easy to form an array, and there are great expectations for its practical use, and many studies have been made (for example, Patent Document 1, Patent Document 2, Patent Document 3, Patent Document 4, Patent (Ref. 5). However, many problems remain in mounting the microlens and the light emitting element, and the mounting tolerance is still large.
[0006]
A method has also been studied in which the end face of the microlens is brought into contact with the LD so that it can be simply mounted and the cost associated with mounting is reduced. (Patent Document 6) is one of them. In this case, the lens end face is in contact with the LD end face. The microlenses shown there are formed using a heat drawing method after forming a lens shape by grinding. Further, in this method, in order to obtain a desired distance from the lens, an appropriate spacer is formed by the same method and is integrated by bonding. For this reason, the shape cost of these spacers is included, and the manufacturing cost increases. In this method, it is difficult to create the spacer and the lens integrally, and the above-described joining method is inevitable.
[0007]
On the other hand, there is a refractive index distribution lens as a flat lens. This lens is obtained by diffusing metal ions such as thallium on a glass substrate, and has a flat surface and can be in close contact with the light emitting element. However, this graded index lens is inferior in quality to ordinary lenses, such as increased wavefront aberration and accuracy of light refraction. For this reason, it cannot be a composite optical device having a high-quality light source (see, for example, Patent Document 7).
[0008]
[Patent Document 1]
JP 2001-185792 A
[Patent Document 2]
JP-A-5-236216
[Patent Document 3]
JP-A-6-160605
[Patent Document 4]
JP-A-2-222589
[Patent Document 5]
JP 2001-021771 A
[Patent Document 6]
US Patent No. 6078437
[Patent Document 7]
JP-A-6-13699
[Patent Document 8]
JP-A-11-177123
[Patent Document 9]
JP 2000-280366 A
[Patent Document 10]
JP 2000-349384 A
[Non-Patent Document 1]
O plus E February 2001 issue P210
[0009]
[Problems to be solved by the invention]
Provided is a method for realizing mounting of a light source such as an LD and an optical element for shaping the light beam with high accuracy and low cost, and a composite optical device capable of obtaining a high-quality light beam with small aberration. The problem is described in detail below.
[0010]
Here, the definition of the surface of the light-emitting element is extended to “surface emitting light into the air”. For example, in the case of an optical fiber or the like, an element in which an optical fiber and an LD are combined, such as an LD coupled to “one end face”, is also defined as a light emitting element. In this case, the “plane of the light emitting element” or “light emitting end surface” refers to the “other end surface” of the end surfaces of the optical fiber to which the LD is not coupled. Conventionally, studies have been made to mount a lens with high accuracy on the plane of the light emitting element.
[0011]
For example, there is a method in which a photolithographic process is directly applied to an end face of an optical fiber, and the end face of the fiber is processed into a microlens shape (see, for example, Non-Patent Document 1). However, wavefront aberration due to the surface roughness (hereinafter referred to as roughness) of the microlenses increases, and there remains a problem as a composite optical device that should be a high-quality light source.
According to the above invention, the optical member of the microlens and the light emitting element plane can be in contact with each other, but the mounting accuracy is lowered due to the poor surface properties of the respective contact surfaces.
[0012]
FIG. 11 is a diagram for explaining a conventional form of mounting an LD and a microlens.
In the conventional LD and microlens mounting, the optical member of the microlens and the cleavage surface of the LD are not in contact with each other. That is, as shown in FIG. 11, the apex of the microlens protrudes from the plane of the optical member, and it is necessary to secure a gap S through an appropriate spacer in the flat portion (see Patent Document 5). ).
[0013]
In order to avoid hitting the lens portion of this spacer, it was necessary to perform very difficult machining such as a concave portion having a diameter of several hundred μm. Also, because of the minute shape, it is impossible to polish, and it is made by machining such as milling, and the surface remains rough, making it difficult to mount with high accuracy. Therefore, the accuracy is several μm, and the tolerance is large. Moreover, the stem which performs such a process becomes very expensive and jumps up as a cost. However, in the present invention, the term “microlens” refers to a curved surface refractive lens, and does not include a gradient index lens.
[0014]
Conventionally, when a microlens is mounted on an LD, a method of mounting by observing a light emitting spot is generally used, which increases the manufacturing cost. As another method, there is a method of aligning the alignment mark with a stem on which an LD is mounted. However, since the mounting tolerance between the LD and the stem is included, the accuracy is lowered. Therefore, it is not possible to obtain a light beam with good quality.
[0015]
As shown in the conventional example, as a method of fixing the microlens, a method of applying and curing a UV curable resin on the side surface of the optical member of the microlens is taken. This method has a problem in bonding strength because there are few surfaces to be bonded. Since the tolerance of the distance between the lens and the light emitting element such as the LD is about several μm, it is not allowed to shift due to disturbance such as slight vibration. Therefore, high joint strength is required.
[0016]
In the conventional microlens manufacturing method using the reflow method, the shape of the lens is limited to a spherical surface. Due to the spherical surface, the aberration in the completed composite optical device becomes large due to the wavefront aberration on the lens surface.
[0017]
When the microlens is a convex lens, light rays are incident on the lens surface at a shallow angle at the edge of the lens. That is, the incident angle with respect to the lens is increased. The reflection of light depends on the incident angle, and the larger the incident angle, the higher the reflectance. The relationship will be described with reference to FIG. In the figure, however, the angle is expressed with respect to the tangent of the surface. The angle of incidence with respect to the normal and the angle with respect to the tangent are in the relationship of the covariance.
FIG. 12 is a diagram for explaining a difference in incident angle with respect to a tangent line between a convex surface and a concave surface.
FIG. 12a shows a state in which light enters the periphery of the convex lens. θ1 represents an incident angle of incident light with respect to a tangent to the lens surface.
FIG. 12b shows a state in which light enters the periphery of the concave lens. θ2 represents an incident angle of incident light with respect to a tangent to the lens surface. In both cases, light rays after refraction are omitted. As can be seen from the figure, θ2> θ1. Therefore, the loss of light is greater on the convex surface than on the concave surface.
As much as possible, it is desirable to reduce the angle of incidence with respect to the normal and make a lens with low reflection.
[0018]
Since there are two interfaces with the light emitting element surface and the microlens surface, there is reflection at each interface. Reflection causes problems such as a reduction in noise and coupling efficiency. Further, when the plane of the light emitting element has roughness, light scattering occurs on that plane, and the optical coupling efficiency is lowered.
Microlenses have certain limitations on the height of the lens due to manufacturing problems. Therefore, a lens with a high NA could not be made.
[0019]
In the composite optical device, as a mounting method, it is necessary to accurately align two axes other than the optical axis (when the optical axis is the Z axis, the X axis and the Y axis). It is difficult to align the two axes at the same time, increasing the manufacturing cost.
[0020]
[Means for Solving the Problems]
  In order to solve the above-mentioned problem, in the invention according to claim 1, in the composite optical device in which the light emitting element and the optical member including the optical element are integrated, the optical member isPolished surfaceA first surface and a second surface facing the first surface, wherein the optical element is formed by processing a part of the first surface, and an emission end of the light emitting elementOn the faceThe first surface of the optical member is in contact with the optical member.
[0021]
  According to a second aspect of the present invention, there is provided the composite optical device according to the first aspect.,in frontThe optical member has a function of supporting a constant distance between the light emitting element and the optical element.
  Claim 3In the invention described in claim 1,Or 2In the composite optical device according to the item 1, a concave portion is formed on the first surface of the optical member, and the optical element is formed on the bottom of the concave portion.
[0022]
  Claim 4In the invention described in claim 1, claim 1 is provided.3In the composite optical device according to any one of the above, the light emitting element is a semiconductor laser.
  Claim 5In the invention described in claim 1,4In the composite optical device according to any one of the above, an optical element is also formed on the second surface of the optical member.
  Claim 6In the invention described in claim 1,5In the composite optical device according to any one of the above, the optical element is a microlens.
[0023]
  Claim 7In the invention described inClaim 6In the composite optical device described in (1), the optical surface of the microlens is an anamorphic surface.
  Claim 8In the invention described in claim 1,5In the composite optical device according to any one of the above, the optical element is a cylindrical lens.
  Claim 9In the invention described inClaim 8In the composite optical device according to the above, the cylindrical lens has an action direction aligned with the major axis direction of the elliptical shape of the cross section of the light beam on the first surface of the optical member, and the elliptical shape of the cross section of the light beam on the second surface. The action direction is aligned with the minor axis direction.
[0024]
  Claim 10In the invention described in claim6 to 9In the composite optical device according to any one of the above, the height of the apex of the optical element on the first surface is lower than the first surface of the optical member.
  Claim 11In the invention described in claim6 to 9In the composite optical device according to any one of the above, the lens surface of the optical element on the first surface is a concave surface.
[0025]
  Claim 12In the invention described in claim6 to 11In the composite optical device according to any one of the above, the cross section having the optical power of the optical surface of the optical element is a non-circular surface.
  Claim 13In the invention described in claim1 to 5In the composite optical device according to any one of the above, the optical element is an optical wedge.
  Claim 14In the invention described inClaim 13In the composite optical device according to the above, the incident angles of all the light beams incident on the first surface are more than the angle corresponding to the maximum deflection angle of the triangular prism formed by the optical surfaces of the first surface and the second surface. The optical surface is formed to be large.
[0026]
  Claim 15In the invention described inClaim 14In the composite optical device described in (1), the direction of action of the optical wedge is aligned with the direction of the smaller divergence angle of the light beam emitted from the semiconductor laser.
  Claim 16In the composite optical device according to claim 14, in the composite optical device according to claim 14, a triangular prism in which incident angles of all light beams incident on the first surface are formed by the optical surfaces of the first surface and the second surface. The optical surface is formed so as to be smaller than an angle corresponding to the maximum deviation angle.
[0027]
  Claim 17In the invention described inClaim 16In the composite optical device described in (1), the direction of action of the optical wedge is aligned with the direction in which the divergence angle is larger in the luminous flux emitted from the semiconductor laser.
  Claim 18In the invention described in claim1 to 5In the composite optical device according to any one of the above, the optical element is a circular diffraction grating.
  Claim 19In the invention described in claim1 to 18In the composite optical device according to any one of the above, the space in which the optical element does not exist is filled with a transparent member having a refractive index different from that of the optical member.
[0028]
  Claim 20In the invention described inClaim 19In the composite optical device described in the item 1, the refractive index of the transparent member is larger than the refractive index of the optical element.
  Claim 21In the invention described inClaim 19In the composite optical device according to the item 1, the light emitting element is an optical fiber end face, and the refractive index of the transparent member is approximately equal to the refractive index of the light emitting element.
  Claim 22In the invention described in claim 1,21In the composite optical device according to any one of the above, a groove is formed on the first surface of the optical member, and an adhesive is injected into the groove.
[0029]
  Claim 23In the invention described in claim 1,Thirty-twoIn the composite optical device according to any one of the above, an alignment mark is formed on the optical member.
  Claim 24In the invention described inClaim 23A manufacturing method for manufacturing the composite optical device according to claim 1, wherein an alignment mark of the optical member is aligned with a mark on a plane of the light emitting element, and an emission end of the light emitting elementSurface and saidIt is characterized by a method for manufacturing a composite optical device that abuts and joins a first surface of an optical member.
[0030]
In the present invention, an optical element such as a microlens is manufactured by a manufacturing method using a gray scale mask, thereby enabling highly accurate passive alignment based on the polished surface of the optical member.
[0031]
A micro lens manufactured using a semiconductor process is generally used by a reflow method or the like, but in the present invention, a manufacturing method using a gray scale mask is used. However, the present invention is not limited by this manufacturing method.
An optical element made of a gray scale mask is an optical element formed on a polished plane, and the area other than the element is a plane having a highly accurate surface property.
[0032]
As gray scale masks, there are masks used for photolithography in which gradations are expressed with fine dots having transmittances of 1 and 0, and those in halftones. By gradation expression, bright part and dark part are created, and this is exposed to photoresist, so in the case of positive resist, the dark part is high, the bright part is low, and the height expression includes the intermediate height. The resist shape thus obtained can be obtained. By devising the mask shape in this way, the resist can be processed into a three-dimensional and arbitrary shape. Details of the gray scale mask manufacturing method are described in Patent Documents 8 and 9, and the like.
[0033]
By utilizing this arbitrary shape manufacturing technique, it becomes possible to make a microlens whose lens is concave from the reference of the quartz substrate. As a result, the reference surface protrudes from the microlens to the LD side, and can be mounted in a state in which the reference surface is in contact. Further, as will be described later, an inclined surface or a diffraction grating can be formed in a portion away from the LD.
[0034]
The reference surface of the optical member of the microlens is processed by polishing, and if the accuracy is high, it is on the order of several nm. Further, the cleavage plane of the LD is also formed according to the crystal plane, so that it is surfaced with very high accuracy. By abutting these two surfaces, mounting with very high accuracy becomes possible. Further, the surface of the submount can be polished similarly to the quartz substrate. As a result, the LD and the submount can be mounted on the same surface position while maintaining a high degree of parallelism, and a quartz polishing surface is provided on the LD cleavage surface and the submount polishing surface in which the parallelism is maintained. Abutment mounting is possible.
[0035]
Embodiment 1
FIG. 1 is a side view showing the configuration of Embodiment 1 of the present invention.
FIG. 2 is a front view showing the configuration of the first embodiment of the present invention.
1 and 2, reference numerals 1 and 1 'are microlenses, 2 is an optical member, 3 is an LD, 4 is a submount, 5 is a UV curable resin injection groove, 6 is a stem, 7 is a UV curable resin, and 8 is an LD. Epitaxial surface 9 indicates an alignment mark.
An optical member 2 made of a quartz substrate or the like having microlenses 1 and 1 ′ is in contact with a submount 4 that holds the LD 3. A UV curable resin injection groove 5 is formed in the optical member 2 and UV curable resin is injected.
[0036]
The microlenses 1 and 1 ′ are formed on the front and back of the optical member 2 with the optical axes aligned. A surface on which the microlens 1 is manufactured is a first surface. The first surface is polished in advance. After producing the microlens 1 on the first surface, if necessary, another microlens 1 'is produced by aligning the optical axis with the second surface facing the first surface. Since the quartz substrate is transparent at this time, the same lens alignment mark can be used and can be performed with high accuracy. The accuracy is on the order of several hundred nm by using a microscope.
[0037]
In addition, a large number of microlenses can be taken from one wafer, and since this alignment is performed for each wafer, the manufacturing cost is very low. For this reason, the cost increase by forming microlenses on both surfaces is small. However, when the objective can be achieved by the microlens 1 alone, the microlens 1 ′ can be omitted. In that case, at least the surface of the second surface through which the light beam is transmitted is formed as an optically smooth surface. The same applies to the following embodiments other than the microlens. The term “optical surface” as used herein refers to a surface that transmits an effective light beam without scattering, and includes a simple plane that gives an optical action to a light beam that travels straight.
[0038]
The shape and divergence angle of the light emitting part of the LD are greatly different in the vertical direction and the horizontal direction. That is, the shape of the light emitting portion is long in the horizontal direction, and the vertical direction is only a few tenths of the length in the horizontal direction. However, the divergence angle is related to the interference of coherent light, and the divergence angle in the horizontal direction is about a fraction of the divergence angle in the vertical direction. The LD has a large individual difference, but the emitted light beam has a circular cross-sectional shape, that is, a light profile at a position of about several μm to 10 μm from the emission end face, and beyond that, the light profile becomes a vertically long elliptical shape. Become.
[0039]
Various distances from the light emitting end face of the LD 3 light of the optical element of the present invention can be selected, but in order to avoid the influence of individual differences as much as possible, the position where the light profile becomes a vertically long ellipse is selected. Is good.
[0040]
On the other hand, there is an anamorphic lens in which the curvature of the central section in the vertical direction and the central section in the horizontal direction are different. Since this lens has different power in the vertical and horizontal directions, the divergence angle in each direction can be changed individually. The purpose of this embodiment is to shape an elliptical light beam emitted from the LD into a perfect circle. By making at least one of the optical surfaces of the two lenses an anamorphic lens surface, the divergent light emitted from the LD is converted into a perfect circular parallel light.
[0041]
A spherical lens is generally excellent as a lens that accepts light from any direction, but the light source to which the present invention is applied is a single wavelength LD, and the incident angle with respect to the lens system as an optical element is fixed. In the target case, by selecting an appropriate aspherical surface as the optical surface, it is possible to remove various aberrations and obtain a very high quality light beam. In this embodiment, an anamorphic lens is used. This is circular in the shape of the longitudinal section and the transverse section, but has a different curvature and cannot be called a spherical surface. However, what is called the aspherical surface is different. That is, it means that the shape of the longitudinal section or the transverse section having optical power is non-circular.
[0042]
As shown in FIG. 2, the alignment mark 9 is formed to coincide with the corners of the epitaxial surface on the lower surface of the LD 3 and the cleaved surface of the side surface.
The alignment mark 9 is simultaneously placed in the gray scale mask of the microlens during photolithography. Thereby, the alignment mark 9 can be made with a tolerance in mask manufacturing, and the accuracy thereof is several hundred nm.
[0043]
By mounting the corners of the LD 3 in contact with the alignment mark 9, the mounting accuracy by microscopic observation is remarkably increased. If it is not in close contact, it is necessary to position each alignment mark surface while alternately focusing and observing using the focus function of the microscope, and mounting due to other uncertain factors such as the parallelism of the microscope. Accuracy is reduced. The alignment method is described below according to each axis. However, each axial direction follows the definition of FIG.
[0044]
<Alignment in the Y-axis direction>
The LD 3 shown in FIGS. 1 and 2 is a junction down, with the upper side being a member back surface and the lower side being an epitaxial surface. The distance between the epitaxial surface and the light emitting point is designed and manufactured with an accuracy of the order of several tens of nanometers. For this reason, it is possible to obtain an accuracy of 1 μm or less by aligning the corners of the LD 3 with the alignment marks 9 formed on the optical member 2 in close contact with each other.
[0045]
<X-axis alignment>
The distance from the light emitting point to the side surface of the LD 3 varies depending on the individual difference of the LD. This is because the LD side surface is a cleaved surface, and the accuracy is on the order of several tens of μm, and it cannot be mounted in accordance with this. Therefore, before mounting, the distance from the light emitting point of each LD to the side surface of the LD is measured. By observing the epitaxial surface, the position of the LD emission point can be measured as a relative distance from the side surface without causing light emission. Corresponding to this distance, the alignment mark 9 is formed at a desired distance.
[0046]
<Manufacturing method>
Here, a method for manufacturing the composite optical device of the above embodiment will be briefly described.
A quartz substrate is used as the optical member 2 for forming the microlenses 1 and 1 '. Since both surfaces of this substrate are finished by polishing, the surface roughness is several nm. Microlenses 1 and 1 'are formed on the surface using a gray scale mask. Details of the manufacturing method are described in Patent Document 8 and Patent Document 9.
[0047]
Thus, as shown in FIG. 1, the cross section of the produced lens is designed such that the apex of the lens is lower than the quartz substrate surface, that is, the first surface. An antireflection film is applied to the lens surface. The distance from the first surface to the position of the optical element, in this case, for example, the apex of the microlens, can be accurately formed by controlling the etching. Therefore, the distance between the light emitting element and the optical element can also be accurately supported with respect to a desired constant distance. This is because the first surface of the optical member 2 to be tightly bonded to the light emitting element and the optical element are manufactured as a unit.
[0048]
The quartz substrate on which this lens is formed is cut out by dicing to constitute the optical member 2. The shape was about 1 mm square. After the optical member 2 is diced, the surface to be polished is polished and finished with an accuracy of the order of several μm. The optical member 2 on which the microlens is formed is mounted on the submount 4 on which the LD 3 is mounted. The submount 4 is fixed to the side surface of the optical member 2 with a UV curable resin.
[0049]
For LD3, the one that has been externally processed by cleavage other than the upper and lower surfaces is used. The LD 3 is mounted on the submount 4 with the epitaxial surface facing down as a junction down. Mounting is performed so that the side surface of the submount 4 and the light emitting end surface formed by one cleavage surface of the LD 3 are substantially the same surface. This work can be mounted with high accuracy by observing with a microscope using a die bonder. In a microscope, this accuracy can be achieved by observing the side surface of the submount 4 and the emission end surface at the same time. The submount 4 mounted in this way and the emission end face of the LD 3 can be matched with an error of the order of several hundred nm. A detailed mounting method and the like are described in Patent Document 10 and the like.
[0050]
Next, the submount 4 is rotated 90 degrees so that the emission end face of the LD 3 becomes horizontal. The optical member 2 is placed on this surface. At this time, the optical member 2 is supported at the tip of the suction pin of the die bonder, but follows the other surface, that is, the end surface of the submount 4 or the emitting end surface of the LD 3 to follow the direction. It moves so that the center of the micro lens comes to the light emitting point in a state following the contact direction.
[0051]
At this time, it is also possible to confirm that the LD emits light and the emitted light becomes parallel light by the microlens. The parallel movement of the optical member 2 in a state of following the emission end face of the submount 4 or the LD 3 is performed by moving the suction pin of the die bonder in the X-axis and Y-axis directions with a micrometer.
With the production method described above, the mounting method of the present invention can suppress the manufacturing tolerance shown in FIG.
[0052]
FIG. 3 is a diagram showing the external dimensions of each part shown in FIG. Each manufacturing tolerance is indicated by ±. In addition, the following numerical values can be realized as important tolerances affecting the quality of light.
Table 1
Angle of view ± 0.1 degrees
Eccentric 2 μm
LD-lens distance ± 0.1μm
[0053]
Embodiment 2
FIG. 4 is a diagram illustrating the configuration of the second embodiment.
In the present embodiment, the convex microlens 1 is changed to a concave microlens 1 ″. As shown in FIG. 4, only the lens on the LD3 side is concave and is filled with a resin having a high refractive index.
By making the lens surface concave, the incident angle is reduced and the light loss due to reflection is reduced. If a concave surface is used, the lens power becomes negative as it is, but by filling a resin having a refractive index higher than that of the optical member 2, the lens power is made positive so that a condensing system is obtained.
[0054]
A groove for injecting a UV curable resin is formed at the time of photolithography when manufacturing the microlens 1 ″. The groove should have a height of several tens of μm and a width of about several hundreds of μm. The UV curable resin flows in by capillary action by hanging the UV curable resin in the UV curable resin injection groove in a state where the optical member "is in contact with the submount 4. When the flow is finished, UV is irradiated and cured. At this time, in the UV curable resin injection groove, an injection port through which the UV curable resin flows, a flow path through which the resin flows, and a barrier that does not flow into the microlens 1 ″ are formed.
Even if the microlens 1 ″ is concave, it can be made an anamorphic surface and the cross section can be made non-circular as in the case of the convex surface.
[0055]
<Manufacturing method>
Although it is difficult to make a concave lens by the ordinary reflow microlens 1 ″ manufacturing method, it can be realized by using the gray scale mask described above. A UV curable resin is sealed in the concave portion. Its refractive index is larger than quartz by about 1.6.By making the refractive index high, this lens works so that the divergence angle of the light beam from the LD 3 becomes small, that is, the same effect as a convex lens can be obtained. Epoxy, vinyl, acrylic, etc. can be used to achieve a high refractive index, this time using epoxy and increasing the hardness.If the resin has a high hardness, polishing with a quartz substrate is possible. It is also possible to make the quartz substrate and the resin surface coincide with each other.
[0056]
This time, in order to reduce the manufacturing cost of polishing, a method without polishing was adopted. In this method, the optical member 2 is brought into contact with the emission end face of the LD 3 and a resin is poured and cured in this state. If an injection groove into which the resin can be injected is formed in the concave portion, it can be injected in a contact state using the capillary phenomenon. The UV curable resin is also injected into the UV curable resin injection groove formed at the joint with the stem 4, and alignment is performed in this state. The alignment is the same as in the first embodiment. In this state, UV irradiation is also performed on the joint where the optical member 2 and the stem 4 are bonded to each other and fixed. The mounting accuracy can be increased as in the first embodiment.
[0057]
Embodiment 3
FIG. 5 is a diagram showing the configuration of the third embodiment.
The present embodiment is substantially the same as the first embodiment, but the shape of the stem 6 is different. That is, the optical member 2 is not supported by the stem 6 but supported only by the first surface. For this reason, the stem shape becomes simple, it is easy to process such as polishing, the surface roughness is reduced, and the mounting accuracy is increased. There is no need to increase the accuracy of the dicing surface of the optical member 2 by polishing or the like, and only a simple dicing process is required. In order to reinforce the fixing strength of the optical member 2 to the stem 6, the UV curable resin injection groove is made large. The manufacturing method and others are the same as in the first embodiment.
[0058]
Embodiment 4
FIG. 6 is a diagram showing Embodiment 4 in which the present invention is applied to an optical fiber. In this case, the end surface of the optical fiber 3 'corresponds to the plane of the light emitting element. The material of the optical member 2 can be changed according to the wavelength to be transmitted. When a long wavelength light source is used, a Si substrate can be used. In this case, an infrared microscope is used as an alignment method. For the stem 6, a crystal such as Si is used, and anisotropic etching of a semiconductor process is used to form a V groove. The V-groove can be formed with high accuracy by using a semiconductor process, and an optical fiber is mounted in the V-groove with high accuracy.
[0059]
The side surface of the stem 6 is aligned with the crystal direction of the crystal constituting the stem 6. This is the cleaving direction and can be easily manufactured. Moreover, the side surface of the stem 6 also has very high flatness by this processing method. By making the end face of the fiber coincide with this surface and bringing the first surface of the optical member 2 into contact with each other, high-precision mounting can be easily performed. Further, when the surface property of the fiber is deteriorated, a resin having a refractive index substantially similar to that of the fiber is poured between the microlens 1 and the fiber. Thereby, scattering of light on the fiber surface is eliminated, and high coupling efficiency can be obtained. The alignment mark 9 at the time of mounting is aligned using the outer shape of the V groove formed with high accuracy as a target mark.
[0060]
Embodiment 5
  FIG. 7 is a diagram showing the configuration of the fifth embodiment. Sign21, 21'Indicates an inclined surface forming one surface of the optical wedge.
  The divergence angle of LD differs greatly between the vertical direction and the horizontal direction. For this reason, the profile of light emitted therefrom is a vertically long ellipse. The object of the present embodiment is to shape the light emitted from the LD to make a perfect circle. The optical surface of the optical element is simply an inclined surface.21As an inclined surface on the exit surface side21In combination with ′, it plays the role of an optical wedge, and the light divergence angle is changed only in one direction. This direction is called the action direction.
[0061]
  Inclined surface of this embodiment21Is designed to reduce the vertical divergence angle. Inclined surface21Was calculated from the divergence angle of the light emitted from the LD3, and the light profile was designed to be a perfect circle. In addition, inclined surface21'May be the optical surface itself of the second surface of the optical member 2. The creation method is almost the same as in the first to fourth embodiments.
[0062]
We would like to design the chief ray of emitted light so that the traveling direction of the chief ray is perpendicular to LD3. However, when the chief ray exits LD3, it enters the optical wedge even if it is perpendicular to the exit end face of LD3. Then the direction will be changed. However, when the exit surface of the optical wedge is parallel to the entrance surface, the direction of the principal ray returns to the original and becomes perpendicular to the exit end surface of the LD 3. However, if the entrance surface and the exit surface are parallel, a triangular prism cannot be formed on these two surfaces, and the divergence angle of the light beam cannot be corrected. Therefore, in this method, the direction of the chief ray cannot be perpendicular to the exit end face of the LD 3 after exiting the composite optical device.
[0063]
FIG. 8 is a diagram for explaining how the divergence angle changes due to the action of the optical wedge. 8A is a diagram for explaining the maximum deflection angle, FIG. 8B is a diagram for explaining how the divergence angle is enlarged, and FIG. 8C is a diagram for explaining how the divergence angle is reduced.
The optical wedge is the same kind as a so-called triangular prism, and the divergence angle can be enlarged or reduced depending on the way the light beam is incident. As shown in FIG. 6A, there is a triangular prism having a maximum deflection angle θM. When the incident angle of the light beam with respect to the incident surface is equal to the outgoing angle with respect to the output surface, the angle formed by the incident light beam and the outgoing light beam, that is, the deflection angle is maximized. The declination angles, for example, θ1 and θ2, of light rays incident at other angles become smaller as the incident angle becomes farther from the maximum declination angle. In the figure, θM> θ1 and θM> θ2.
[0064]
Accordingly, when the incident angles of all the light beams are larger than the maximum deflection angle of incident angle θM, the light beam divergence angle is expanded. This is shown in FIG. In the figure, if the divergence angle of the incident light beam is ΘI and the divergence angle of the outgoing light beam is ΘO, then ΘO> ΘI. Conversely, when the incident angles of all the light beams are smaller than the angle θM, the divergence angle of the light beams is reduced. This is shown in FIG. In the figure, ΘO <ΘI. When the incident angle of a light beam in the middle of the light beam coincides with the maximum deviation angle θM, the divergence angle increases on the one side and the divergence angle decreases on the other side, so that the intensity distribution of the light beam is biased.
[0065]
  The optical wedge shown in this embodiment is an inclined surface formed on the first surface of the optical member 2.21And the inclined surface formed on the second surface21It plays the role of a triangular prism on the two sides. The inclined surface of the second surface21If 'is omitted, the inclined surface of the second surface21The optical surface of the second surface itself plays the role instead of '.
[0066]
Using the above properties, the optical wedge can be configured in two ways. That is, a configuration in which the divergence angle on the long axis side is reduced and a divergence angle on the short axis side is increased with respect to the elliptical cross section of the light beam. In the fifth embodiment, an example in which the long axis side divergence angle is reduced is shown. However, when it is desired to shape the diameter of the light beam as large as possible, the short axis side divergence angle may be increased.
[0067]
<Production method>
  Inclined surface21, 21A quartz substrate is used for the optical member '. Since this surface is finished by polishing, the surface roughness is several nm. Inclined surface on this surface21, 21'Is produced with a gray scale mask. As a result, the inclined surface produced21, 21The cross section of ′ is shown in FIG. Inclined surface21, 21An antireflection film is applied to the surface of '. This inclined surface21, 21The quartz substrate on which 'is formed is cut out by dicing to form the optical member 2. The shape was about 1 mm square. The optical member 2 is mounted on the submount 4 on which the LD 3 is mounted. The submount 4 is fixed to the LD3 contact surface and the first surface of the optical member with a UV curable resin.
[0068]
As the LD3, an outer shape processed by cleavage is used. The LD 3 is mounted on the submount 4 with the epitaxial surface facing down as a junction down. The side surface of the submount 4 and the emission end surface of the LD 3 are mounted so as to be substantially the same plane and parallel. This work can be mounted with high accuracy by observing with a microscope using a die bonder. In a microscope, this accuracy can be achieved by observing the side surface of the submount 4 and the emission end surface at the same time. The submount 4 mounted in this way and the emission end face of the LD 3 coincide with each other on the order of several hundred nm.
[0069]
Next, the submount 4 is rotated 90 degrees so that the emission end face of the LD 3 becomes horizontal. The optical member 2 having the previously inclined surface is placed on this surface. At this time, the optical member 2 is supported at the tip of the suction pin of the die bonder, but is adapted to follow the direction by coming into contact with the mating surface. This time, passive alignment was performed by using the method described above. The parallel movement of the optical member 2 in a state of following the submount 4 or the emission end face of the LD is performed by moving the suction pin of the die bonder in the X-axis and Y-axis directions with a micrometer.
[0070]
Embodiment 6
  FIG. 9 is a diagram showing the configuration of the sixth embodiment.
  Sign11, 11'Represents an elliptical diffraction grating.
  In this embodiment, an elliptical diffraction grating is used as a method for shaping the light profile.11, 11'Was used. Elliptical diffraction grating11, 11The light profile can be controlled by forming a wavelength level grating as a concentric elliptical groove on the optical member.
[0071]
  Elliptical diffraction grating11Is formed in a portion separated from the LD 3 by several tens of μm toward the optical member side. Elliptical diffraction grating11, 11'Is designed so that the light emitted from the LD becomes a perfect circle and becomes parallel light. Elliptical diffraction grating11, 11It is desired that the distance between ′ and the exit end face of the LD be a design value with high accuracy. In the present embodiment, high accuracy can be obtained by controlling the distance by dry etching.
[0072]
<Production method>
  Elliptical diffraction grating11, 11The optical member 'uses a quartz wafer. Since this surface is finished by polishing, the roughness of the surface is several nm. Elliptical diffraction grating11, 11'Is produced with a gray scale mask, and an antireflection film is applied to the surface of the diffraction grating. Oval diffraction grating produced by this11, 11The cross section of ′ was configured as shown in FIG. The quartz substrate on which the diffraction grating surface is formed is cut out by dicing to obtain an optical member 2. The shape was about 1 mm square. The optical member 2 is mounted on the submount 4 on which the LD 3 is mounted. The submount 4 is fixed to the LD3 contact surface and the side surface of the optical member 2 with a UV curable resin.
[0073]
As the LD3, an outer shape processed by cleavage is used. The LD 3 is mounted on the submount 4 with the epitaxial surface facing down as a junction down. The side surface of the submount 4 and the emission end surface of the LD 3 are mounted so as to be substantially the same plane and parallel. This work can be mounted with high accuracy by observing with a microscope using a die bonder. In a microscope, this accuracy can be achieved by observing the side surface of the submount 4 and the emission end surface at the same time. The submount 4 mounted in this way and the emission end face of the LD 3 coincide with each other on the order of several hundred nm.
[0074]
Next, the submount 4 is rotated 90 degrees so that the emission end face of the LD 3 becomes horizontal. The optical member 2 is placed on this surface. At this time, the optical member 2 is supported at the tip of the suction pin of the die bonder, but follows the direction by contacting the mating surface. This time, passive alignment was performed by using the method described above. The parallel movement of the optical member 2 in a state of following the emission end face of the submount 4 or the LD 3 is performed by moving the suction pin of the die bonder in the X-axis and Y-axis directions with a micrometer.
[0075]
Embodiment 7
FIG. 10 is a diagram showing the configuration of the seventh embodiment. FIG. 10a is a side view. FIG. 10b is a plan view, but the portions other than those necessary for the explanation are omitted.
Reference numerals 31 and 31 ′ denote cylindrical lenses.
In the present embodiment, the cylindrical lenses 31 and 31 'are used as a method for shaping the light profile. The cylindrical lenses 31 and 31 'have a parallel shape in the long side direction, and the mounting accuracy obtained in that direction is dramatically increased. Therefore, the cost related to mounting in that direction is reduced.
[0076]
The cylindrical lens does not have optical power in the long side direction, but has optical power only in one direction orthogonal thereto. A direction having optical power is sometimes referred to as an action direction. By converging the elliptical major axis direction of the light profile with the larger divergence angle, that is, the light beam with the smaller divergence angle direction, that is, matching the divergence angle with the minor axis direction, The profile of light emitted from the LD 3 can be designed to be elliptical to circular.
[0077]
As shown in the figure, the direction of action of the cylindrical lens 31 is matched with the direction of the larger divergence angle so as to converge the light beam, and the direction of action of the cylindrical lens 31 'is matched with the direction of the smaller divergence angle to converge the light beam. If the optical power of the cylindrical lens 31 is set larger than that of the cylindrical lens 31 ′, the design for shaping the light beam profile into a circle becomes relatively easy.
The distance between the cylindrical lens 31 and the exit end face of the LD 3 is desired to be mounted with high accuracy and a design value. In the present embodiment, high accuracy can be obtained by controlling the distance by dry etching.
[0078]
<Production method>
The optical members of the cylindrical lenses 31, 31 'use a quartz wafer. Since this surface is finished by polishing, the roughness of the surface is several nm. Cylindrical lenses 31, 31 'are formed on the surface using a gray scale mask.
[0079]
As a result, the cross-sections of the fabricated cylindrical lenses 31 and 31 'are as shown in FIG. 10, and an antireflection film is applied to the lens surface. The quartz substrate on which the cylindrical lenses 31 and 31 ′ are formed is cut out by dicing to form the optical member 2. The shape was about 1 mm square. The apex of the cylindrical lens 31 is formed lower than the first surface of the optical member 2. The optical member 2 is mounted on the submount 4 on which the LD 3 is mounted. The submount 4 is fixed to the contact surface of the LD 3 and the side surface of the optical member 2 with a UV curable resin.
[0080]
As the LD3, an outer shape processed by cleavage is used. The LD 3 is mounted on the submount 4 with the epitaxial surface facing down as a junction down. The side surface of the submount 4 and the emission end surface of the LD 3 are mounted so as to be substantially the same plane and parallel. This work can be mounted with high accuracy by observing with a microscope using a die bonder. In a microscope, this accuracy can be achieved by observing the side surface of the submount 4 and the emission end surface at the same time. The submount 4 mounted in this way and the emission end face of the LD 3 coincide with each other on the order of several hundred nm.
[0081]
Next, the submount is rotated 90 degrees so that the emission end face of the LD 3 is horizontal. The optical member 2 is placed on this surface. At this time, the optical member 2 is supported at the tip of the suction pin of the die bonder, but follows the direction by contacting the other surface. This time, passive alignment was performed by using the method described above. The parallel movement of the optical member 2 in a state of following the emission end face of the submount 4 or the LD 3 is performed by moving the suction pin of the die bonder in the X-axis and Y-axis directions with a micrometer.
[0082]
The optical surface of the cylindrical lens 31 formed on the first surface can be formed into a concave cylindrical lens 31 ″ as in the case of the microlens 1. In that case, the direction of the smaller divergence angle of the light beam, That is, the elliptical minor axis direction of the light profile may be matched with the direction of operation of the cylindrical lens 31 ″.
By filling the concave portion with a transparent resin having a refractive index higher than that of the optical member 2, it is possible to prevent the power from becoming negative and to use the lens system as a positive power. .
Similarly, the cross section having the optical power of the optical surface of the cylindrical lens 31 formed on the first surface can be made a non-circular surface.
[0083]
【The invention's effect】
According to the first aspect of the present invention, it is not necessary to make the spacer and the lens separately as in the conventional method, and it is possible to provide the functions of the spacer and the lens only by scraping the optical member. As a result, low-cost manufacturing is possible.
[0084]
  According to the invention described in claim 2, in the composite optical device according to claim 1,, DepartureSince there are few elements interposed between the optical elements, the distance between them can be set with high accuracy.
[0085]
  Claim 3According to the invention described in claim 1,Or 2In the composite optical device described in 1), the first surface can be easily polished because there is no convex portion on the first surface.
  Claim 4According to the invention described in claim 1,3In the composite optical device according to any one of the above, the light source can be made very small.
[0086]
  Claim 5According to the invention described in claim 1,4In the composite optical device according to any one of the above, since the optical elements are formed on the two surfaces, it is relatively easy to obtain the desired optical performance.
  According to the invention described in claim 6,5In the composite optical device described in any one of the above, the profile of the light beam can be shaped with high accuracy.
[0087]
  Claim 7According to the invention described inClaim 6In the composite optical device described in 1), the profile of the light beam can be shaped even with one optical surface.
  Claim 8According to the invention described in claim1 to 5In the composite optical device according to any one of the above, the profile of the light beam can be shaped with optical power in only one direction.
[0088]
  Claim 9According to the invention described inClaim 8In the composite optical device described in 1), the design for shaping the light beam profile into a circular shape becomes easy.
  Claim 10According to the invention described in claim6 to 9In the composite optical device according to any one of the above, since there is no portion protruding from the first surface of the optical member, contact with the mating surface can be performed with high accuracy.
[0089]
  Claim 11According to the invention described in claim6 to 8In the composite optical device according to any one of the above, the degree of freedom in design is increased by adopting a concave surface in the continuous drawing.
  Claim 12According to the invention described in claim6 to 11In the composite optical device according to any one of the above, various aberrations inherent to the lens system are removed, and a high-quality light beam can be obtained.
[0090]
  Claim 13According to the invention described in claim1 to 5In the composite optical device according to any one of the above, the profile of the light beam can be shaped by a simple plane.
  Claim 14According to the invention described inClaim 13In the composite optical device described in (1), the divergence angle of the outgoing light beam is larger than the divergence angle of the incident light beam.
[0091]
  Claim 15According to the invention described inClaim 14In the composite optical device described in 1), the smaller divergence angle of the semiconductor laser can be increased to match the larger divergence angle.
  Claim 16According to the invention described in item 14, in the compound optical device according to claim 14, the divergence angle of the outgoing light beam is smaller than the divergence angle of the incident light beam.
[0092]
  Claim 17According to the invention described inClaim 16In the composite optical device described in 1), the larger divergence angle of the semiconductor laser can be reduced to match the smaller divergence angle.
  Claim 18According to the invention described in claim1 to 5In the composite optical device according to any one of the above, the profile of the light beam can be shaped by a flat optical element perpendicular to the principal ray of the incident light beam.
[0093]
  Claim 19According to the invention described in claim1 to 18In the composite optical device according to any one of the above, the optical performance can be adjusted.
  Claim 20According to the invention described inClaim 19In the composite optical device described in 1), it is possible to prevent negative power from being generated by the concave surface. .
[0094]
  Claim 21According to the invention described inClaim 19In the composite optical device described in 1), when the exit end face of the optical fiber is used as the light emitting element, the roughness of the exit end face can be prevented from scattering light.
  Claim 22According to the invention described in claim1 to 21In the composite optical device according to any one of the above, the distance between the light emitting element and the optical element is not changed by the presence of the adhesive.
[0095]
  Claim 23According to the invention described in claim1 to 22In the composite optical device according to any one of the above, the alignment between the LD and the optical member becomes very simple.
  Claim 24According to the invention described inClaim 23A manufacturing method for manufacturing the composite optical device according to claim 1, wherein an emission end of the light emitting element is formed in the presence of the alignment mark.Face andThe first surface of the optical member can be abutted and joined.
[Brief description of the drawings]
FIG. 1 is a side view showing a configuration of a first embodiment of the present invention.
FIG. 2 is a front view showing the configuration of Embodiment 1 of the present invention.
FIG. 3 is a diagram showing the external dimensions of each part shown in FIG. 1;
FIG. 4 is a diagram illustrating a configuration of a second embodiment of the present invention.
FIG. 5 is a diagram showing a configuration of a third exemplary embodiment of the present invention.
FIG. 6 is a diagram showing a fourth embodiment in which the present invention is applied to an optical fiber.
FIG. 7 is a diagram showing a configuration of a fifth exemplary embodiment of the present invention.
FIG. 8 is a diagram for explaining how the divergence angle changes due to the action of the optical wedge.
FIG. 9 is a diagram illustrating a configuration of a sixth embodiment of the present invention.
FIG. 10 is a diagram illustrating a configuration of a seventh embodiment of the present invention.
FIG. 11 is a diagram for explaining a conventional form of mounting of an LD and a microlens.
FIG. 12 is a diagram for explaining a difference in incident angle with respect to a tangent line between a convex surface and a concave surface.
[Explanation of symbols]
  1 Microlens
  2 Optical members
  3 Semiconductor laser (LD)
  4 Submount
  5 UV curing resin injection groove
  6 stem
  7 UV curable resin
  8 LD epitaxial surface
  9 Alignment mark
11Elliptical diffraction grating
21Inclined surface
31 Cylindrical lens

Claims (24)

In a composite optical device in which a light emitting element and an optical member including an optical element are integrated, the optical member has a first surface that is a polished surface, and a second surface that faces the first surface, The optical element is obtained by processing a part of the first surface, and the first surface of the optical member is in contact with an emission end surface of the light emitting element. The composite optical apparatus according to claim 1, wherein the optical member has a function of supporting a distance between the light emitting element and the optical element at a constant level . 3. The composite optical device according to claim 1, wherein a concave portion is formed on a first surface of the optical member , and the optical element is formed on a bottom portion of the concave portion . 4. The composite optical device according to claim 1, wherein the light emitting element is a semiconductor laser . 5. 5. The composite optical device according to claim 1, wherein an optical element is also formed on the second surface of the optical member . 6. 6. The composite optical apparatus according to claim 1, wherein the optical element is a microlens . 7. The composite optical device according to claim 6 , wherein the optical surface of the microlens is an anamorphic surface . 7. The composite optical apparatus according to claim 1 , wherein the optical element is a cylindrical lens . 9. The compound optical device according to claim 8 , wherein the cylindrical lens has an operating direction aligned with an elliptical major axis direction of a cross section of the light beam on the first surface of the optical member, and a cross section of the light beam on the second surface. A compound optical device characterized in that the direction of action is aligned with the minor axis direction of the ellipse . 10. The composite optical device according to claim 6 , wherein a height of a vertex of the optical element on the first surface is lower than that of the first surface of the optical member. . 9. The composite optical apparatus according to claim 6 , wherein a lens surface of the optical element on the first surface is a concave surface . 12. The composite optical apparatus according to claim 6 , wherein a cross section having an optical power of the optical surface of the optical element is a non-circular surface . 7. The composite optical apparatus according to claim 1 , wherein the optical element is an optical wedge . 14. The composite optical device according to claim 13 , wherein incident angles of all light beams incident on the first surface correspond to a maximum deflection angle of an optical wedge formed by the optical surfaces of the first surface and the second surface. The optical surface is formed so as to be larger than the angle of the composite optical device. 15. The composite optical device according to claim 14, wherein an action direction of the optical wedge is aligned with a direction having a smaller divergence angle among light beams of light emitted from the semiconductor laser . 14. The composite optical device according to claim 13 , wherein incident angles of all light beams incident on the first surface correspond to a maximum deflection angle of an optical wedge formed by the optical surfaces of the first surface and the second surface. The optical surface is formed so as to be smaller than the angle of the composite optical device. 17. The composite optical device according to claim 16 , wherein an action direction of the optical wedge is aligned with a direction having a larger divergence angle among light beams of light emitted from the semiconductor laser . 7. The composite optical apparatus according to claim 1 , wherein the optical element is an elliptical diffraction grating . 19. The composite optical device according to claim 1 , wherein a space where the optical element does not exist is filled with a transparent member having a refractive index different from that of the optical member. Compound optical device. 20. The composite optical device according to claim 19 , wherein a refractive index of the transparent member is larger than a refractive index of the optical element . 20. The composite optical device according to claim 19 , wherein the light emitting element is an optical fiber end face, and the refractive index of the transparent member is approximately equal to the refractive index of the light emitting element . 23. The composite optical device according to claim 1 , wherein a groove is formed in the first surface of the optical member, and an adhesive is injected into the groove . 23. The composite optical device according to claim 1, wherein an alignment mark is formed on the optical member. 24. A manufacturing method for manufacturing a composite optical device according to claim 23 , wherein an alignment mark of the optical member is aligned with a mark on a plane of the light emitting element, an emission end face of the light emitting element, and a first of the optical member. A method of manufacturing a composite optical device, comprising: abutting and joining surfaces.

Images