Optical transmission lines and optical connectors

Abstract

This invention provides an optical transmission path capable of compensating for changes in the two-dimensional intensity distribution of signal light generated in an optical waveguide. [Solution] The optical transmission path (1) comprises an optical waveguide (11) and an optical modulation element (121). The phase modulation amount of each cell of the optical modulation element (121) is set to compensate for changes in the two-dimensional intensity distribution of the signal light generated in the optical waveguide (11).

Description

Technical Field

[0001] The present invention relates to an optical transmission path including an optical waveguide. Further, it relates to an optical connector for connecting an optical processor and an optical waveguide.

Background Art

[0002] In order to exceed the limits of electrical processors such as CPUs (Central Processing Units) and GPUs (Graphics Processing Units) that perform calculations electrically, research and development of optical processors that perform calculations optically has been underway. By using an optical processor, calculations can be performed at a higher speed than when using an electrical processor. Technologies contributing to the realization of such an optical processor include, for example, the optical transistor described in Non-Patent Document 1.

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in a system including a plurality of optical processors, when these optical processors are connected by an electrical transmission path, the process of converting an optical signal into an electrical signal becomes a bottleneck, and the calculation speed of the entire system does not increase sufficiently.

[0005] In particular, some optical processors output optical signals that represent two-dimensional data, such as images, using a two-dimensional intensity distribution. When connecting such optical processors via an electrical transmission line, it is necessary to (1) read the m x n two-dimensional data represented by the optical signal, (2) generate m one-dimensional data corresponding to each row of the read two-dimensional data, (3) generate m electrical signals representing each of the m one-dimensional data generated, and (4) sequentially transmit the m generated electrical signals. For this reason, no matter how fast the optical calculations performed by the optical processor are, that high speed cannot be utilized. Therefore, it is preferable to connect such optical processors using an optical transmission line rather than an electrical transmission line.

[0006] However, when using an optical waveguide as the optical transmission path, it is not possible to transmit the optical signal output from the optical processor while maintaining its two-dimensional intensity distribution. This is because the two-dimensional intensity distribution of the optical signal changes during the process of being guided through the optical waveguide.

[0007] One aspect of the present invention has been made in view of the above-mentioned problems, and its objective is to realize an optical transmission path that can compensate for changes in the two-dimensional intensity distribution of signal light generated in an optical waveguide. [Means for solving the problem]

[0008] In one aspect of the present invention, an optical connector is provided for connecting an optical waveguide having a specific structure to an optical processor, comprising an optical modulation element having a plurality of cells whose phase modulation amounts are set independently of each other, wherein one main surface of the optical modulation element is arranged to face one end surface of the optical waveguide, the phase modulation amount of each cell constituting the optical modulation element is set to compensate for a change in the two-dimensional intensity distribution of signal light generated in the optical waveguide, which is determined according to the specific structure, and the optical connector comprises a first recess capable of accommodating the end of the optical waveguide and a second recess capable of accommodating the optical processor, and the optical modulation element is arranged in the space between the first recess and the second recess.

[0009] In another aspect of the present invention, an optical connector is provided for connecting an optical waveguide having a specific structure to an optical processor, comprising an optical modulation element having a plurality of cells whose phase modulation amounts are set independently of each other, wherein one main surface of the optical modulation element is arranged to face one end surface of the optical waveguide, the phase modulation amount of each cell constituting the optical modulation element is set to compensate for a change in the two-dimensional intensity distribution of signal light generated in the optical waveguide, which is determined according to the specific structure, and the optical connector is provided with a microlens array arranged to face one main surface of the optical modulation element.

[0010] In another aspect of the present invention, an optical connector for connecting an optical waveguide having a specific structure to an optical processor is provided, comprising: an optical modulation element having a plurality of cells whose phase modulation amounts can be set independently of each other, wherein one main surface of the optical modulation element is arranged to face one end surface of the optical waveguide; and a control unit that sets the phase modulation amount of each cell constituting the optical modulation element to compensate for a change in the two-dimensional intensity distribution of signal light generated in the optical waveguide, which is determined according to the specific structure, wherein the optical connector comprises a first recess capable of accommodating the end of the optical waveguide and a second recess capable of accommodating the optical processor, and the optical modulation element is arranged in the space between the first recess and the second recess.

[0011] In another aspect of the present invention, an optical connector for connecting an optical waveguide having a specific structure to an optical processor is provided, comprising: an optical modulation element having a plurality of cells whose phase modulation amounts can be set independently of each other, wherein one main surface of the optical modulation element is arranged to face one end surface of the optical waveguide; and a control unit that sets the phase modulation amount of each cell constituting the optical modulation element to compensate for a change in the two-dimensional intensity distribution of signal light generated in the optical waveguide, which is determined according to the specific structure, wherein the optical connector is provided with a microlens array arranged to face one main surface of the optical modulation element. [Effects of the Invention]

[0012] According to one aspect of the present invention, it is possible to realize an optical transmission path that can compensate for changes in the two-dimensional intensity distribution of signal light generated in an optical waveguide. [Brief explanation of the drawing]

[0013] [Figure 1] This is a perspective view showing the configuration of an optical transmission line according to one embodiment of the present invention. [Figure 2] This figure shows the function of the optical modulation element group in the optical transmission path shown in Figure 1. (a) shows a specific example of the two-dimensional intensity distribution of signal light incident on the optical modulation element, and (b), (c), and (d) each show specific examples of the cross-sectional structure of the optical waveguide. [Figure 3] (a) is a plan view showing a first specific example of an optical modulation element provided in the optical transmission line shown in Figure 1. (b) is an enlarged perspective view of a part of that optical modulation element. [Figure 4] (a) is a plan view showing a second specific example of an optical modulation element provided in the optical transmission line shown in Figure 1. (b) is a cross-sectional view of the cell constituting the optical modulation element. [Figure 5] This is a perspective view showing a first modified example of the optical transmission path shown in Figure 1. [Figure 6] This is a perspective view showing a second modified example of the optical transmission path shown in Figure 1. [Figure 7]It is a perspective view showing a third modification example of the optical transmission path shown in FIG. 1. [Figure 8] It is a cross-sectional view showing a first mounting example of the optical transmission path shown in FIG. 1. [Figure 9] It is a perspective view showing a second mounting example of the optical transmission path shown in FIG. 1.

Embodiments for Carrying Out the Invention

[0014] (Configuration of the optical transmission path) The configuration of the optical transmission path 1 according to an embodiment of the present invention will be described with reference to FIG. 1. FIG. 1 is a perspective view showing the configuration of the optical transmission path 1.

[0015] The optical transmission path 1 is a transmission path for transmitting signal light. The optical transmission path 1 is used, for example, for inter-board connection connecting two optical processors mounted on different boards or for intra-board connection connecting two optical processors mounted on the same board. As shown in FIG. 1, the optical transmission path 1 includes an optical waveguide 11 and an optical modulation element group 12.

[0016] The optical waveguide 11 is means for guiding signal light. As the optical waveguide 11, an optical fiber, a substrate-type optical waveguide (for example, a silicon waveguide), or the like can be used. In the present embodiment, an optical fiber is used as the optical waveguide 11.

[0017] The optical modulation element group 12 is means for compensating for changes in the two-dimensional intensity distribution of signal light generated during the process of guiding the optical waveguide 11. The optical modulation element group 12 is composed of at least one optical modulation element. In the present embodiment, an optical modulation element group composed of four optical modulation elements 121 to 124 is used as the optical modulation element group 12. As will be described later, the optical modulation elements 121 to 124 are each composed of a plurality of cells in which the phase modulation amounts can be set independently of each other.

[0018] The optical modulation element 121 is arranged such that one main surface 121a faces one end surface 11a of the optical waveguide 11. The optical modulation element 122 is arranged between the optical modulation element 121 and the optical waveguide 11 in the same manner as the optical modulation element 121. The optical modulation element 123 is arranged between the optical modulation element 122 and the optical waveguide 11 in the same manner as the optical modulation element 121. The optical modulation element 124 is arranged between the optical modulation element 123 and the optical waveguide 11 in the same manner as the optical modulation element 121. Therefore, the signal light Li input from the optical processor to the optical transmission path 1 passes through the optical modulation element 121, the optical modulation element 122, the optical modulation element 123, and the optical modulation element 124 in this order, and then is input to the optical waveguide 11 from the end surface 11a.

[0019] The phase modulation amount of each cell of the optical modulation elements 121 to 124 is set so as to compensate for the change in the two-dimensional intensity distribution of the signal light generated in the process of guiding the optical waveguide 11. In other words, the difference between the two-dimensional intensity distribution of the signal light Li incident on the other main surface 121b of the optical modulation element 121 and the two-dimensional intensity distribution of the signal light Lo emitted from the other end surface 11b of the optical waveguide 11 is set to be smaller than when the optical modulation element group 12 does not exist.

[0020] The setting of the phase modulation amount of each cell of the optical modulation elements 121 to 124 can be realized, for example, using machine learning. In this machine learning, for example, a model that takes the two-dimensional intensity distribution of the signal light Li incident on the main surface 121b of the optical modulation element 121 as an input and the two-dimensional intensity distribution of the signal light Lo emitted from the end surface 11b of the optical waveguide 11 as an output, and includes the phase modulation amount of each cell of the optical modulation elements 121 to 124 as a parameter can be used. By repeating the process of updating the parameters of the model so that the difference between the input and output of the model becomes small for various signal lights (teacher data), it is possible to suitably set the phase modulation amount of each cell of the optical modulation elements 121 to 124.

[0021] Furthermore, an anti-reflective coating (AR) may be formed on the end face 11a of the optical waveguide 11. This reduces the risk that the signal light emitted from the optical modulation element group 12 will be reflected at the end face 11a of the optical waveguide 11 and re-incident to the optical modulation element group 12.

[0022] Furthermore, if the phase modulation amount of each cell of the optical modulation elements 121 to 124 is variable, it is preferable that the optical transmission line 1 includes a control unit (not shown) that sets the phase modulation amount of each cell of the optical modulation elements 121 to 124 as described above.

[0023] Furthermore, in this embodiment, all of the optical modulation elements 121 to 124 are used for the compensation described above, but this is not limited to this. For example, some of the optical modulation elements 121 to 124 may be used for the compensation described above, and the remaining optical modulation elements may be used for other optical calculations. In this case, an optical waveguide equipped with an optical calculation function will be realized.

[0024] The optical modulation elements 121 to 124 may be integrated. For example, four optical diffraction layers formed in a structure that transmits signal light, such as a dried gel, may be used as the optical modulation elements 121 to 124. In this case, it is preferable to use a gel that shrinks while maintaining a similar shape by dehydration shrinkage, such as a gel used in the Implosion Fabrication method. This makes it possible to easily manufacture an optical modulation element group 12 in which the optical modulation elements 121 to 124 are precisely arranged by drying a swollen gel on which four optical diffraction layers have been formed.

[0025] (Function of the optical modulation element group) The function of the optical modulation element group 12 in the optical transmission path 1 will be explained with reference to Figure 2. In Figure 2, (a) shows a specific example of the two-dimensional intensity distribution of signal light Li incident on the optical modulation element 121, and (b), (c), and (d) show specific examples of the cross-sectional structure of the optical waveguide 11, respectively. Here, we consider the case where the two-dimensional intensity distribution of signal light L1 has a 4×4 cell structure, as shown in Figure 2(a).

[0026] In the specific example shown in Figure 2(b), the optical waveguide 11 has a single core 111 whose cross-sectional area is approximately the same as the beam cross-sectional area of ​​the signal light Li. In this case, the entire signal light Li is coupled to the core 111 of the optical waveguide 11. Therefore, the two-dimensional intensity distribution of the signal light Li changes mainly due to guidance through the core 111. Factors contributing to this change include, for example, the disruption of the two-dimensional intensity distribution due to interference between the signal light Li emitted from each cell of the optical modulation element 124 and propagating while spreading inside the core 111, or due to total internal reflection at the boundary between the core 111 and the cladding 112. The phase modulation amount of each cell of the optical modulation elements 121 to 124 is set to compensate for this change. Therefore, the two-dimensional intensity distribution of the signal light Lo output from the end face 11b of the optical waveguide 11 is closer to the two-dimensional intensity distribution of the signal light Li input to the main surface 121b of the optical modulation element 121 compared to the case where the optical modulation element group 12 does not exist.

[0027] In the specific example shown in Figure 2(c), the optical waveguide 11 has 16 cores 111, each with a cross-sectional area approximately 1 / 16 of the beam cross-sectional area of ​​the signal light Li. In this case, one cell's worth of signal light Li is coupled to each core 111 of the optical waveguide 11. Therefore, the two-dimensional intensity distribution of the signal light Li changes mainly due to crosstalk occurring between adjacent cores 111. The phase modulation amount of each cell of the optical modulation elements 121 to 124 is set to compensate for this change. Consequently, the two-dimensional intensity distribution of the signal light Lo output from the end face 11b of the optical waveguide 11 is closer to the two-dimensional intensity distribution of the signal light Li input to the main surface 121b of the optical modulation element 121 compared to the case where the optical modulation element group 12 is absent.

[0028] In the specific example shown in Figure 2(d), the optical waveguide 11 has four cores 111, each with a cross-sectional area approximately 1 / 4 that of the beam cross-sectional area of ​​the signal light Li. In this case, four cells of signal light Li are coupled to each core 111 of the optical waveguide 11. Therefore, the two-dimensional intensity distribution of the signal light Li is affected mainly by changes caused by guiding through each core 111 and by crosstalk between adjacent cores 111. The phase modulation amount of each cell of the optical modulation elements 121 to 124 is set to compensate for these changes. Consequently, the two-dimensional intensity distribution of the signal light Lo output from the end face 11b of the optical waveguide 11 is closer to the two-dimensional intensity distribution of the signal light Li input to the main surface 121b of the optical modulation element 121 compared to the case where the optical modulation element group 12 is absent.

[0029] (Specific example of an optical modulation element 1) A first specific example of the optical modulation elements 121 to 124 will be described with reference to Figure 3. Here, we will focus on optical modulation element 121, but optical modulation elements 122 to 124 are configured similarly. Figure 3(a) is a plan view of the optical modulation element 121 according to this specific example. Figure 3(b) is an enlarged perspective view of a part of the optical modulation element 121 according to this specific example (the part enclosed by the dotted line in Figure 3(a)).

[0030] As shown in Figure 3(a), the optical modulation element 121 is composed of a plurality of microcells C, each with independently set phase modulation amounts. When signal light is incident on the optical modulation element 121, the phase-modulated signal light in each microcell C interferes with each other, thereby performing a predetermined optical calculation (transformation of a two-dimensional intensity distribution according to predetermined transformation rules). The phase modulation amount of each microcell C may be variable or fixed, but in this specific example, it is fixed.

[0031] In this specification, "microcell" refers to a cell with a size of less than 10 μm, for example. "Cell size" refers to the square root of the cell's area. For example, if the planar shape of microcell C is square, the cell size of microcell C is the length of one side of microcell C. The lower limit of the cell size of microcell C is, for example, 1 nm.

[0032] The optical modulation element 121 illustrated in Figure 3(a) is composed of 200 × 200 microcells C arranged in a matrix. The planar shape of each microcell C is a 500 nm × 500 nm square, and the planar shape of the optical modulation element 121 is a 100 μm × 100 μm square.

[0033] (1) The phase modulation amount of microcell C can be set independently for each cell by setting the thickness of each microcell C independently, or (2) the refractive index of each microcell C independently. In this specific example, method (1), which can be realized by nanoimprint, is employed. In this case, each microcell C is composed of a rectangular pillar with a square base where the length of each side is equal to the cell size, as shown in Figure 3(b). In this case, the phase modulation amount of the signal light transmitted through each microcell C is determined according to the height of the pillar that constitutes that microcell C. That is, the phase modulation amount of microcell C composed of tall pillars is large, and the phase modulation amount of microcell C composed of short pillars is small.

[0034] (Specific example of an optical modulation element 2) A second specific example of the optical modulation elements 121 to 124 will be described with reference to Figure 4. Here, we will focus on optical modulation element 121, but optical modulation elements 122 to 124 are configured similarly. Figure 4(a) is a plan view of the optical modulation element 121 according to this specific example. Figure 4(b) is a cross-sectional view of the cell C constituting the optical modulation element 121 according to this specific example.

[0035] As shown in Figure 4(a), the optical modulation element 121 is composed of a plurality of microcells C, each with independently set phase modulation amounts. When signal light is incident on the optical modulation element 121, the phase-modulated signal light in each microcell C interferes with each other, thereby performing a predetermined optical calculation. The phase modulation amount of each microcell C may be variable or fixed, but in this specific example, it is variable.

[0036] The optical modulation element 121 illustrated in Figure 4(a) is composed of 200 × 200 microcells C arranged in a matrix. The planar shape of each microcell C is a 500 nm × 500 nm square, and the planar shape of the optical modulation element 121 is a 100 μm × 100 μm square.

[0037] Each microcell C constituting the optical modulation element 121 can be composed of, for example, a first polarizer C11, a second polarizer C12, a first electrode C13, a magnetization free layer C14, an insulating layer C15, a magnetization fixed layer C16, and a second electrode C17, as shown in Figure 4(b).

[0038] The first polarizer C11 and the second polarizer C12 are arranged facing each other. The first electrode C13, the magnetization free layer C14, the insulating layer C15, the magnetization fixed layer C16, and the second electrode C17 are stacked in this order and sandwiched between the first polarizer C11 and the second polarizer C12. Here, the stacking direction of the first electrode C13, the magnetization free layer C14, the insulating layer C15, the magnetization fixed layer C16, and the second electrode C17 is perpendicular to the stacking direction of the first polarizer C11 and the second polarizer C12. As a result, the first side surface of the magnetization free layer C14 is in surface contact with the first polarizer C11, and the second side surface of the magnetization free layer C14 facing the first side surface is in surface contact with the second polarizer C12. The signal light L (1) enters the magnetized free layer C14 via the first polarizer C11, (2) propagates within the magnetized free layer C14, and (3) exits the magnetized free layer C14 via the second polarizer C12.

[0039] The magnetization free layer C14 is made of, for example, a soft magnetic material having conductivity and light transmission (e.g., CoFeB). The magnetization fixed layer C16 is made of, for example, a hard magnetic material having conductivity (e.g., permalloy). The first polarizer C11 and the second polarizer C12 are polarizers selected that selectively transmit polarization components whose polarization direction P is parallel to the magnetization direction M of the magnetization fixed layer C16. Figure 4(b) illustrates the case where the magnetization direction M and the polarization direction P are parallel to both the main surface of the first polarizer C11 and the main surface of the magnetization fixed layer C16.

[0040] When a potential difference is applied between the first electrode C13 and the second electrode C17, a spin current (a flow of spin-polarized electrons) is injected from the magnetized fixed layer C16 to the magnetized free layer C14 via the insulating layer C15 due to the tunneling effect, and magnetization occurs in the magnetized free layer C14. Here, the magnetization that occurs in the magnetized free layer C14 is parallel to the magnetization direction M of the magnetized fixed layer C16, that is, parallel to the polarization direction P of the signal light incident on the magnetized free layer C14 via the first polarizer C11. Therefore, the phase of the signal light is delayed by the transverse Kerr effect as it propagates through the magnetized free layer C14.

[0041] Here, the amount of phase change of the signal light in cell C is determined by the magnitude of the magnetization generated in the magnetized free layer C14. Furthermore, the magnitude of the magnetization generated in the magnetized free layer C14 is determined by the magnitude of the spin current injected into the magnetized free layer C14. In addition, the magnitude of the spin current injected into the magnetized free layer C14 is determined by the potential difference applied between the first electrode C13 and the second electrode C17. Therefore, by controlling the potential difference applied between the first electrode C13 and the second electrode C17, the amount of phase modulation of cell C can be controlled (set to a desired value).

[0042] In this specific example, a cell C having a configuration similar to that of an STT (Spin Transfer Torque) type MRAM (Magnetoresistive Random Access Memory) has been described, but the explanation is not limited to this. For example, a cell C having a configuration similar to that of an SOT (Spin Orbit Torque) type MRAM may be used. Such a cell C can be realized, for example, by removing the insulating layer C15, the magnetization fixed layer C16, and the second electrode C17 from the structure shown in Figure 4(b). In this case, for example, by including a heavy metal in the first electrode C13 and applying a pulse voltage or pulse current to the first electrode C13, a spin current can be efficiently injected into the magnetization free layer C14.

[0043] (Example 1 of optical transmission line) A first modified example of optical transmission path 1 (hereinafter referred to as "optical transmission path 1A") will be described with reference to Figure 5. Figure 5 is a perspective view showing the configuration of optical transmission path 1A.

[0044] The difference between optical transmission path 1A and optical transmission path 1 lies in the assumed direction of signal light transmission. Specifically, in optical transmission path 1, forward signal light incident on the main surface 121b of the optical modulation element 121 is assumed, whereas in optical transmission path 1A, backward signal light incident on the end surface 11b of the optical waveguide 11 is assumed.

[0045] Therefore, in the optical transmission path 1A, the phase modulation amount of each cell of the optical modulation elements 121 to 124 is set such that the difference between the intensity distribution of signal light Li incident on the end face 11b of the optical waveguide 11 and the intensity distribution of signal light Lo emitted from the main face 121b of the optical modulation element 121 is smaller than when the optical modulation element group 12 is not present. This makes it possible to compensate for changes in the two-dimensional intensity distribution of the backward signal light occurring in the optical waveguide 11.

[0046] (Modified example of optical transmission line 2) A second modified example of optical transmission path 1 (hereinafter referred to as "optical transmission path 1B") will be described with reference to Figure 6. Figure 6 is a perspective view showing the configuration of optical transmission path 1B.

[0047] The difference between optical transmission path 1B and optical transmission path 1 lies in the assumed direction of signal light transmission. Specifically, optical transmission path 1B assumes both forward signal light incident on the main surface 121b of the optical modulation element 121 and backward signal light incident on the end surface 11b of the optical waveguide 11.

[0048] Therefore, in the optical transmission path 1B, the phase modulation amount of each cell of optical modulation elements 121 to 124 is set such that (1) the difference between the two-dimensional intensity distribution of signal light L1i incident on the main surface 121b of optical modulation element 121 and the two-dimensional intensity distribution of signal light L1o emitted from the end surface 11b of the optical waveguide 11 is smaller than when the optical modulation element group 12 is absent, and (2) the difference between the two-dimensional intensity distribution of signal light L2i incident on the end surface 11b of the optical waveguide 11 and the two-dimensional intensity distribution of signal light L2o emitted from the main surface 121b of optical modulation element 121 is smaller than when the optical modulation element group 12 is absent. This makes it possible to both pre-compensate for changes in the two-dimensional intensity distribution of forward signal light occurring in the optical waveguide 11 and post-compensate for changes in the two-dimensional intensity distribution of backward signal light occurring in the optical waveguide 11.

[0049] Furthermore, it is preferable that the forward signal light incident on the main surface 121b of the optical modulation element 121 and the backward signal light incident on the end surface 11b of the optical waveguide 11 are signal lights with different polarization directions. This makes it easier to set the phase modulation amount of each cell of the optical modulation elements 121 to 124 so as to satisfy both conditions (1) and (2) described above.

[0050] Furthermore, it is preferable that an anti-reflective coating (AR) is formed on the end face 11a of the optical waveguide 11. This reduces the risk that the signal light emitted from the optical modulation element group 12 will be reflected at the end face 11a of the optical waveguide 11 and re-incident to the optical modulation element group 12.

[0051] (Modification example of optical waveguide 3) A third modified example of optical transmission path 1 (hereinafter referred to as "optical transmission path 1C") will be described with reference to Figure 7. Figure 7 is a perspective view showing the configuration of optical transmission path 1C.

[0052] The difference between optical transmission path 1C and optical transmission path 1 is the addition of an optical modulation element group 13. Similar to the optical modulation element group 12, the optical modulation element group 13 is a means for compensating for changes in the two-dimensional intensity distribution of the signal light that occur during the guidance process of the optical waveguide 11, and is composed of at least one optical modulation element. In this modified example, the optical modulation element group 13 is composed of four optical modulation elements 131 to 134. Similar to the optical modulation elements 121 to 124, the optical modulation elements 131 to 134 are composed of multiple cells in which the phase modulation amount can be set independently of each other.

[0053] The phase modulation amount of each cell of optical modulation elements 121-124 and 131-134 is set such that the difference between the two-dimensional intensity distribution of signal light Li incident on the main surface 121b of optical modulation element 121 and the two-dimensional intensity distribution of signal light Li emitted from the end surface 131b of optical modulation element 131 is smaller than when optical modulation element groups 12 and 13 are not present. This makes it possible to pre- and post-compensate for changes in the two-dimensional intensity distribution of forward signal light occurring in the optical waveguide 11.

[0054] In this case, it is preferable that an anti-reflective coating AR is formed on the end face 11a of the optical waveguide 11. This reduces the risk that the signal light emitted from the optical modulation element group 12 will be reflected at the end face 11a of the optical waveguide 11 and re-incident to the optical modulation element group 12.

[0055] Furthermore, the phase modulation amount of each cell of optical modulation elements 121-124 and 131-134 may be set such that (1) the difference between the two-dimensional intensity distribution of signal light Li incident on the main surface 121b of optical modulation element 121 and the two-dimensional intensity distribution of signal light Li emitted from the end surface 131b of optical modulation element 131 is smaller than when optical modulation element group 12 and optical modulation element group 13 are absent, and (2) the difference between the two-dimensional intensity distribution of signal light (not shown) incident on the end surface 131b of optical modulation element 131 and the two-dimensional intensity distribution of signal light (not shown) emitted from the main surface 121b of optical modulation element 121 is smaller than when optical modulation element group 12 and optical modulation element group 13 are absent. This enables pre- and post-compensation for changes in the two-dimensional intensity distribution of forward signal light generated in the optical waveguide 11, as well as pre- and post-compensation for changes in the two-dimensional intensity distribution of backward signal light generated in the optical waveguide 11.

[0056] In this case, it is preferable that an anti-reflective coating (not shown) is also formed on the end face 11b of the optical waveguide 11. This reduces the risk that signal light emitted from the optical modulation element group 13 will be reflected at the end face 11b of the optical waveguide 11 and re-incidentated into the optical modulation element group 13.

[0057] In this modified example, both the optical modulation element group 12 and the optical modulation element group 13 are used for the compensation described above, but the invention is not limited to this. For example, the optical modulation element group 12 may be used for the compensation described above, and the optical modulation element group 13 may be used for another optical calculation. In this case, an optical waveguide equipped with an optical calculation function will be realized.

[0058] (Example of optical transmission line implementation) An example of the implementation of optical transmission line 1 will be explained with reference to Figure 8. Figure 8 is a cross-sectional view showing a first implementation example of optical transmission line 1.

[0059] In this implementation example, the end of the optical waveguide 11 (optical fiber) is inserted into a cylindrical ferrule F. The ferrule F is made of, for example, zirconia. Of the ends of the ferrule F, the end on the side of the end face 11a of the optical waveguide 11 may be tapered, as shown in Figure 8. In addition, a flange G may be provided at the end of the ferrule F opposite to the end face 11a of the optical waveguide 11.

[0060] Furthermore, in this implementation example, the optical modulation element group 12 is housed in the optical connector C. The optical connector C is provided with a recess C1 that houses the end of the optical waveguide 11 together with the ferrule F, and a recess C2 that houses the protrusion P1 of the optical processor P. The optical modulation element group 12 is arranged in the space between recess C1 and recess C2.

[0061] According to this implementation example, the optical processor P and the optical waveguide 11 can be easily connected via the optical connector C.

[0062] Furthermore, if the phase modulation amount of each cell of the optical modulation elements 121 to 124 is variable, a configuration may be adopted in which the phase modulation amount of each cell of the optical modulation elements 121 to 124 is set to a phase modulation amount corresponding to the connected optical waveguide 11. This makes it possible to appropriately compensate for changes in the two-dimensional intensity distribution of the signal light generated in the optical waveguide 11, regardless of the type of optical fiber. For example, if phase modulation amounts for an optical fiber with a length of 1 m, phase modulation amounts for an optical fiber with a length of 2 m, etc. are prepared in advance, it becomes possible to appropriately compensate for changes in the two-dimensional intensity distribution of the signal light generated in the optical waveguide 11, regardless of the length of the optical fiber. In this case, the optical connector C may include a control unit (not shown) for setting the phase modulation amount of each cell of the optical modulation elements 121 to 124.

[0063] Furthermore, as shown in Figure 9, a microlens array L may be added downstream of the optical modulation element group 12. This makes it possible to more reliably guide the signal light that has passed through the optical modulation element group 12 to each core of the optical waveguide 11.

[0064] (summary) In an optical transmission path according to Embodiment 1 of the present invention, the optical waveguide and an optical modulation element having a plurality of cells whose phase modulation amounts are set independently of each other, wherein one main surface of the optical modulation element is arranged to face one end surface of the optical waveguide, and the phase modulation amount of each cell constituting the optical modulation element is set to compensate for changes in the two-dimensional intensity distribution of the signal light generated in the optical waveguide.

[0065] According to the above configuration, it is possible to realize an optical transmission path that can compensate for changes in the two-dimensional intensity distribution of signal light generated in the optical waveguide.

[0066] In the optical transmission path according to embodiment 2 of the present invention, in addition to the configuration of embodiment 1, the phase modulation amount of each cell constituting the optical modulation element is set such that the difference between the two-dimensional intensity distribution of the signal light incident on the other main surface of the optical modulation element and the two-dimensional intensity distribution of the signal light emitted from the other end surface of the optical waveguide is smaller than when the optical modulation element is absent.

[0067] According to the above configuration, it is possible to realize an optical transmission path that can compensate for changes in the two-dimensional intensity distribution occurring in the optical waveguide with respect to the signal light incident on the other main surface of the optical modulation element.

[0068] In the optical transmission path according to embodiment 3 of the present invention, in addition to the configuration of embodiment 1 or 2, an anti-reflective coating is formed on one end face of the optical waveguide.

[0069] With the above configuration, the risk of signal light emitted from the optical modulation element being reflected at the end face of the optical waveguide and re-entering the optical modulation element can be reduced.

[0070] In the optical transmission path according to embodiment 4 of the present invention, in addition to the configuration of embodiments 1 to 3, the phase modulation amount of each cell constituting the optical modulation element is set such that the difference between the two-dimensional intensity distribution of the signal light incident from the other end face of the optical waveguide and the two-dimensional intensity distribution of the signal light emitted from the other main face of the optical modulation element is smaller than in the case where the optical modulation element is not present.

[0071] According to the above configuration, it is possible to realize an optical transmission path that can compensate for changes in the two-dimensional intensity distribution occurring in the optical waveguide with respect to signal light incident on the other end face of the optical waveguide.

[0072] In the optical transmission path according to aspect 5 of the present invention, in addition to the configuration of aspect 1, a further configuration is adopted in which there is another optical modulation element having a plurality of cells in which the phase modulation amount can be set independently of each other, and one of the main surfaces of the optical waveguide is arranged to face the other end surface of the optical waveguide.

[0073] According to the above configuration, by using both one optical modulation element and the other optical modulation element to compensate for changes in the two-dimensional intensity distribution of the signal light generated in the optical waveguide, it is possible to realize an optical transmission path that can perform such compensation with greater accuracy. Furthermore, by using one optical modulation element to compensate for changes in the two-dimensional intensity distribution of the signal light generated in the optical waveguide, and using the other optical modulation element for a specific optical calculation, it is possible to realize an optical transmission path that can perform both the compensation and the optical calculation.

[0074] In the optical transmission line according to embodiment 6 of the present invention, in addition to the configuration of embodiment 5, the phase modulation amount of each cell constituting the optical modulation element and the other optical modulation element is set such that the difference between the two-dimensional intensity distribution of signal light incident on the other main surface of the optical modulation element and the two-dimensional intensity distribution of signal light emitted from the other main surface of the other optical modulation element is smaller than when the optical modulation element and the other optical modulation element are not present.

[0075] With the above configuration, it is possible to realize an optical transmission path that can more accurately compensate for changes in the two-dimensional intensity distribution occurring in the optical waveguide with respect to the signal light incident on the other main surface of the optical modulation element.

[0076] In the optical transmission path according to aspect 7 of the present invention, in addition to any of the configurations of aspects 1 to 6, the optical waveguide employs a configuration in which the signal light is guided using a single core.

[0077] According to the above configuration, it is possible to realize an optical transmission path that can compensate for changes in the two-dimensional intensity distribution of signal light caused by total internal reflection at the core-cladding boundary in an optical waveguide.

[0078] In the optical transmission path according to aspect 8 of the present invention, in addition to the configuration of any of aspects 1 to 6, the optical waveguide employs a configuration in which the signal light is guided using a plurality of cores.

[0079] According to the above configuration, it is possible to realize an optical transmission path that can compensate for changes in the two-dimensional intensity distribution of signal light caused by crosstalk between adjacent cores in an optical waveguide.

[0080] In the optical transmission line according to aspect 9 of the present invention, the configuration includes an optical waveguide, an optical modulation element having a plurality of cells whose phase modulation amounts can be set independently of each other, wherein one main surface of the optical modulation element is arranged to face one end surface of the optical waveguide, and a control unit that sets the phase modulation amount of each cell constituting the optical modulation element to compensate for changes in the two-dimensional intensity distribution of signal light generated in the optical waveguide.

[0081] According to the above configuration, it is possible to realize an optical transmission path that can compensate for changes in the two-dimensional intensity distribution of signal light generated in the optical waveguide.

[0082] In an optical connector according to embodiment 10 of the present invention, an optical connector for connecting an optical waveguide and an optical processor is provided, comprising an optical modulation element having a plurality of cells in which the phase modulation amounts are set independently of each other, wherein one main surface of the optical modulation element is arranged to face one end surface of the optical waveguide, and the phase modulation amount of each cell constituting the optical modulation element is set to compensate for changes in the two-dimensional intensity distribution of the signal light generated in the optical waveguide.

[0083] By connecting the optical waveguide and the optical processor using the optical connector described above, changes in the two-dimensional intensity distribution of the signal light generated in the optical waveguide can be compensated for.

[0084] In an optical connector according to aspect 11 of the present invention, an optical connector for connecting an optical waveguide and an optical processor is provided, comprising: an optical modulation element having a plurality of cells whose phase modulation amounts can be set independently of each other, wherein one main surface of the optical modulation element is arranged to face one end surface of the optical waveguide; and a control unit that sets the phase modulation amount of each cell constituting the optical modulation element to compensate for changes in the two-dimensional intensity distribution of signal light generated in the optical waveguide.

[0085] By connecting the optical waveguide and the optical processor using the optical connector described above, changes in the two-dimensional intensity distribution of the signal light generated in the optical waveguide can be compensated for.

[0086] (Additional notes) The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means included in the embodiments described above are also included within the technical scope of the present invention. [Explanation of Symbols]

[0087] 1 Optical transmission path 11 Optical waveguide 12 Optical Modulation Element Group 121-124 Optical Modulators 13 Optical Modulation Element Group 131-134 Optical Modulators P Optical Processor C Optical Connector

Claims

1. An optical connector for connecting an optical waveguide having a specific structure to an optical processor, An optical modulation element having a plurality of cells in which the phase modulation amount is set independently of each other, comprising an optical modulation element in which one main surface is arranged to face one end surface of the optical waveguide, The phase modulation amount of each cell constituting the optical modulation element is set to compensate for a change in the two-dimensional intensity distribution of the signal light generated in the optical waveguide, which is determined according to the specific structure. The optical connector comprises a first recess capable of accommodating the end of the optical waveguide and a second recess capable of accommodating the optical processor. The optical modulation element is positioned in the space between the first recess and the second recess. An optical connector characterized by the following features.

2. An optical connector for connecting an optical waveguide having a specific structure to an optical processor, An optical modulation element having a plurality of cells in which the phase modulation amount is set independently of each other, comprising an optical modulation element in which one main surface is arranged to face one end surface of the optical waveguide, The phase modulation amount of each cell constituting the optical modulation element is set to compensate for a change in the two-dimensional intensity distribution of the signal light generated in the optical waveguide, which is determined according to the specific structure. The optical connector includes a microlens array arranged to face one of the main surfaces of the optical modulation element. An optical connector characterized by the following features.

3. An optical connector for connecting an optical waveguide having a specific structure to an optical processor, An optical modulation element having a plurality of cells in which the phase modulation amount can be set independently of each other, wherein one main surface of the optical modulation element is arranged to face one end surface of the optical waveguide, The optical modulation element includes a control unit that sets the phase modulation amount of each cell constituting the optical modulation element to compensate for a change in the two-dimensional intensity distribution of the signal light generated in the optical waveguide, which is determined according to the specific structure. The optical connector comprises a first recess capable of accommodating the end of the optical waveguide and a second recess capable of accommodating the optical processor. The optical modulation element is positioned in the space between the first recess and the second recess. An optical connector characterized by the following features.

4. An optical connector for connecting an optical waveguide having a specific structure to an optical processor, An optical modulation element having a plurality of cells in which the phase modulation amount can be set independently of each other, wherein one main surface of the optical modulation element is arranged to face one end surface of the optical waveguide, The optical modulation element includes a control unit that sets the phase modulation amount of each cell constituting the optical modulation element to compensate for a change in the two-dimensional intensity distribution of the signal light generated in the optical waveguide, which is determined according to the specific structure. The optical connector includes a microlens array arranged to face one of the main surfaces of the optical modulation element. An optical connector characterized by the following features.

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