JP2001350042A - Optical module and light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical module, which can exactly adjust the light quantity of the luminous fluxes to be case to a photoreceptor, etc., and can be made small-sized and a light source device. SOLUTION: This optical module has waveguide cores 25, 26 and 27, which guide the rays of the incident light emitted from light sources 21, 22 and 23 and made incident from incident surfaces 25a, 26a and 27a to exit surfaces 25b, 26b and 27b and incline the exit surfaces 25b, 26b and 27b, with respect to the progression direction of the rays of the guided light L and photodetectors 41, 42 and 43, which receive the rays of the reflected light L5 reflected by the exit surfaces 25b, 26b and 27b and detect the light quantity thereof. The outputs of the light sources 21, 22 and 23 are made variable, based on the light detected by the photodetectors 41, 42 and 43.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical module and a light source device for emitting light from a light source through a waveguide, and more particularly to an optical module and a light source device capable of adjusting the output of a light source by feedback.

[0002]

2. Description of the Related Art A laser printer or a copying machine scans a light beam emitted from a light source to write on a photosensitive member. In addition, high-speed scanning can be performed by using a plurality of light beams and condensing the light at different positions in the circumferential direction of the photoconductor. The light source is composed of a semiconductor laser as shown in FIG.

An active layer 1 sandwiched between a lower cladding layer 13 and an upper cladding layer 15 is provided on a substrate 12 of a semiconductor laser.
4 is formed, the lower surface of the substrate 12 and the upper cladding layer 15 are formed.
The electrodes 11 and 16 are arranged on the upper surface of the. Electrodes 11, 1
Light fluxes L1 and L2 are emitted from light emitting points 14a and 14b (14a not shown) formed on two surfaces of the active layer 14 by applying a voltage between the six.

The light beam L1 from the light emitting point 14a is guided to a plurality of optical fibers and waveguides (not shown) and is used for writing on a photosensitive member. The light beam L2 emitted from the light emitting point 14b is applied to a light receiving element (not shown). The light receiving element detects the amount of received light, and based on the detection result, the control unit (not shown) controls the APC (Automatic Power Control).
l) Adjustments are made.

As a result, the drive current of the semiconductor laser is changed, and the fluctuation of the light emission intensity caused by the change of the ambient temperature of the semiconductor laser is canceled, so that the light quantity of the light beam emitted from the light source 17 is made constant. I have.

However, the light beam L1 emitted from the light source 17
When the optical characteristics of an optical system such as a waveguide or an optical fiber through which the light beam changes due to the ambient temperature or the like, the APC adjustment is performed by the light beam L2 that does not pass through the optical system. Light intensity is not kept constant.

Therefore, for example, when a light source is coupled to a waveguide, when the ambient temperature changes from 20 ° C. to 80 ° C.,
Due to the decrease in the coupling efficiency, the light quantity of the light beam after passing through the waveguide fluctuates by about 10%. In particular, when an image is formed by a plurality of light beams, if the difference in the light amounts of the light beams is not maintained at 5% or less, a bad image such as stripes occurs in the formed image, and thus there is a problem that a good image cannot be obtained. .

Therefore, as shown in FIG. 11, there has been proposed a light source device capable of performing APC adjustment after a light beam emitted from a light source 40 passes through an optical system. According to the figure, a light beam L1 emitted from a light source 40 composed of a semiconductor laser or the like enters the optical module 30.

In the optical module 30, a lower cladding layer 28 is formed on a substrate 24, and a plurality of waveguide cores 20 are formed on the lower cladding layer 28. The upper part of the waveguide core 20 is covered with an upper cladding layer 29. The upper cladding layer 29 and the lower cladding layer 28 have a lower refractive index than the waveguide core 20, and confine a light beam incident from the incident surface 20a and guide it to the emission surface 20b.

On the substrate 24, a light source 40 similar to that of FIG. 10 is integrally formed. A beam splitter 31 is disposed behind the emission surface 20b of the waveguide core 20. The light beam emitted from the light source 40 toward the incident surface 20a is guided through the waveguide core 20 and is emitted from the emission surface 20b. Then, the light passes through the beam splitter 31 and is used for writing on the photoconductor.

A part of the light beam exiting the exit surface 20b is reflected by the beam splitter 31 and enters a light receiving element 32 composed of a photodiode. The light receiving element 32 detects the amount of light received, and performs APC adjustment of the light source 40 by a control unit (not shown) based on the detection result. As a result, the drive current of the semiconductor laser is varied, and the fluctuation of the light amount caused by the change of the ambient temperature of the semiconductor laser and the optical system is canceled, so that the light amount of the light beam L3 after passing through the optical system is made constant. As a result, stripes and the like generated in the formed image can be prevented.

[0012]

However, according to the above-described conventional light source device 10, the beam splitter 31 and the light receiving element 32 are required for detecting the light amount of the light beam L3 emitted from the light source 40. Had the problem of becoming large. In addition, there is another problem that each component needs to be aligned and the assembly process is complicated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical module and a light source device capable of accurately adjusting the amount of a light beam irradiated to a photoreceptor and the like, and being compact and easy to manufacture.

[0014]

According to an aspect of the present invention, there is provided an optical module for guiding an incident light incident from an incident surface to an exit surface, and a light flux of the guided light beam. It is characterized by comprising a waveguide having the emission surface inclined with respect to the traveling direction, and a light receiving element for receiving a light beam reflected on the emission surface and detecting the amount of light.

According to this configuration, the light beam incident from the entrance surface is guided to the exit surface by the waveguide and exits. In addition, a part of the light beam is reflected on the exit surface of the waveguide, and the amount of reflected light is detected by the light receiving element. Then, by adjusting the output of the light source based on the detected light amount, deterioration of the coupling efficiency of the light source, the optical fiber, and the like coupled to the incident surface can be canceled.

According to a second aspect of the present invention, in the optical module according to the first aspect, the light receiving element is arranged parallel to a surface on which the waveguide is formed.

According to a third aspect of the present invention, in the optical module according to the second aspect, the waveguide is made of a film-shaped resin.

According to a fourth aspect of the present invention, in the optical module according to the first aspect, the waveguide is formed on a transparent substrate, and the light receiving element is provided on a back surface of the substrate. It is characterized by. According to this configuration, the light beam reflected on the emission surface through the waveguide is transmitted through the substrate and received by the light receiving element.

According to a fifth aspect of the present invention, in the optical module according to the first aspect, the light receiving element is arranged perpendicular to a surface on which the waveguide is formed.

According to a sixth aspect of the present invention, there is provided a light source device according to any one of the first to fifth aspects, a light source for irradiating the incident surface with a light beam, and detection of the light receiving element. A control unit for controlling the output of the light source based on the result.

According to this structure, the light beam emitted from the light source enters from the incident surface, is guided to the emission surface by the waveguide, and is emitted as the secondary light source. At this time, a part of the light beam is reflected by the light exit surface, is received by the light receiving element, and the amount of light is detected. The output of the light source is adjusted by the control unit so that the light amount of the secondary light source becomes constant based on the detected light amount.
Furthermore, when this configuration is applied to a light beam writing device using an optical module having a plurality of waveguides, the amount of light emitted from each waveguide can be controlled individually, so that stable writing can be realized.

According to a seventh aspect of the present invention, in the light source device according to the sixth aspect, the optical module and the light source are provided integrally.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. For convenience of description, the same parts as those in FIGS. 10 and 11 of the conventional example are denoted by the same reference numerals.
FIG. 1 is a schematic perspective view showing a light beam writing device provided with the light source device of the first embodiment. The light beam writing device 1 is mounted on a laser printer, a digital copier, or the like, and can form an image.

The light source device 10 has a built-in light source.
A plurality of light beams having different light condensing positions are emitted. Light source device 1
The luminous flux emitted from 0 illuminates the polygon mirror 3 after being collimated by the collimator lens 2. The light beam reflected by the polygon mirror 3 is scanned as the polygon mirror 3 rotates. After the scanning speed is made constant by the scanning lens 4, a desired position on the photoconductor is exposed by focusing on a photoconductor (not shown), and writing is performed.

The light beam reflected by the polygon mirror 3 irradiates the reflection mirror 5 at the leading position of each scanning line. The light beam reflected by the reflecting mirror 5 is captured by the light receiving sensor 6 so that the synchronization of the plurality of light beams can be detected.

The light source device 10 has an optical module 30 integrally formed with the light sources 21, 22, and 23 as shown in the plan views and side sectional views of FIGS. 2 (a) and 2 (b). In the optical module 30, a lower cladding layer 28 is formed on a substrate 24, and waveguide cores 25, 26,
27 are formed. The upper portions of the waveguide cores 25, 26, 27 are covered with an upper cladding layer 29.

Upper cladding layer 29 and lower cladding layer 2
8 has a lower refractive index than the waveguide cores 25, 26, 27. Thereby, the incident surfaces 25a, 26a, 27a
Out of the exit surfaces 25b, 26b,
The light is guided to 27b.

The exit surfaces 25b, 26b, 27b are, together with the upper cladding layer 29 and the lower cladding layer 28, at an inclination angle α with respect to a plane perpendicular to the traveling direction of the guided light L3 passing through the waveguide cores 25, 26, 27. It is formed inclined.
Therefore, the outgoing light L4 emitted from the outgoing surfaces 25b, 26b, 27b is refracted at the refraction angle β and emitted, and the guided light L3
Are reflected light L5 reflected by the emission surfaces 25b, 26b, 27b.

Light receiving elements 41, 42, and 43 formed of photodiodes are formed below the lower cladding layer 28 so as to receive the reflected light L5, perform photoelectric conversion, and detect the amount of received light. .

Such an optical module 30 can be manufactured by the method shown in FIG. First, as shown in FIG. 3A, on a substrate 24 made of silicon or the like, sputtering and etching of an electrode material, a P-type semiconductor and an N-type semiconductor are continuously performed to form light receiving elements 41, 4 having a predetermined shape.
2, 43 are formed.

Next, as shown in FIG. 3B, quartz is deposited to a thickness of 7 μm while doping fluorine by CVD to form a lower cladding layer 28. Lower cladding layer 28
On top of this, quartz is doped by CVD without doping.
After depositing μm and patterning into a predetermined shape by a photolithography process, reactive ion etching is performed to form waveguide cores 25, 26, and 27. Then, 7 μm of quartz is deposited while doping with fluorine to form an upper cladding layer 29.

Next, as shown in FIG. 3 (c), the incident surfaces 25a, 26a, 27a of the waveguide cores 25, 26, 27 are formed on the substrate 24 by dicing together with the lower cladding layer 28 and the upper cladding layer 29. And cut vertically.
Similarly, the emission surfaces 25b, 26b, and 27b are cut obliquely with respect to the substrate 24 by dicing together with the lower cladding layer 28 and the upper cladding layer 29.

Next, as shown in FIG.
Light sources 21, 22, and 23 composed of semiconductor lasers are fixed on the substrate. Thereby, the optical module 30 in which the light sources 21, 22, 23 are integrated can be obtained. The optical module 30 of the present embodiment obtained by the above-described manufacturing method is as follows.

Material of substrate: Silicon Material of waveguide core: Quartz Effective refractive index Neff of waveguide core: 1.459 Relative refractive index difference between upper cladding layer, lower cladding layer and waveguide: 0.3% Waveguide Cross section of core: 5 μm × 5 μm Inclination angle α of exit surface of waveguide core: 10 °

As a result, the refraction angle β of the emitted light L4 is about 4.7 °, but if it is about this degree, there is no particular problem in designing the light beam writing device 1 and the like. Further, the waveguide core 25,
Since the total reflection angles of 26 and 27 are about 43 °, the output surface 25b,
The inclination angle α of 26b and 27b is preferably in the range of 4 ° to 30 °.

FIG. 4 is a block diagram showing the configuration of the light source device 10. The light source device 10 has a control unit 31 for controlling the outputs of the light sources 21, 22, and 23. Light sources 21, 22, 2
The light beams emitted from the light source 3 are guided by the waveguide cores 25, 26, 27.
And the outgoing light L4 at the outgoing surfaces 25b, 26b and 27b.
And reflected light L5. Then, the light receiving elements 41, 4
The light quantity of each reflected light L5 is detected by 2 and 43.

The result detected by the light receiving elements 41, 42, 43 is compared with the light amount data of the predetermined reflected light L 5 stored in the storage unit 34 by the comparing unit 32. Comparison section 3
If the light amount of the reflected light L5 is not within the predetermined range as a result of the comparison by 2, it is determined that the output light L4 is not at the predetermined light amount, and the driving current of the light sources 21, 22, and 23 is varied by the driving unit 33. Thus, the outputs of the light sources 21, 22, and 23 are varied.

When the amount of the reflected light L5 is within a predetermined range, the drive section 33 maintains the drive current of the light sources 21, 22, and 23. Thereby, the adjustment is performed so that the emission light L4 of a constant light amount is always emitted from the emission surfaces 25b, 26b, 27b of the waveguide cores 25, 26, 27.

According to the present embodiment, the waveguide cores 25, 2
The light-emitting surfaces 25b, 26b, 27b of
In the direction of travel. Then, since a part of the guided light L3 is reflected by the emission surfaces 25b, 26b, 27b and the output of the light sources 21, 22, 23 can be adjusted by the amount of the light, the beam splitter 31 as in the conventional example is required. Instead, the light receiving element can be formed integrally with the optical module 30. Therefore, the light source device 10 can be formed in a small size, and the light source device 10 can be easily manufactured without the necessity of positioning the light receiving element and the beam splitter as in the conventional example.

Next, FIG. 5 shows a light source device 1 according to the second embodiment.
FIG. 2 is a side sectional view showing an optical module 30 of No. 0; For convenience of explanation, the same parts as those in the first embodiment shown in FIG. 2 are denoted by the same reference numerals. The difference from the first embodiment is that the light receiving elements 41, 42, 43 are embedded in the substrate 24. Other configurations are the same as those of the first embodiment. A groove 24a is formed on the substrate 24 by etching or the like, and light receiving elements 41, 42, and 43 are formed in the groove 24a. With such a configuration, the same effect as in the first embodiment can be obtained.

FIG. 6 shows a light source device 1 according to the third embodiment.
FIG. 2 is a side sectional view showing an optical module 30 of No. 0; For convenience of explanation, the same parts as those in the first embodiment are denoted by the same reference numerals. The difference from the first embodiment is that the substrate 24 is formed of a transparent material such as quartz,
1, 42 and 43 are formed on the back surface 24 b of the substrate 24. Other configurations are the same as those of the first embodiment.

The guided light L3 guided through the waveguide cores 25, 26 and 27 is output from the output surfaces 25b, 26b and 27b.
And the reflected light L5, and the reflected light L5 is transmitted through the lower cladding layer 28 and the substrate 24 to receive the light receiving elements 41, 42, 4
3 is received. Thereby, the same effect as in the first embodiment can be obtained. Also, the light receiving elements 41, 4
2, 43 may be separately prepared and attached to the back surface 24b of the substrate 24.

Next, FIG. 7 shows a light source device 1 according to a fourth embodiment.
FIG. 2 is a side sectional view showing an optical module 30 of No. 0; For convenience of explanation, the same parts as those in the first embodiment are denoted by the same reference numerals. The difference from the first embodiment is that the waveguide core 2
The light-emitting elements 4, 26, 27 have the emission surfaces 25 b, 26 b, 27 b inclining in such a direction that the upper portions project toward the emission side.
1, 42 and 43 are formed on the upper surface of the upper cladding layer 28. Other configurations are the same as those of the first embodiment.

With this configuration, a part of the guided light L3 is reflected upward by the emission surfaces 25b, 26b, and 27b, and is received by the light receiving elements 41, 42, and 43.
Thereby, the same effect as in the first embodiment can be obtained. The light receiving elements 41, 42, and 43 may be separately formed and attached to the upper surface of the upper cladding layer 29.

In the third and fourth embodiments, the lower cladding layer 28, the waveguide cores 25, 26 and 27, and the upper cladding layer 29 are formed by a so-called polymer waveguide core made of a film-like resin. , May be attached on the substrate 24. Then, the light receiving elements 41, 42, and 43 are attached to the substrate 2
A similar optical module 30 can be obtained by attaching the optical module 30 to the back surface of the substrate 4 or the upper surface of the upper clad layer 29.

Next, FIG. 8 shows a light source device 1 according to a fifth embodiment.
FIG. 3 is a plan view showing an optical module 30 of No. 0; For convenience of explanation, the same parts as those in the first embodiment are denoted by the same reference numerals. The difference from the first embodiment is that the waveguide core 25 is formed to be curved in a plane parallel to the substrate 24, and the emission surface 25b of the waveguide core 25 is formed perpendicular to the substrate 24. . The light receiving element 41 is arranged perpendicular to the substrate 24. Other configurations are the same as those of the first embodiment.

With such a configuration, the exit surfaces 25b, 26b, and 27b can be inclined with respect to the traveling direction of the guided light L3, and the reflected light L5 reflected by the exit surfaces 25b, 26b, and 27b is directed laterally. Reflected, light receiving elements 41, 4
2, 43 receive light. Thereby, the same effect as in the first embodiment can be obtained. Light receiving elements 41, 4
2 and 43 may be separately prepared and attached to the side surface of the optical module 30.

Next, FIG. 9 shows a light source device 1 according to the sixth embodiment.
FIG. 3 is a plan view showing an optical module 30 of No. 0; For convenience of explanation, the same parts as those in the first embodiment are denoted by the same reference numerals. The difference from the first embodiment is that each waveguide core 25,
The point is that one light receiving element 44 is provided in place of the light receiving elements 41, 42 and 43 in order to detect the light amounts of the branched lights 26 and 27. Other configurations are the same as those of the first embodiment.

According to the present embodiment, each waveguide core 25,
When detecting the light amount of the reflected light L5 reflected by the emission surfaces 25b, 26b, 27b of the light sources 21, 22, 2,
By driving the light sources 3 separately, the light amount of each reflected light L5 can be detected by the light receiving element 44. The output of the light sources 21, 22, and 23 is adjusted by the control unit 31 (see FIG. 4), so that the light amount of the outgoing light L4 emitted from the optical module 30 can be kept constant.

In the first to sixth embodiments described above, the optical module 30 and the light sources 21, 22, and 23 are integrally formed, but these are formed separately, and the optical fiber and the prism are connected to the optical module. The light beam from the light source may be incident on the light source 30 by being coupled thereto. Further, each waveguide core 25, 2
Light sources 21, 22, and 23 are provided for each of the light sources 6 and 27.
From the two light sources and the respective incident surfaces 25a, 26a, 27
a. In this case, an adjusting means for adjusting the amount of light incident on the waveguide cores 25, 26, 27 is separately required.

[0051]

According to the present invention, by forming the exit surface of the waveguide so as to be inclined with respect to the traveling direction of the guided light, a part of the guided light is reflected by the exit surface and the light amount is reduced by the light receiving element. It can detect and adjust the output of the light source. Therefore, the light receiving element can be formed integrally with the optical module without requiring a beam splitter as in the conventional example.
Therefore, the light source device can be formed in a small size, and it is possible to easily manufacture the light source device without the necessity of positioning the light receiving element and the beam splitter as in the conventional example.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a light beam writing device including a light source device according to a first embodiment of the present invention.

FIG. 2 is a plan view and a side cross-sectional view illustrating the light source device according to the first embodiment of the present invention.

FIG. 3 is a side sectional view illustrating a method of manufacturing the light source device according to the first embodiment of the present invention.

FIG. 4 is a block diagram illustrating a configuration of the light source device according to the first embodiment of the present invention.

FIG. 5 is a side sectional view showing a light source device according to a second embodiment of the present invention.

FIG. 6 is a side sectional view showing a light source device according to a third embodiment of the present invention.

FIG. 7 is a side sectional view showing a light source device according to a fourth embodiment of the present invention.

FIG. 8 is a plan view showing a light source device according to a fifth embodiment of the present invention.

FIG. 9 is a plan view showing a light source device according to a sixth embodiment of the present invention.

FIG. 10 is a perspective view showing a conventional light source.

FIG. 11 is a plan view showing a conventional light source device.

[Explanation of symbols]

 Reference Signs List 1 light beam writing device 2 collimator lens 3 polygon mirror 4 scanning lens 5 reflection mirror 6 light receiving sensor 10 light source device 11, 16 electrode 12 substrate 13 lower cladding layer 14 active layer 15 upper cladding layer 21, 22, 23 light source 24 substrate 25 , 26, 27 Waveguide core 28 Lower cladding layer 29 Upper cladding layer 30 Optical module 31 Control unit 32 Comparison unit 33 Drive unit 34 Storage unit 41, 42, 43, 44 Light receiving element

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H04N 1/113 B41J 3/00 D 5C072 1/23 103 H04N 1/04 104A 5C074 (72) Inventor Naoki Nishida Osaka city center 2-13-3 Azuchicho, Ward F-term in Osaka International Building Minolta Co., Ltd. (reference) 2C362 AA43 AA45 AA47 AA53 AA54 AA59 AA61 AA63 DA06 2H037 BA02 BA11 CA34 DA03 2H045 AA01 BA22 BA32 CB42 DA02 2H047 KA03 KA05 PA07 PA04 PA28 QA02 QA05 RA04 TA01 TA43 5C051 AA02 CA07 DB02 DB22 DB24 DB25 DB30 DC04 DC05 DC07 DE30 FA01 5C072 AA03 BA04 CA06 CA14 DA02 DA04 DA07 DA21 HA02 HA06 HA08 HA13 HB02 HB04 XA01 XA05 5C074 AA05 BB03 GG03 BB03 BB03 BB03 BB03 GG03 BB03 GG03

Claims (7)

[Claims] 1. A waveguide in which incident light incident from an incident surface is guided to an exit surface, and a waveguide in which the exit surface is inclined with respect to a traveling direction of a guided light beam, and a light beam reflected by the exit surface is received. And a light receiving element for detecting the amount of light. 2. The optical module according to claim 1, wherein said light receiving element is arranged parallel to a surface on which said waveguide is formed. 3. The optical module according to claim 1, wherein the waveguide is formed on a transparent substrate, and the light receiving element is provided on a back surface of the substrate. 4. The optical module according to claim 2, wherein the waveguide is made of a film-like resin. 5. The optical module according to claim 1, wherein the light receiving element is arranged perpendicular to a surface on which the waveguide is formed. 6. An optical module according to claim 1, wherein the light source irradiates a light beam onto the incident surface.
A light source device comprising: a control unit that controls an output of the light source based on a detection result of the light receiving element. 7. The light source device according to claim 6, wherein the optical module and the light source are provided integrally.