JP2006058499A - Optical waveguide device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical functional circuit that has a degree of freedom in setting an optical path and that has reduced cross talk and is small-sized. <P>SOLUTION: The optical waveguide device is structured with a waveguide which is composed of a clad layer formed on a substrate and a core part embedded in the clad layer. The core part includes a pixel shape part 101 defined by a plurality of scattered points with a refractive index lower than that of the waveguide. The core part is equipped with waveguide type passive elements 102, 103 optically coupling a port demarcated by the pixel shape part 101 to the port of the substrate 100. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical waveguide device, and more particularly to an optical waveguide device to which a holographic wave transmission medium that transmits waves holographically by multiple scattering according to a two-dimensional refractive index distribution is applied.

  In the optical communication field, integrated optical components using an optical waveguide structure have been developed as an optical circuit that can easily realize branching and interference of light. Integrated optical components that utilize the properties of light waves make it easy to manufacture optical interferometers by adjusting the optical waveguide length, and to easily integrate optical components by applying circuit processing technology in the semiconductor field. Become.

  Such an optical waveguide structure is an “optical confinement structure” that realizes spatial light confinement of light propagating through the optical waveguide by utilizing a spatial distribution of refractive index. In order to configure an optical circuit, each component is connected in a cascade using an optical wiring or the like. For this reason, the optical path length of the optical waveguide circuit must be longer than the optical path length required for causing an interference phenomenon in the optical circuit, and as a result, the optical circuit itself becomes extremely large. There was a problem.

For example, taking a typical arrayed waveguide grating as an example, light of multiple wavelengths (λ _j ) input from the input port is repeatedly demultiplexed and combined by a star coupler having a slab waveguide. The output light is output from the output port, but the optical path length required for demultiplexing the light with a resolution of about one thousandth of the wavelength is several tens of thousands of the wavelength of the light propagating through the waveguide. Moreover, it is also necessary to perform processing for providing a wave plate for correcting circuit characteristics depending on the polarization state, including waveguide patterning of an optical circuit (see, for example, Non-Patent Document 1).

  In order to reduce the size of the optical circuit, it is necessary to strongly confine light in the waveguide. Therefore, the optical waveguide needs to have a very large refractive index difference. For example, in a conventional step index type optical waveguide, the optical waveguide is designed so as to have a spatial distribution of the refractive index so that the relative refractive index difference becomes a value larger than 0.1%. When optical confinement is performed using such a large refractive index difference, the degree of freedom in circuit configuration is limited. In particular, even if the refractive index difference in the optical waveguide is to be realized by local ultraviolet irradiation, the thermo-optic effect, or the electro-optic effect, the obtained refractive index variation is at most about 0.1%. When changing the propagation direction of light, the direction must be gradually changed along the optical path of the optical waveguide, and the optical circuit length is inevitably extremely long. As a result, miniaturization of the optical circuit is reduced. It becomes difficult.

Y. Hibino, “Passive optical devices for photonic networks”, IEIC Trans. Commun., Vol.E83-B No. 10, (2000).

  Therefore, a wave transmission medium that is smaller than a conventional optical circuit using an optical waveguide circuit or a holographic circuit and has a gentle refractive index distribution, that is, sufficiently high-efficiency optical signal control even with a small refractive index difference is used. As a result, a highly efficient and compact optical circuit is realized. However, the wave transmission medium propagates the optical signal from the input port to the output port while performing multiple scattering by the refractive index of each virtual pixel defined by the virtual mesh. In this way, since the propagation is performed using the interference effect, there is a problem that the optical path cannot have a large angle and the crosstalk is large.

  Further, the mesh-shaped pixels near the input port and the output port in the wave transmission medium function as a kind of lens, which causes a problem that the circuit length becomes long.

  The present invention has been made in view of such problems. The object of the present invention is to apply a holographic wave transmission medium, to have a freedom in setting an optical path, to have a small crosstalk, and to be a small optical functional circuit. Is to provide.

  In order to achieve such an object, the present invention includes a waveguide comprising a clad layer formed on a substrate and a core portion embedded in the clad layer. In the optical waveguide device, the core portion includes a pixel shape portion defined by a plurality of scattering points having a refractive index lower than that of the waveguide, and includes a port defined in the pixel shape portion and a port of the substrate. A waveguide passive element that is optically coupled is provided.

  According to a second aspect of the present invention, in the waveguide passive element according to the first aspect, the beam diameter of light at the port of the substrate is enlarged to obtain the beam diameter of light at the port of the pixel shape portion. It consists of a mirror.

  According to a third aspect of the present invention, in the waveguide passive element according to the first aspect, the beam diameter of light at the port of the substrate is enlarged to obtain the beam diameter of light at the port of the pixel shape portion. It consists of a waveguide lens.

  According to a fourth aspect of the present invention, the guided wave passive element according to the first aspect is a pixel-shaped portion defined by a plurality of scattering points having a refractive index lower than that of the waveguide, and the port of the substrate The beam diameter of the light is enlarged to obtain the light beam diameter at the port of the pixel shape portion.

  As described above, according to the present invention, by combining a holographic wave transmission medium and a waveguide passive element, there is a degree of freedom in optical path setting, a small crosstalk, and a small optical functional circuit is realized. It becomes possible.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The optical waveguide device of this embodiment controls the optical path of guided light by a holographic wave transmission medium. The holographic wave transmission medium is defined by a plurality of scattering points having a refractive index lower than that of the waveguide, and transmits a wave to the holographic by multiple scattering according to a two-dimensional refractive index distribution.

  First, the basic concept of the wave transmission medium used in the present invention will be described. Here, since it is applied to an optical circuit, the “wave” propagating in the wave transmission medium is “light”. The theory relating to the wave transmission medium specifies the characteristics of the medium based on a general wave equation, and can also hold in principle in general waves. In order to input a coherent light pattern and output a desired light pattern, the wave transmission medium has a phase difference between forward propagation light and back propagation light propagating in the wave transmission medium. The refractive index distribution is determined so as to be small even at the location. A desired light pattern is output by repeatedly repeating holographic control at a local level according to the refractive index distribution.

With reference to FIG. 1, the basic structure of the wave transmission medium according to the present embodiment will be described. As shown in FIG. 1A, an optical circuit design area 1-1 constituted by a wave transmission medium exists in the optical circuit board 1. One end face of the optical circuit is an incident surface 2-1 on which the input light 3-1 is incident. The input light 3-1 propagates through the optical circuit having a spatial refractive index distribution composed of the wave transmission medium while being subjected to multiple scattering, and is output as the output light 3-2 from the output surface 2-2 which is the other end face. Is output. Coordinate z in FIG. 1 (a), the coordinates (z = 0 is the incident surface, z = z _e is output surface) of the propagation direction of the light is, the coordinate x is at a transverse coordinates for the light propagation direction is there. In this embodiment, it is assumed that the wave transmission medium is made of a dielectric, and the spatial refractive index distribution is based on the theory described below for the local refractive index of the dielectric constituting the wave transmission medium. This is realized by setting based on this.

  The “field” (input field) formed by the input light 3-1 is modulated according to the spatial distribution of the refractive index of the wave transmission medium constituting the optical circuit, and the “field” formed by the output light 3-2. "(Output field). In other words, the wave transmission medium of the present invention is (electromagnetic) field conversion means for correlating the input field and the output field according to the spatial refractive index distribution. For these input field and output field, the light field in the cross section (cross section along the x axis in the figure) perpendicular to the propagation direction (z axis direction in the figure) in the optical circuit is represented by its location (x, This is called a (forward) propagation image (propagation field or propagation light) in z) (see FIG. 1B).

  Here, “field” generally means an electromagnetic field (electromagnetic field) or a vector potential field of an electromagnetic field. The control of the electromagnetic field in this embodiment corresponds to changing the spatial refractive index distribution provided in the optical circuit, that is, the dielectric constant distribution. Although the dielectric constant is given as a tensor, since the transition between the polarization states is usually not so large, it is an approximation that may be a scalar wave approximation for only one component of the electromagnetic field. Therefore, in this specification, the electromagnetic field is treated as a complex scalar wave. Since the “state” of light includes an energy state (wavelength) and a polarization state, when the “field” is used to express the state of light, the light wavelength and polarization state are also included. Will get.

  In general, in an optical circuit that does not cause amplification or attenuation of propagating light, when the spatial distribution of the refractive index is determined, an image (input field) of the input light 3-1 other than the focal point is an image of the output light 3-2. Uniquely defined for (output field). Such a field of light traveling from the exit surface 2-2 to the entrance surface 2-1 is referred to as a back propagation image (a back propagation field or back propagation light) (see FIG. 1C). Such a back propagation image can be defined for each place in the optical circuit. That is, when a light field at an arbitrary place in the optical circuit is considered, if the place is considered as a virtual “input light” emission point, the image of the output light 3-2 is similar to the above. The back-propagation image at that location can be considered. In this way, a back propagation image can be defined for each location in the optical circuit.

  In particular, in a single optical circuit, when the outgoing field is the propagation field of the incident field, the propagation field and the reverse propagation field coincide with each other at any point of the optical circuit. The field is generally a function over the entire target space, but the term “incident field” or “exit field” means a cross section of the field on the entrance surface or exit surface. In addition, even in the case of “field distribution”, when a discussion is made regarding a specific cross section, it means a cross section of the field with respect to that cross section.

In order to explain the method of determining the refractive index distribution, it is better to use symbols, so the following symbols are used to represent each quantity. Note that the target light (field) is not limited to light in a single state. Therefore, an index j is assigned to light in each state so that light in which a plurality of states are superimposed can be targeted. In general.
Ψ ^j (x): j-th incident field (complex vector value function, defined by intensity distribution and phase distribution set on the incident surface, and wavelength and polarization)
Φ ^j (x): j-th outgoing field (complex vector value function, defined by intensity distribution and phase distribution, wavelength and polarization set on the outgoing face)
Note that ψ ^j (x) and φ ^j (x) have the same total light intensity (or a negligible loss) unless intensity amplification, wavelength conversion, and polarization conversion are performed in the circuit. Their wavelength and polarization are the same.

{Ψ ^j (x), φ ^j (x)}: Input / output pair (a set of input / output fields)
{Ψ ^j (x), φ ^j (x)} is defined by the intensity distribution and the phase distribution, the wavelength and the polarization at the entrance surface and the exit surface.

{N _q }: Refractive index distribution (a set of values for the entire optical circuit design area)
Since one field of light is determined when one refractive index distribution is given to a given incident field and outgoing field, it is necessary to consider a field for the entire refractive index distribution given by the qth iterative operation. Therefore, the entire refractive index distribution may be expressed as n _q (x, z) with (x, z) as an indefinite variable, but the refractive index value n _q (x, z) at the location (x, z) For distinction, {n _q } is used for the entire refractive index distribution.

N _core : A symbol indicating a high refractive index value with respect to the surrounding refractive index, such as a core portion in an optical waveguide.
N _clad : a symbol indicating a low refractive index value with respect to n _core , such as a clad portion in an optical waveguide.
Ψ ^j (z, x, {n _q }): field at location (x, z) when the ^jth incident field ψ ^j (x) is propagated through the refractive index profile {n _q } to z The value of the.
Φ ^j (z, x, {n _q }): at the location (x, z) when the j-th outgoing field φ ^j (x) is propagated back to z in the refractive index profile {n _q } The field value.

In the present embodiment, the refractive index distribution, all j for _{^{ψ j (z e, x,}} {n q}) is given = φ ^j (x), or the so close state {n _q}.

  “Input port” and “output port” are “areas” where the fields at the entrance end face and the exit end face are concentrated. For example, by connecting an optical fiber to the part, the optical intensity can be propagated to the fiber. It is an area. Here, since the field intensity distribution and phase distribution can be designed to be different for the j-th and k-th ones, a plurality of ports can be provided on the entrance end face and the exit end face. Furthermore, when considering a pair of an incident field and an outgoing field, the phase generated by the propagation between them differs depending on the frequency of light. Therefore, for light having different frequencies (that is, light having different wavelengths), the field shape including the phase is included. Regardless of whether they are the same or orthogonal, they can be configured as different ports.

Here, the electromagnetic field is a field of a real vector value, and has a wavelength and a polarization state as parameters, but the value of the component is displayed as a complex number that can be easily handled in a general mathematical manner, and represents the solution of the electromagnetic wave. In the following calculation, it is assumed that the strength of the entire field is normalized to 1. As shown in FIG. 1 (b) and FIG. 1 (c), the propagation field and the back propagation field for the ^jth incident field ψ ^j (x) and output field φ ^j (x) As complex vector value functions, they are expressed as ψ ^j (z, x, {n}) and φ ^j (z, x, {n}). Since the values of these functions vary depending on the refractive index distribution {n}, the refractive index distribution {n} is a parameter. According to the definition of the symbols, ψ ^j (x) = ψ ^j (0, x, {n}) and φ ^j (x) = φ ^j (z _e , x, {n}). The values of these functions can be easily calculated by a known method such as a beam propagation method, given an incident field ψ ^j (x), an outgoing field φ ^j (x), and a refractive index distribution {n}. it can.

In the following, a general algorithm for determining the spatial refractive index distribution will be described. FIG. 2 shows a calculation procedure for determining the spatial refractive index distribution of the wave transmission medium. Since this calculation is repeatedly executed, the number of repetitions is represented by q, and the state of the qth calculation when the calculation is executed up to the (q−1) th is shown. Based on the refractive index distribution {n _q-1 } obtained by the (q-1) th calculation, the propagation field and the ^jth incident field ψ ^j (x) and the outgoing field φ ^j (x) The back propagation field is obtained by numerical calculation, and the results are expressed as ψ ^j (z, x, {n _q-1 }) and φ ^j (z, x, {n _q-1 }), respectively (step S220). ).

Based on these results, the refractive index n _q (z, x) at each location (z, x) is obtained by the following equation (step S240).
n _q (z, x) = n _q-1 (z, x) −αΣ _j Im [φ ^j (z, x, {n _q-1 }) ^* · ψ ^j (z, x, {n _q-1 })] (1)
Here, the symbol “·” in the second term on the right side means an inner product operation, and Im [] means an imaginary number component of the field inner product operation result in []. The symbol “*” is a complex conjugate. The coefficient α is a value obtained by dividing a value equal to or less than a fraction of n _q (z, x) by the number of field pairs, and is a small positive value. Σ _j means that the sum is taken for the index j.

Step S220 and S240 and repeats the value in the exit plane of the propagation field _{^{ψ j (z e, x,}} {n}) the absolute value of the difference between the exit field φ ^j (x) is than desired error d _j When it becomes smaller (step S230: YES), the calculation ends.

In the above calculation, the initial value {n ₀ } of the refractive index distribution may be set appropriately. However, if this initial value {n ₀ } is close to the expected refractive index distribution, the calculation converges faster accordingly ( Step S200). When calculating φ ^j (z, x, {n _q-1 }) and ψ ^j (z, x, {n _q-1 }) for each j, , J (that is, φ ^j (z, x, {n _q-1 }) and ψ ^j (z, x, {n _q-1 })). Thus, calculation efficiency can be improved (step S220). If the computer is configured with a relatively small memory, an appropriate j is selected for each q in the sum of the index j in equation (1), and φ ^j (z, x, { It is also possible to calculate only n _q-1 }) and ψ ^j (z, x, {n _q-1 }) and repeat the subsequent calculations (step S220).

In the above ^{operation, φ j (z, x,} {n q-1}) in the case of values and ^{ψ j (z, x, {} n q-1}) and the value of the near, the formula (1) Im [φ ^j (z, x, {n _q-1 }) ^* · ψ ^j (z, x, {n _q-1 })] is a value corresponding to the phase difference, and by reducing this value, It is possible to obtain a desired output.

The determination of the refractive index distribution can be rephrased as defining a virtual mesh in the wave transmission medium and determining the refractive index of a minute region (pixel) defined by the mesh for each pixel. In principle, such a local refractive index can be an arbitrary (desired) value for each location. The simplest system is a system consisting only of pixels having a low refractive index (n _L ) and pixels having a high refractive index (n _H ), and the overall refractive index distribution due to the spatial distribution of these two types of pixels. Is determined. In this case, the place where the low refractive index pixel exists in the medium is considered as a gap of the high refractive index pixel, and conversely, the place where the high refractive index pixel exists is considered as the gap of the low refractive index pixel. Can do. That is, the wave transmission medium of the present invention can be expressed as a desired place (pixel) in a medium having a uniform refractive index replaced with a pixel having a different refractive index.

  The calculation contents for determining the refractive index distribution described above are summarized as follows. An input port and an output port are provided in a medium capable of transmitting a wave in a holographic manner (dielectric in the case of light). Field distribution 1 (forward propagation light) of propagating light incident from the input port and from the input port A field distribution 2 (reverse propagation light) of phase conjugate light in which an output field expected when an incident optical signal is output from the output port is propagated backward from the output port side is obtained by numerical calculation. In the field distribution 1 and the field distribution 2, a spatial refractive index distribution in the medium is obtained so as to eliminate the phase difference at each point (x, z) of the propagating light and the counter propagating light. If the steepest descent method is adopted as a method for obtaining such a refractive index distribution, the refractive index is calculated by changing the refractive index in the direction obtained by the steepest descent method using the refractive index of each point as a variable. By changing as in (1), the difference between the two fields can be reduced. If such a wave transmission medium is applied to an optical component that emits light incident from an input port to a desired output port, an effective optical path length is reduced due to interference phenomenon caused by multiple scattering of propagation waves generated in the medium. An optical circuit having a sufficiently high optical signal controllability can be configured even with a long and gentle refractive index change (distribution).

  FIG. 3 shows an optical multiplexing / demultiplexing circuit according to an embodiment of the present invention. According to the algorithm described above, a 1 × 2 optical multiplexing / demultiplexing circuit having the refractive index distribution shown in FIG. Here, the black portion in the optical circuit design region 1-1 in the figure is a high refractive index portion (dielectric multiple scattering portion) 1-11 corresponding to the core, and the portion other than the black portion corresponds to the clad. The low refractive index portion 1-12 is a scattering point having a refractive index lower than that of the waveguide. The refractive index of the clad assumes the refractive index of quartz glass, and the refractive index of the core has a value that is higher by 1.5% than the quartz glass. The size of the optical circuit is 300 μm in length and 140 μm in width. The mesh used for the calculation when obtaining the refractive index distribution is 300 × 140.

  FIG. 3B shows a transmission spectrum of the optical multiplexing / demultiplexing circuit. From the transmission spectrum, it can be seen that an optical multiplexer / demultiplexer according to wavelength is formed. However, since the mesh-like wave transmission medium propagates using the effect of interference, the optical path cannot have a large angle, and the crosstalk is large. Therefore, an optical multiplexing / demultiplexing circuit that demultiplexes an optical signal input from the input port into three output ports according to the wavelength will be described in detail as an example.

  FIG. 4 shows a configuration of a wave transmission medium of a three-wavelength optical multiplexing / demultiplexing circuit according to an embodiment of the present invention. When calculation is performed in the same manner as the optical multiplexing / demultiplexing circuit shown in FIG. 3, the size of the optical circuit is 1200 μm in length and 520 μm in width, and the mesh used for the calculation is 1200 × 520. In the optical multiplexing / demultiplexing circuit, the wave transmission medium near the input port 3-1 functions as an input side lens that transmits the optical signal input to the input port 3-1 to the multiplexing / demultiplexing function unit. The wave transmission medium in the vicinity of the output port 3-2 functions as an output side lens for coupling the optical signal demultiplexed for each wavelength in the multiplexing / demultiplexing function unit to each output port 3-2.

  FIG. 5 illustrates a configuration of a three-wavelength optical multiplexing / demultiplexing circuit according to the first embodiment. The three-wavelength optical multiplexing / demultiplexing circuit includes a wave transmission medium 101 that performs multiplexing / demultiplexing of three wavelengths on the substrate 100, and a mirror 102 that optically couples the input port of the substrate 100 and the input port of the wave transmission medium 101. And a mirror 103 that optically couples the output port of the wave transmission medium 101 and the output ports a, b, and c of the substrate 100.

  The mirror 102 corresponds to the input side lens of the wave transmission medium shown in FIG. 4, and the optical signals (wavelength bands λ1, λ2, λ3) input to the input port of the substrate 100 are transmitted to the input port of the wave transmission medium 101. Incident perpendicularly to the end face. The mirror 103 corresponds to the output side lens of the wave transmission medium shown in FIG. 4, and emits an optical signal of each wavelength band emitted from each of the output ports of the wave transmission medium 101 to each output port of the substrate 100. Let The wave transmission medium 101 only needs to have the same function as the multiplexing / demultiplexing function unit of the wave transmission medium shown in FIG. 4, and the size of the optical circuit is 300 μm in length and 300 μm in width. By reducing the circuit length of the wave transmission medium, crosstalk can be reduced.

  The wave transmission medium uses interference, but in a region where the beam diameter of light in the vicinity of the input / output port is small, the proportion of components incident obliquely with respect to the light traveling direction is large. Since the effect of interference varies depending on the angle of incident light, a high proportion of components incident obliquely contributes to the deterioration of crosstalk. As shown in FIG. 5, if the beam diameter of light is expanded using a mirror and then input to the wave transmission medium, the ratio of components incident obliquely decreases, so that crosstalk is improved.

  FIG. 6 illustrates a configuration of a three-wavelength optical multiplexing / demultiplexing circuit according to the second embodiment. The three-wavelength optical multiplexing / demultiplexing circuit is the same as that of the first embodiment, but a plurality of waveguide-type passive elements are further formed on the substrate, and the input / output ports of the substrate 200 and the wave transmission medium 201 are input by different lens functions. The output port is optically coupled. The three-wavelength optical multiplexing / demultiplexing circuit includes a wave transmission medium 201 that performs multiplexing / demultiplexing of three wavelengths on a substrate 200, and a mirror 202 that optically couples the input port of the substrate 200 and the input port of the wave transmission medium 201. The mirror 203 that couples the output port of the wave transmission medium 201 and the output port a of the substrate 200 via the wave transmission medium 205, and the wave that couples the output port of the wave transmission medium 201 and the output port b of the substrate 200. The transmission medium 206 includes a mirror 204 that couples the output port of the wave transmission medium 201 and the output port c of the substrate 200 via a wave transmission medium 207 and a waveguide lens 208.

  The mirror 202 corresponds to the input side lens of the wave transmission medium shown in FIG. 4, and the optical signals (wavelength bands λ1, λ2, λ3) input to the input port of the substrate 200 are input to the input port of the wave transmission medium 201. Incident perpendicularly to the end face. The wave transmission medium 201 has a function equivalent to the multiplexing / demultiplexing function unit of the wave transmission medium shown in FIG. The optical signal in the wavelength band λ 1 is reflected by the mirror 203 and input to the wave transmission medium 205. The wave transmission medium 205 removes excess crosstalk of the optical signal in the wavelength band λ <b> 1 and concentrates it on the output port a of the substrate 200.

  The optical signal in the wavelength band λ <b> 2 is output to the output port b of the substrate 200 after the excess crosstalk is removed by the wave transmission medium 206. The optical signal in the wavelength band λ3 is reflected by the mirror 204 and input to the wave transmission medium 207. The wave transmission medium 207 can scatter optical signals other than the wavelength band λ3, and is effective in improving crosstalk. The optical signal emitted from the wave transmission medium 207 is collected on the output port c of the substrate 200 by the waveguide lens 208.

  In a wave transmission medium, scattered light is generated at an angle substantially close to the light propagation direction. For this reason, if the scattered light is transmitted as it is, it is scattered again by the wave transmission medium, and deterioration due to crosstalk may occur. Since the mirrors 203 and 204 can prevent the scattered light emitted from the wave transmission medium 201 from being emitted to the output port of the substrate 200, crosstalk can be improved.

  FIG. 7 shows a configuration of a three-wavelength optical multiplexing / demultiplexing circuit according to the third embodiment. The three-wavelength optical multiplexing / demultiplexing circuit is the same as that of the first embodiment, except that the microlenses 302 to 305 and the wave transmission medium 301 are directly joined instead of the mirror. By expanding the beam diameter of light using a microlens, the circuit characteristics can be improved as in the first and second embodiments.

It is a figure for demonstrating the basic structure of a wave transmission medium. It is a flowchart which shows the calculation procedure for determining the spatial refractive index distribution of a wave transmission medium. It is a figure which shows the optical multiplexing / demultiplexing circuit concerning one Embodiment of this invention. It is a figure which shows the wave transmission medium of the 3 wavelength optical multiplexing / demultiplexing circuit concerning one Embodiment of this invention. 1 is a diagram illustrating a configuration of a three-wavelength optical multiplexing / demultiplexing circuit according to Example 1. FIG. FIG. 6 is a diagram illustrating a configuration of a three-wavelength optical multiplexing / demultiplexing circuit according to a second embodiment. FIG. 6 is a diagram illustrating a configuration of a three-wavelength optical multiplexing / demultiplexing circuit according to a third embodiment.

Explanation of symbols

1-1 Optical circuit design area 1-2 Substrate 1-1 High refractive index section 1-12 Low refractive index section 2-1 Entrance plane 2-2, 2-3 Exit plane

Claims (4)

In an optical waveguide device composed of a waveguide formed of a cladding layer formed on a substrate and a core portion embedded in the cladding layer,
The core portion includes a pixel shape portion defined by a plurality of scattering points having a refractive index lower than that of the waveguide;
An optical waveguide device comprising: a waveguide passive element that optically couples a port defined in the pixel shape portion and a port of the substrate.   2. The light guide according to claim 1, wherein the waveguide passive element includes a mirror that expands a beam diameter of light at a port of the substrate to obtain a beam diameter of light at the port of the pixel shape portion. Waveguide device.   2. The waveguide passive element includes a waveguide lens that expands a beam diameter of light at a port of the substrate to obtain a beam diameter of light at a port of the pixel shape portion. Optical waveguide device. The waveguide passive element is a pixel shape portion defined by a plurality of scattering points having a refractive index lower than that of the waveguide, and expands a beam diameter of light at a port of the substrate, so that the pixel shape portion The optical waveguide device according to claim 1, wherein the optical waveguide device has a beam diameter of light at the port.

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