CN114035268B - Optical cross waveguide unit - Google Patents

Abstract

The invention belongs to the field of integrated photonic devices, and particularly relates to an optical cross waveguide unit which comprises a flat optical waveguide and at least two strip optical waveguide groups, wherein each strip optical waveguide group comprises two strip optical waveguides which are respectively an input strip optical waveguide and an output strip optical waveguide; the planar optical waveguide comprises at least two total internal reflection mirror groups, the total internal reflection mirror groups are arranged in one-to-one correspondence with the strip optical waveguide groups, each total internal reflection mirror group comprises a plurality of total internal reflection mirrors, and each total internal reflection mirror group is used for guiding all optical waves input by the input strip optical waveguide in the corresponding strip optical waveguide group to the corresponding output strip optical waveguide; the output end of the input strip-shaped optical waveguide and the input end of the output strip-shaped optical waveguide extend into the lower part of the flat plate-shaped optical waveguide, and a gap is formed between the output end of the input strip-shaped optical waveguide and the flat plate-shaped optical waveguide, and the thickness of the gap is 0.01-0.2 μm. The structure greatly reduces the loss of light wave energy and ensures the low energy loss of the crossed waveguide.

Description

An optical cross waveguide unit

technical field

The invention belongs to the field of integrated photonic devices, in particular to an optical cross waveguide unit.

Background technique

As the most basic unit in an optical integrated circuit, an optical waveguide connects different optical devices and guides the propagation of optical signals. According to the different geometric shapes of the optical waveguide, the optical waveguide can be divided into a flat optical waveguide and a strip optical waveguide. When the light wave propagates in the strip optical waveguide, the propagation mode of the optical waveguide has a refractive index difference in the lateral and longitudinal directions of the waveguide. , the light wave propagates along the length direction of the strip-shaped optical waveguide in the core layer, while when the plate-shaped optical waveguide propagates the light wave, the light wave is only confined in the longitudinal direction when propagating in the core layer. In optical integrated circuits, various optical devices are usually integrated on a single-layer space. Most of the existing crossed waveguides are based on strip-shaped optical waveguides with rough sidewalls, and the energy loss of the light wave in the X direction is relatively large. Energy will be lost.

Therefore, the existing technology needs to be improved and developed.

SUMMARY OF THE INVENTION

The purpose of the present application is to provide an optical cross-wave guide unit, which aims to solve a large amount of light wave energy loss in the existing cross-wave transmission process, thereby ensuring low energy loss of the cross-wave guide.

In order to achieve the above object, the present invention adopts the following technical scheme: an optical cross-waveguide unit, comprising a flat-shaped optical waveguide and at least two strip-shaped optical waveguide groups, each of the strip-shaped optical waveguide groups includes two strip-shaped optical waveguides a waveguide, the two strip-shaped optical waveguides are respectively an input strip-shaped optical waveguide and an output strip-shaped optical waveguide;

The plate-shaped optical waveguide includes at least two total internal reflection mirror groups, and the total internal reflection mirror groups are arranged in a one-to-one correspondence with the strip-shaped optical waveguide groups, and each of the total internal reflection mirror groups includes a plurality of total internal reflection mirror groups. reflecting mirrors, each of the total internal reflection mirror groups is used to guide all the light waves input by the input strip-shaped optical waveguides in the corresponding strip-shaped optical waveguide group to the corresponding output strip-shaped optical waveguides;

The output end of the input strip-shaped optical waveguide and the input end of the output strip-shaped optical waveguide protrude below the plate-shaped optical waveguide and have a gap with the plate-shaped optical waveguide, and the thickness of the gap is 0.01μm -0.2μm.

The optical cross waveguide unit provided by the present application has a double-layer structure composed of at least two strip-shaped optical waveguide groups and a flat-shaped optical waveguide group, and there is a gap between the strip-shaped optical waveguide group and the flat-shaped optical waveguide group, and the thickness of the gap is 0.01 μm -0.2μm, high coupling efficiency can be achieved when the light wave is coupled from the strip-shaped optical waveguide group to the flat-shaped optical waveguide; when the light wave is input from the input strip-shaped optical waveguide, it is coupled to the flat-shaped optical waveguide at the output end of the input strip-shaped optical waveguide At this time, the total internal reflection mirror group guides all the input light waves to the corresponding output strip optical waveguides. Due to the function of the total internal reflection mirror group, the light waves do not touch the rough side walls when propagating in the flat optical waveguide, which greatly reduces the The loss of light wave energy is reduced, and the low energy loss of the cross waveguide is ensured, thereby improving the propagation efficiency and overall performance of the optical signal in the optical integrated chip.

Further, the plate-shaped optical waveguide includes four straight edges, the four straight edges are respectively a first straight edge, a second straight edge, a third straight edge and a fourth straight edge, the first straight line The edge is parallel to the edge of the third straight line, and the edge of the second straight line is parallel to the edge of the fourth straight line; wherein the two strip-shaped optical waveguides of one of the strip-shaped optical waveguide groups are respectively facing the first The straight edge and the third straight edge are disposed, and the two strip-shaped optical waveguides of the other strip-shaped optical waveguide group are respectively disposed opposite to the second straight edge and the fourth straight edge.

The flat-shaped optical waveguide of the present application is provided with four straight edges. The two strip-shaped optical waveguides face the second straight edge and the fourth straight-line edge respectively. Since the two strip-shaped optical waveguide groups are set apart, there will be no signal crosstalk like other strip-shaped optical waveguides directly intersecting. Cross-wave signals with low crosstalk.

Further, the strip-shaped optical waveguide includes an equal-width portion away from one end of the flat-shaped optical waveguide and a widened portion close to one end of the flat-shaped optical waveguide. Along the axial direction of the strip-shaped optical waveguide, the equal-width portion The width of the wide portion remains unchanged, and the width of the widened portion gradually increases from the end facing away from the plate-shaped optical waveguide to the end facing the plate-shaped optical waveguide.

In this application, the width of the equal-width part at the end of the strip-shaped optical waveguide away from the flat-shaped optical waveguide remains unchanged. When the Gaussian beam commonly used in single-mode fiber communication is used as the incident light wave, the equal-width part can be well matched with the optical mode field. Matching, set the widened part of the strip optical waveguide close to one end of the flat optical waveguide. The widened part gradually increases from the end facing away from the flat optical waveguide to the end pointing to the flat optical waveguide, in order to reduce the diffraction effect. This further reduces losses.

Further, the total internal reflection mirror is a curved mirror, and the curved mirror is a concave mirror.

In this application, the total internal reflection mirror is a curved mirror, and the curved mirror is a concave mirror. Because the concave mirror has a light-gathering effect, it can make parallel light rays converge at the focus, and can also reflect the light emitted from the focus into parallel light, further reducing the light wave loss of energy.

Further, the plate-shaped optical waveguide is rectangular, and the two total internal reflection mirror groups are arranged in the rectangle, and each of the total internal reflection mirror groups includes two total internal reflection mirrors, which are the first total internal reflection mirror respectively. an internal reflection mirror and a second total internal reflection mirror, the first total internal reflection mirror is used to reflect all the incident light waves of the corresponding input strip-shaped optical waveguide to the corresponding second total internal reflection mirror, the The second total internal reflection mirror is used for reflecting all the reflected light waves of the corresponding first total internal reflection mirror to the corresponding output strip light waveguide.

Further, the distance from the starting point of the input light wave of the flat optical waveguide to the corresponding reflection point of the first total internal reflection mirror is equal to the Rayleigh distance of the Gaussian light wave; the reflection point of the first total internal reflection mirror is The distance of the reflection point of the corresponding second total internal reflection mirror is equal to twice the Rayleigh distance of the Gaussian light wave.

Further, both the strip-shaped optical waveguide and the flat-shaped optical waveguide have an outer cladding, and the outer cladding is silicon dioxide.

Further, the thickness of the strip-shaped optical waveguide is 0.22 μm, the width of the equal-width portion is 0.45 μm, and the width of the end face of the widened portion close to one end of the flat-shaped optical waveguide is 1.5 μm.

Further, the length of the widened portion is 5 μm-7 μm.

，F为高 斯光波的瑞利距离。 Further, the reflection surface of the total internal reflection mirror is an arc surface, and the radius of the arc surface is

, F is the Rayleigh distance of the Gaussian light wave.

Beneficial effects, the optical cross waveguide unit of the present invention is provided with a double-layer structure composed of at least two strip-shaped optical waveguide groups and a flat-shaped optical waveguide. The flat-shaped optical waveguide includes at least two total internal reflection mirror groups, each of which is The optical waveguide group includes an input strip optical waveguide and an output strip optical waveguide, each total internal reflection mirror group includes a plurality of total internal reflection mirrors, and the output end of the input strip optical waveguide and the input of the output strip optical waveguide The end protrudes below the plate-shaped optical waveguide and has a gap between the plate-shaped optical waveguide and the plate-shaped optical waveguide, and the thickness of the gap is 0.01 μm-0.2 μm, so that the light wave coupling efficiency is high. When the light wave is input from the input end of the input strip-shaped optical waveguide, and coupled from the output end of the input strip-shaped light wave to the flat-shaped optical waveguide, all the light waves entering the flat-shaped optical waveguide are all reflected by the total internal reflection mirror group for multiple times. guide to the output strip light guide. Due to the function of the total internal reflection mirror, the light wave does not contact the rough side wall when propagating in the flat optical waveguide, which greatly reduces the loss of light wave energy and ensures the low energy loss of the cross waveguide; and there is no direct connection between the strip optical waveguide groups. Crosstalk can greatly reduce the crosstalk of the optical signal, thereby improving the propagation efficiency and overall performance of the optical signal in the optical integrated chip.

Description of drawings

FIG. 1 is a schematic structural diagram of a top view of an optical cross waveguide unit provided by the present application.

FIG. 2 is a schematic structural diagram of a front view of an optical cross waveguide unit provided by the present application.

FIG. 3 is a top view of another structure of an optical cross waveguide unit provided by the present application.

Numeral description: 1, strip-shaped optical waveguide; 100, equal-width part; 101, widened part; 102, overlapping part; 110, input strip-shaped optical waveguide; 111, output strip-shaped optical waveguide; 2, flat-shaped optical waveguide; 201, the first straight edge; 202, the second straight edge; 203, the third straight edge; 204, the fourth straight edge; 211, the first arc side, 212, the second arc side; 213, the third arc 214, the fourth arc-shaped side surface; 3, the total internal reflection mirror; 311, the first total internal reflection mirror; 312, the second total internal reflection mirror.

Detailed ways

Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary, only used to explain the present invention, and should not be construed as a limitation of the present invention.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "backward", etc. The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation or a specific orientation. construction and operation, and therefore should not be construed as limiting the invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, features defined as "first", "second" may expressly or implicitly include one or more of said features. In the description of the present invention, "plurality" means two or more, unless otherwise expressly and specifically defined.

The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Of course, they are only examples and are not intended to limit the invention. Furthermore, the present disclosure may repeat reference numerals and/or reference letters in different instances for the purpose of simplicity and clarity and not in itself indicative of a relationship between the various embodiments and/or arrangements discussed.

As shown in FIG. 1 and FIG. 2, an optical cross waveguide unit of the present invention includes a flat-shaped optical waveguide 2 and at least two strip-shaped optical waveguide groups, each strip-shaped optical waveguide group includes two strip-shaped optical waveguides 1, The two strip-shaped optical waveguides 1 are the input strip-shaped optical waveguide 110 and the output strip-shaped optical waveguide 111 respectively; the flat-shaped optical waveguide 2 includes at least two total internal reflection mirror groups, the total internal reflection mirror group and the strip-shaped optical waveguide group are one. A corresponding arrangement, each total internal reflection mirror group includes a plurality of total internal reflection mirrors 3, and each total internal reflection mirror group is used to guide all the light waves input by the input strip-shaped optical waveguide 110 in the corresponding strip-shaped optical waveguide group to the corresponding output strip optical waveguide 111;

The output end of the input strip-shaped optical waveguide 110 and the input end of the output strip-shaped optical waveguide 111 protrude below the slab-shaped optical waveguide 2 and have a gap between them and the slab-shaped optical waveguide 2, and the thickness a of the gap is 0.01 μm-0.2 μm .

For the convenience of description, see FIG. 2 , the output end of the input strip-shaped optical waveguide 110 and the input end of the output strip-shaped optical waveguide 111 extend below the plate-shaped optical waveguide 2 , which means that the strip-shaped optical waveguide 1 is in the plate-shaped optical waveguide 2 The projection of the plane on which the lower surface is located overlaps with the lower surface of the flat-shaped optical waveguide 2 (overlapping parts 102 are the output end of the input strip-shaped optical waveguide 110 and the input end of the output strip-shaped optical waveguide 111 respectively). Generally, a Gaussian beam with a wavelength of 1.55 μm commonly used in single-mode optical fiber communication is used for the incident light wave.

Specifically, an optical cross waveguide unit includes a flat-shaped optical waveguide 2 and at least two strip-shaped optical waveguide groups, and the flat-shaped optical waveguide 2 includes at least two total internal reflection mirror groups, wherein the strip-shaped optical waveguide group and the total internal reflection mirror group Each of the mirror groups has at least two, and may be three or four strip-shaped optical waveguide groups and total internal reflection mirror groups, but is not limited to this. and two strip-shaped optical waveguide groups, the slab-shaped optical waveguide includes two total internal reflection mirror groups as an example.

In practical applications, the two strip-shaped optical waveguide groups and the flat-shaped optical waveguide form a double-layer structure, because the output end of the input strip-shaped optical waveguide 110 and the input end of the output strip-shaped optical waveguide 111 protrude below the plate-shaped optical waveguide 2 . , the overlapping portion 102 is affected by the thickness of the gap between the strip-shaped optical waveguide group and the flat-shaped optical waveguide 2 (ie, the coupling distance), and the difference in the coupling distance affects the length of the overlapping portion 102. Generally speaking, the smaller the coupling distance is , the length of the overlapping portion 102 (referring to the distance of the strip-shaped optical waveguide from the protruding point into the flat-shaped optical waveguide to the other end pointing to the flat-shaped optical waveguide) is smaller, and the strip-shaped optical waveguide group and the flat-shaped optical waveguide are The thickness a of the gap between 2 is 0.01 μm-0.2 μm, then the specific range of the length L4 of the corresponding overlapping portion 102 is: 0.2 μm-12 μm; therefore, when the incident light wave is coupled from the input strip-shaped optical waveguide 110 to the flat-shaped optical waveguide 2 The coupling efficiency is high; when the incident light wave is coupled to the slab optical waveguide 2 at the output end of the input strip optical waveguide 110, one of the total internal reflection mirrors 3 reflects all the light waves input from the slab optical waveguide 2, and the other After the internal reflection mirror 3 is reflected, it is collected and coupled to the output strip-shaped optical waveguide 111 again. By setting two strip-shaped optical waveguide groups and two total internal reflection mirror groups, the two incident light waves form a cross in the flat-shaped optical waveguide 2. When the incident light wave propagates in the flat optical waveguide 2, its propagation mode is limited only in the longitudinal direction (thickness direction), and the incident light wave can propagate freely in the lateral direction. The optical waveguide 2 does not contact the rough side walls during propagation, which greatly reduces the loss of light wave energy and ensures the low energy loss of the cross waveguide, thereby improving the propagation efficiency and overall performance of the optical signal in the optical integrated chip.

In some embodiments, as shown in FIGS. 1 and 3 , the flat-shaped optical waveguide 2 of the present application is provided with four straight edges, and the four straight edges are respectively a first straight edge 201 , a second straight edge 202 , and a third straight line The edge 203 and the fourth linear edge 204, the first linear edge 201 is parallel to the third linear edge 203, the second linear edge 202 is parallel to the fourth linear edge 204; two strip-shaped optical waveguides of one strip-shaped optical waveguide group 1 They face the first straight edge 201 and the third straight edge 203 respectively (here, the strip-shaped optical waveguide 1 is disposed facing the straight edge, which means that the strip-shaped optical waveguide 1 is located at the straight edge along the line perpendicular to the straight edge. The direction extends below the plate-shaped optical waveguide 2), that is, the input strip-shaped optical waveguide 110 is facing the first linear edge 201, and the output strip-shaped optical waveguide 111 is facing the third linear edge 203 (it can also be an input strip-shaped optical waveguide 203). The waveguide 110 is facing the third straight edge 203, and the output strip optical waveguide 111 is facing the first straight edge 201). The output end of the input strip-shaped optical waveguide 110 is coupled to the flat-shaped optical waveguide 2, and the total internal reflection mirror 3 guides all the incident light waves of the flat-shaped optical waveguide 2 to the output strip-shaped optical waveguide 111 of the third straight edge 203, so as to realize the incident light wave Spread. The two strip-shaped optical waveguides 1 of the other strip-shaped optical waveguide group face the second straight edge 202 and the fourth straight edge 204 respectively, that is, the input strip-shaped optical waveguide 110 faces the second straight edge 202, and the output strip-shaped light The waveguide 111 is facing the fourth straight edge 204 (it can also be that the input strip optical waveguide 110 is facing the fourth straight edge 204, and the output strip optical waveguide 111 is facing the second straight edge 202). The input strip-shaped optical waveguide 110 of the second straight edge 202 is input, and is coupled to the slab-shaped optical waveguide 2 through the output end of the input strip-shaped optical waveguide 110, and the total internal reflection mirror 3 guides all the incident light waves of the slab-shaped optical waveguide 2 to the fourth optical waveguide 2. The output strip light guide 111 of the straight edge 204 . If the two strip-shaped optical waveguide groups are directly intersected, the width of the intersection of the strip-shaped optical waveguide groups becomes larger due to the single-layer structure. When the incident light wave is input from the input strip-shaped optical waveguide 110, the The sudden change of the center sidewall of the intersection of the optical waveguide group causes a large amount of light wave diffraction, which cannot all output the same incident light wave, and the diffraction of the two incident light waves at the intersection center will lead to signal crosstalk. The present invention separates two strip-shaped optical waveguide groups, and the strip-shaped optical waveguide group and the flat-shaped optical waveguide 2 are double-layered structures, so that the two incident light waves will not have crosstalk between the strip-shaped optical waveguide groups, which The incident light wave forms a cross-wave in the flat-shaped optical waveguide 2, and this structure does not directly cross the existing signal crosstalk like other strip-shaped optical waveguides, and realizes the low crosstalk of the signal of the cross-wave.

Generally, the first linear edge 201 and the third linear edge 203 are perpendicular to the second linear edge 202 and the fourth linear edge 204, so that the two strip-shaped optical waveguides 1 of the same strip-shaped optical waveguide group are parallel to each other , the strip-shaped optical waveguides 1 of the two strip-shaped optical waveguide groups are perpendicular to each other; but not limited to this.

In some embodiments, as shown in FIG. 2 , the width of the equal-width portion 100 at one end of the strip-shaped optical waveguide 1 away from the flat-shaped optical waveguide 2 in the present application remains unchanged. When a Gaussian beam commonly used in single-mode optical fiber communication is used as the incident light wave When the equal width part 100 and the optical wave mode field can be well matched, the widened part 101 of the strip-shaped optical waveguide 1 close to one end of the flat-shaped optical waveguide 2 is provided, and the widened part 101 is from the end facing away from the flat-shaped optical waveguide 2 To the end pointing to the flat-shaped optical waveguide 2, the width gradually increases, in order to reduce the diffraction effect, thereby further reducing the loss; the edge lines on both sides of the widened portion 101 can be straight lines, parabolas, other quadratic function curves or not. Regular shape curve.

Specifically, the total internal reflection mirror 3 is a curved mirror, and the curved mirror is a concave mirror. Since the concave mirror has a light-gathering effect, it can make the parallel light converge at the focus, and can also reflect the light emitted from the focus into parallel light. When the incident light wave is input from the flat optical waveguide 2, the incident light wave is focused by a total internal reflection mirror 3. After that, all of them are reflected to another total internal reflection mirror 3 as parallel light, and the other total internal reflection mirror 3 is focused and then reflected to the output strip-shaped optical waveguide 111 as parallel light again, which further reduces the loss of light wave energy during propagation.

In some embodiments, as shown in FIG. 1 , if the plate-shaped optical waveguide 2 is rectangular, two total internal reflection mirror groups are arranged in the rectangle, and each total internal reflection mirror group is one-to-one with each strip-shaped optical waveguide group Correspondingly, each total internal reflection mirror group includes two total internal reflection mirrors, namely the first total internal reflection mirror 311 and the second total internal reflection mirror 312. When the incident light wave is input from the input strip light waveguide 110, the first total internal reflection mirror 311 The total internal reflection mirror 311 is used to reflect all the incident light waves of the corresponding input strip optical waveguide 110 to the corresponding second total internal reflection mirror 312, and the second total internal reflection mirror 312 is used to reflect the corresponding first total internal reflection mirror The reflected light waves of 311 are all reflected to the corresponding output strip-shaped optical waveguide 111, thereby forming two incident light waves to intersect in the flat-shaped optical waveguide 2. Light waves can greatly reduce diffraction, and the interference between the cross waves is relatively low.

In practical applications, the plate-shaped optical waveguide 2 is not limited to being rectangular. For example, in FIG. 3 , in other embodiments, the plate-shaped optical waveguide 2 further includes four arc-shaped sides, and the four arc-shaped sides are the first arcs respectively. The curved side surface 211, the second curved side surface 212, the third curved side surface 213, the fourth curved side surface 214, each curved side surface is covered with a reflective layer, and the thickness of the coated reflective layer is not less than the total reflection of the light wave Transmission depth, so that each arc-shaped side surface serves as a total internal reflection mirror 3, wherein the first arc-shaped side surface 211 and the third arc-shaped side surface 213 are respectively equivalent to the first total internal reflection mirror 311 and the third total internal reflection mirror group of the same total internal reflection mirror group. Two total internal reflection mirrors 312 ; the second curved side surface 212 and the fourth curved side surface 214 are respectively equivalent to the first total internal reflection mirror 311 and the second total internal reflection mirror 312 of the same total internal reflection mirror group. Compared with the rectangular plate-shaped optical waveguide 2, the plate-shaped optical waveguide 2 is more material-saving, which is beneficial to reduce the cost.

In some embodiments, as shown in FIG. 1 , when a Gaussian beam commonly used in single-mode optical fiber communication is used as the input light wave, the distance from the starting point of the input light wave of the slab optical waveguide 2 to the corresponding first total internal reflection mirror 311 is equal to the Gaussian light wave The Rayleigh distance (that is, the Rayleigh distance of the input light wave), the incident angle and reflection angle of the input light wave of the flat optical waveguide 2 to the total internal reflection mirror 3 are both 45°, and the Gaussian beam can obtain the highest laser gain at this time; The distance from the reflection point of the first total internal reflection mirror 311 to the reflection point of the corresponding second total internal reflection mirror 312 is set to be equal to twice the Rayleigh distance of the Gaussian light wave. The plate-shaped optical waveguide 2 has a rotationally symmetrical shape.

Specifically, both the strip-shaped optical waveguide 1 and the flat-shaped optical waveguide 2 have an outer cladding, the outer cladding is silicon dioxide, and the outer cladding refers to the upper surface and the lower surface of the strip-shaped optical waveguide 1 and the flat-shaped optical waveguide 2 respectively.

In some embodiments, for a Gaussian beam with a wavelength of 1.55 μm, the standard size of the interface of the crossed waveguide element is 0.45 μm*0.22 μm. When a Gaussian beam with a wavelength of 1.55 μm is used as the input light wave, the thickness of the strip optical waveguide 1 is 0.22 μm, and the width L1 of the equal-width portion is 0.45 μm, so that the cross-sectional dimension of the equal-width portion 100 is a standard size, so as to improve the applicability of the optical cross-waveguide element, and the width L1 of the widened portion 102 is set close to the plate-shaped optical waveguide 2 The width L2 of the end face at one end is 1.5 μm, which ensures that the incident light wave can be clearly collected by the total internal reflection mirror 3 when the plate-shaped optical waveguide 2 is incident.

In some embodiments, considering the manufacturing tolerance of the optical waveguide in actual manufacturing, when the length L3 of the widened portion is 5 μm-7 μm, the coupling efficiency of the incident light wave can be improved, and when the length L3 of the widened portion is 5 μm, the incident The coupling efficiency of the light wave reaches 93%. When the length L3 of the widening portion is 6 μm, the coupling efficiency of the incident light wave reaches 97%. When the length L3 of the widening portion is 7 μm, the coupling efficiency of the incident light wave can reach 99%.

，F为高斯光波的瑞利距离（对于波长1.55μm的高斯光束，圆弧面 半径为9μm），可以进一步提高入射光波能量的聚焦能力。 In a specific application, considering the manufacturing tolerance of the optical waveguide in actual manufacturing, the reflection surface of the total internal reflection mirror 3 is an arc surface, and the radius of the arc surface is

, F is the Rayleigh distance of the Gaussian light wave (for a Gaussian beam with a wavelength of 1.55 μm, the radius of the arc surface is 9 μm), which can further improve the focusing ability of the incident light wave energy.

The following is further described by specific examples:

In the first specific embodiment, a Gaussian beam with a wavelength of 1.55 μm commonly used in single-mode optical fiber communication is used as the input light wave. It is found through simulation calculation that when a group of incident light waves propagate in the structure, the energy loss of the light waves is compared. few.

As shown in FIG. 2 , the thickness of the strip-shaped optical waveguide 1 is 0.22 μm, the width L1 of the equal-width portion is 0.45 μm, the width L2 of the end face of the widened portion 101 close to one end of the flat-shaped optical waveguide 2 is 1.5 μm, and the length L3 of the widened portion is 1.5 μm. is 7 μm, the length L4 of the overlapping portion 102 projected by the output end of the input strip-shaped optical waveguide 110 and the output end of the output strip-shaped optical waveguide 111 respectively on the bottom surface of the flat-shaped optical waveguide 2 is 0.4 μm. The gap thickness a with the plate-shaped optical waveguide 2 was 0.02 μm. The incident light wave is input from the equal-width portion 100 of the input strip-shaped optical waveguide 110 and output from the output end of the input optical waveguide 110 (ie, the end face of the widened portion 101 ), so that the coupling efficiency of the incident light wave is high.

，F为高斯光波的瑞利距离，即圆弧面半径为9μ m；且平板形光波导2的输入光波的起点到对应的第一全内反射镜311的反射点的距离F等于 输入高斯光波的瑞利距离，即3.27μm，第一全内反射镜311的反射点到对应的第二全内反射 镜312的反射点的距离等于两倍高斯光波的瑞利距离，即6.54μm。此时两个条形光波导组与 矩形内的两个全内反射镜组的俯视图为旋转对称形状。平板形光波导2的入射光波经第一 全内反射镜311汇集后全部以平行光反射至对应的第二全内反射镜312，第二全内反射镜 312将对应的第一全内反射镜311的反射光全部汇集后再次以平行光反射至对应的输出条 形光波导111，另一个条形光波导组和另一个全内反射镜组以同样的工作方式完成，从而在 平板形光波导2内形成交叉波，且交叉波在平板形光波导2内未直接接触粗糙侧壁，交叉波 在平板形光波导2内仅由全内反射镜3引导传播，大大减少了光波能量的损失，保证了交叉 波导的低能量损耗；并且条形光波导组之间不是直接交叉的，可以大大减少光波信号的串 扰。 The plate-shaped optical waveguide 2 is a rectangle. As shown in Figure 1, two total internal reflection mirror groups are arranged in the rectangle. The reflection surface of the total internal reflection mirror 3 is an arc surface, and the radius of the arc surface is

, F is the Rayleigh distance of the Gaussian light wave, that is, the radius of the arc surface is 9 μm; and the distance F from the starting point of the input light wave of the flat optical waveguide 2 to the corresponding reflection point of the first total internal reflection mirror 311 is equal to the input Gaussian light wave The Rayleigh distance is 3.27 μm, and the distance from the reflection point of the first total internal reflection mirror 311 to the corresponding reflection point of the second total internal reflection mirror 312 is equal to twice the Rayleigh distance of the Gaussian light wave, that is, 6.54 μm. At this time, the top views of the two strip-shaped optical waveguide groups and the two total internal reflection mirror groups in the rectangle are rotationally symmetrical shapes. The incident light waves of the plate-shaped optical waveguide 2 are collected by the first total internal reflection mirror 311 and all reflected as parallel light to the corresponding second total internal reflection mirror 312, and the second total internal reflection mirror 312 will reflect the corresponding first total internal reflection mirror. The reflected light of 311 is all collected and reflected to the corresponding output strip optical waveguide 111 as parallel light again. A cross wave is formed in the flat optical waveguide 2, and the cross wave does not directly contact the rough side wall in the flat optical waveguide 2. The cross wave is only guided and propagated by the total internal reflection mirror 3 in the flat optical waveguide 2, which greatly reduces the loss of light wave energy. The low energy loss of the crossed waveguide is ensured; and the strip-shaped optical waveguide groups are not directly crossed, which can greatly reduce the crosstalk of the light wave signal.

In the second specific embodiment, as shown in FIGS. 2 and 3 , the thickness of the strip-shaped optical waveguide is 0.22 μm, the width L1 of the equal-width portion is 0.45 μm, and the width of the widened portion 102 is close to the end face of one end of the flat-shaped optical waveguide 2 . The width L2 is 1.5 μm, the length L3 of the widened portion is 7 μm, the output end of the input strip-shaped optical waveguide 110 and the output end of the output strip-shaped optical waveguide 111 are respectively projected on the bottom surface of the flat-shaped optical waveguide 2 Length of the overlapping portion 102 L4 are all 0.4 μm, and the gap thickness a between the strip-shaped optical waveguide group and the flat-shaped optical waveguide is 0.02 μm. The incident light wave is input from the equal-width portion 100 of the input strip-shaped optical waveguide 110 and output from the output end of the input strip-shaped optical waveguide 110 (ie, the end face of the widened portion 101 ), so that the coupling efficiency of the incident light wave is high.

The plate-shaped optical waveguide 2 includes four straight edges and four arc-shaped sides, and each arc-shaped side is a circular arc-shaped side, and the four straight edges are the first straight edge 201, the second straight edge 202, The third straight edge 203 and the fourth straight edge 204, the first straight edge 201 is parallel to the third straight edge 203, the second straight edge 202 is parallel to the fourth straight edge 204; the four arc-shaped sides are respectively the first arc-shaped Side 211 , second arc side 212 , third arc side 213 , fourth arc side 214 , each arc side serves as a total internal reflection mirror 3 , and its arc surface radius is 9 μm. It is covered with a reflection layer, and the thickness of the covered reflection layer is not less than the total reflection and transmission depth of the light wave. Because, when the light wave is totally reflected, there will be a certain depth of transmission in the reflective medium. The first arc-shaped side 211 is connected to the first straight edge 201 , the second arc-shaped side 212 is connected to the second straight edge 202 , the third arc-shaped side 213 is connected to the third straight edge 203 , and the fourth arc-shaped side 214 connected with the fourth straight edge 204; wherein, the first arc-shaped side surface 211 and the third arc-shaped side surface 213 are respectively equivalent to the first total internal reflection mirror 311 and the second total internal reflection mirror 312 of the same total internal reflection mirror group; The two arc-shaped side surfaces 212 and the fourth arc-shaped side surface 214 are respectively equivalent to the first total internal reflection mirror 311 and the second total internal reflection mirror 312 of the same total internal reflection mirror group; The optical waveguide 1 is respectively disposed facing the first straight edge 201 and the third straight edge 203 , and the two strip-shaped optical waveguides 1 of the other strip-shaped optical waveguide group are respectively disposed facing the second straight edge 202 and the fourth straight edge 204 .

The distance from the starting point of the input light wave of the flat optical waveguide 2 to the corresponding reflection point of the first arc-shaped side surface 211 is equal to the Rayleigh distance of the input Gaussian light wave, that is, 3.27 μm, and the reflection point of the first arc-shaped side surface 211 to the third The distance of the reflection point of the arcuate side surface 213 and the distance of the reflection point of the second arcuate side surface 212 to the reflection point of the fourth arcuate side surface 214 are equal to twice the Rayleigh distance of the Gaussian light wave, ie 6.54 μm.

When the incident light wave is input from the input strip-shaped optical waveguide 110 and coupled to the flat-shaped optical waveguide 2, the incident light wave of the flat-shaped optical waveguide 2 is completely reflected by the first arc-shaped side 211 to the third arc-shaped side 213, and the third arc-shaped side 213 reflects all the reflected light waves of the first arc-shaped side surface 211 to the corresponding output strip-shaped optical waveguide 111, and another incident light wave of the flat-shaped optical waveguide 2 is completely reflected by the second arc-shaped side surface 212 to the fourth arc-shaped side surface 214, The fourth arc-shaped side surface 214 reflects all the reflected light waves from the second arc-shaped side surface 212 to the corresponding output strip-shaped light waves 111 . The structure can also greatly reduce the loss of light wave energy and ensure low energy loss of the crossed waveguides; and the strip-shaped optical waveguide groups are not directly crossed, which can greatly reduce the crosstalk of light wave signals. In addition, compared with the rectangular plate-shaped optical waveguide 2, the plate-shaped optical waveguide 2 saves more material, which is beneficial to reduce the cost.

In the description of this specification, reference is made to the terms "in the first embodiment," "in the second embodiment," "in some embodiments," "example," "specifically," or "in practice" The description of "in use" or the like means that a particular feature, structure, material, or characteristic described in connection with the described embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The foregoing are merely some of the embodiments of the present invention. For those of ordinary skill in the art, without departing from the inventive concept of the present invention, several modifications and improvements can be made, which all belong to the protection scope of the present invention.

Claims (7)

1. An optical cross waveguide unit, comprising a flat-shaped optical waveguide and at least two strip-shaped optical waveguide groups, each of the strip-shaped optical waveguide groups including two strip-shaped optical waveguides, and the two strip-shaped optical waveguides are respectively It is an input strip-shaped optical waveguide and an output strip-shaped optical waveguide; it is characterized in that the flat-shaped optical waveguide includes at least two total internal reflection mirror groups, and the total internal reflection mirror group and the strip-shaped optical waveguide group are one by one. Correspondingly, each of the total internal reflection mirror groups includes a plurality of total internal reflection mirrors, and each of the total internal reflection mirror groups is used to convert the input strip-shaped optical waveguides in the corresponding strip-shaped optical waveguide groups All input light waves are guided to the corresponding output strip light guides; The output end of the input strip-shaped optical waveguide and the input end of the output strip-shaped optical waveguide protrude below the plate-shaped optical waveguide and have a gap with the plate-shaped optical waveguide, and the thickness of the gap is 0.01μm -0.2μm; The plate-shaped optical waveguide includes four straight edges, the four straight edges are respectively a first straight edge, a second straight edge, a third straight edge and a fourth straight edge, the first straight edge and the The edge of the third straight line is parallel, and the edge of the second straight line is parallel to the edge of the fourth straight line; wherein the two strip-shaped optical waveguides of one of the strip-shaped optical waveguide groups are respectively facing the first linear edge. and the third linear edge, and the two strip-shaped optical waveguides of the other strip-shaped optical waveguide group are respectively disposed opposite to the second linear edge and the fourth linear edge; The plate-shaped optical waveguide is rectangular, and the two total internal reflection mirror groups are arranged in the rectangle, and each of the total internal reflection mirror groups includes two total internal reflection mirrors, which are respectively the first total internal reflection mirror and a second total internal reflection mirror, the first total internal reflection mirror is used to reflect all the incident light waves of the corresponding input strip-shaped optical waveguide to the corresponding second total internal reflection mirror, and the second total internal reflection mirror The internal reflection mirror is used to reflect all the reflected light waves of the corresponding first total internal reflection mirror to the corresponding output strip light waveguide; The distance from the starting point of the input light wave of the flat optical waveguide to the corresponding reflection point of the first total internal reflection mirror is equal to the Rayleigh distance of the Gaussian light wave; the reflection point of the first total internal reflection mirror to the corresponding The distance of the reflection point of the second total internal reflection mirror is equal to twice the Rayleigh distance of the Gaussian light wave. 2 . The optical cross waveguide unit according to claim 1 , wherein the strip-shaped optical waveguide comprises an equal-width portion away from one end of the slab-shaped optical waveguide and a widened portion close to one end of the slab-shaped optical waveguide. 3 . , along the axial direction of the strip-shaped optical waveguide, the width of the equal-width portion does not change, and the width of the widened portion from the end facing away from the flat-shaped optical waveguide to the end pointing to the flat-shaped optical waveguide, the width gradually increase. 3 . The optical cross waveguide unit according to claim 1 , wherein the total internal reflection mirror is a curved mirror, and the curved mirror is a concave mirror. 4 . 4 . The optical cross waveguide unit according to claim 1 , wherein the strip-shaped optical waveguide and the flat-shaped optical waveguide both have an outer cladding, and the outer cladding is silicon dioxide. 5 . 5 . The optical cross waveguide unit according to claim 2 , wherein the strip-shaped optical waveguide has a thickness of 0.22 μm, the width of the equal-width portion is 0.45 μm, and the width of the widened portion is close to the The width of the end face at one end of the slab-shaped optical waveguide was 1.5 μm. 6 . The optical cross waveguide unit according to claim 2 , wherein the length of the widened portion is 5 μm to 7 μm. 7 . 7 . The optical cross waveguide unit according to claim 1 , wherein the reflection surface of the total internal reflection mirror is an arc surface, and the radius of the arc surface is

, F is the Rayleigh distance of the Gaussian light wave.

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