JPH11153720A - Wavelength router - Google Patents

Abstract

PROBLEM TO BE SOLVED: To embody the constitution taking the differences in the propagation constants between curvilinear parts and straight parts. SOLUTION: This wavelength router has three input ports 10a to 10c, three input waveguides 12a to 12c of which the respective one-side ends are connected to the corresponding input ports and a first plane waveguide 14 to which the other ends of these input waveguides 12a to 12c are connected. The wavelength router has three output ports 16a to 16c, three output waveguides 18a to 18c of which the respective one-side ends are connected to the corresponding output ports and a second plane waveguide 20 to which the other ends of these output waveguides 18a to 18c are connected. Further, the wavelength router has five connecting waveguides 22a to 22e coupling the output end face 24a of the first plane waveguide and the input end face 26a of the second plane waveguide. When the respective connecting waveguides comprise the straight parts and the curvilinear parts, the curvature of the curvilinear parts and the lengths of the straight parts as well as the straight length from the first connecting part to the first plane waveguide and to the first coupling parts of the respective connecting waveguides are so designed that the phase differences generated by the curvilinear parts are eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength router for separating a wavelength-multiplexed optical signal into different paths for each wavelength.

[0002]

2. Description of the Related Art A conventional configuration of a wavelength router is disclosed in, for example, a document "IEEE. Journal of Selected."
Topics in Quantum Electr
onics Vol. 2 p. 236 1996/6
Month ". The wavelength router disclosed in this document includes two planar waveguides and an array of waveguides coupling between the planar waveguides. This waveguide array is composed of a straight section and a curved section. Then, wavelength separation and wavelength routing are performed using an optical path difference (phase difference) generated between the planar waveguide and the waveguide array due to the wavelength dependency.

[0003]

However, the propagation constant differs between the curved portion and the straight portion constituting the waveguide array. That is, the propagation constant of the waveguide depends on the shape of the waveguide, particularly the curvature. Therefore, unless this effect is taken into consideration, a phase error occurs, and predetermined wavelength separation or wavelength routing is not performed. Until now, no measures have been considered to prevent a phase error caused by this difference in propagation constant.

[0004] Therefore, it has been desired that a wavelength router having a configuration in consideration of a difference in propagation constant between a curved portion and a straight portion is conventionally used.

[0005]

According to the wavelength router of the present invention, there are provided a plurality of input ports for inputting optical signals, a plurality of input waveguides each having one end connected to the corresponding input port, and A first planar waveguide to which the other end of the input waveguide is connected, a plurality of output ports for outputting an optical signal, a plurality of output waveguides each having one end connected to a corresponding output port, and these output waveguides And a plurality of connecting waveguides coupling between an output end face of the first planar waveguide and an input end face of the second planar waveguide. In order to give a phase difference to each other, if the optical path lengths of a plurality of light propagation paths from the first connecting portion of the input waveguide and the first planar waveguide to each of the connecting waveguides and the second coupling portion of the second planar waveguide are different. Waveguide router Are composed of a straight portion and a curved portion, the curvature of the curved portion, the length of the straight portion, and the first planar conductor from the first connection portion are set so as to eliminate the phase error generated in the curved portions. It is characterized in that the waveguide and the linear length reaching the first coupling portion of each connecting waveguide are designed.

As described above, the phase error caused by the difference in the curvature of the curved portion is compensated by appropriate design of the curvature, the length of the straight portion, and the length of the planar waveguide. Therefore,
A phase error caused by a difference in propagation constant between the straight portion and the curved portion of the connecting waveguide can be substantially eliminated. Therefore, it is possible to achieve crosstalk of -25 dB or less, which is necessary when a wavelength router is incorporated in a system and used.

In the wavelength router of the present invention, it is preferable that the output end face has a diffraction grating structure. In the implementation of the wavelength router of the present invention, it is preferable that one end of each of the communication waveguides is respectively coupled to a grating provided in a stepwise shape of the diffraction grating structure.

With this configuration, the length from the first connection portion of the input waveguide and the first planar waveguide to the output end face of the first planar waveguide can be designed to an appropriate value.

In the wavelength router according to the present invention, it is preferable that the output end face and one end of the communication waveguide are connected via a tapered structure. In implementing the wavelength router of the present invention, it is preferable that the tapered structure has a shape that widens from one end of the communication waveguide to the output end face.

With this configuration, the diameter of one end of the connecting waveguide connected to the output end face of the first planar waveguide becomes larger than usual, so that the optical signal propagating in the first planar waveguide is transmitted to each connecting waveguide. The rate of incidence into the inside increases. Therefore, an optical signal can be efficiently condensed in each connecting waveguide. Therefore, even if the optical path length from the first connection part of the input waveguide and the first planar waveguide to the coupling part of the communication waveguide and the first planar waveguide is relatively long, the light amount of the optical signal incident on the communication waveguide Can be suppressed from decreasing.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. It should be noted that the drawings merely schematically show the configuration, size, and positional relationship so that the present invention can be understood. The conditions such as numerical values and materials described below are merely examples. Therefore, the present invention is not limited to this embodiment.

[First Embodiment] The configuration of a wavelength router according to this embodiment will be described. FIG. 1 is a plan view showing a first configuration of the wavelength router. This wavelength router has three input ports 10a, 10b, and 10c, three input waveguides 12a, 12b, and 12c each having one end connected to a corresponding input port, and the other end of these input waveguides connected. And a first planar waveguide 14.
The wavelength router has three output ports 16a and 16b.
16c and three output waveguides 18a, 18b and 18 each having one end connected to a corresponding output port.
c and a second planar waveguide 20 to which the other ends of the output waveguides are connected. In addition, the wavelength router is
Output end face 24a of planar waveguide 14 and second planar waveguide 20
Connecting waveguides 2 coupled to the input end face 26a of the
2a, 22b, 22c, 22d and 22e.

Each of these components is formed on a substrate 28. The substrate 28 is, for example, quartz, an electro-optic crystal, or a semiconductor, and the input waveguides 12 a to 12
c, the first planar waveguide 14, the connecting waveguides 22a to 22e,
A second planar waveguide 20 and output waveguides 18a to 18c are provided. The input waveguides 12a to 12c, the first planar waveguide 14, the connecting waveguides 22a to 22e, the second planar waveguide 20, and the output waveguides 18a to 18c are made of, for example, quartz,
Ferroelectric materials and semiconductors are used. Connecting waveguide 22a
To 22e are arranged at the center of the main surface 28a of the substrate, and the output end face 24a and the input end face 26a of the first and second planar waveguides 14 and 20 are coupled to both ends of each connecting waveguide, and In the figure, these first lines are symmetrical about the center line (II line) of the substrate 28.
And the second planar waveguides 14 and 20 are arranged. Then, the input waveguides 12a to 12c and the output waveguides 18a to 18c are respectively provided between the first planar waveguide 14 and the one substrate end surface 28b and between the second planar waveguide 20 and the other substrate end surface 28c. In the figure, for example, they are arranged so as to be line-symmetric with respect to the center line (II line) of the substrate 28.

Three input ports 10a, 10b and 10c are arranged on one substrate end surface 28b, and the same number of input waveguides 12a, 12b and 12c as the input ports 10a to 10c are provided to form a waveguide array. One end of each input waveguide 12a, 12b and 12c is connected to a corresponding input port 10a, 10b and 10c, respectively;
Further, the other end of each input waveguide is connected to the first planar waveguide 1 respectively.
4 is connected to one end face 24b.

Further, three output ports 16a, 16b and 16c are arranged on the other substrate end face 28c, and the same number of output waveguides 18a, 18a,
8b and 18c are provided to form a waveguide array. One end of each output waveguide 18a, 18b and 18c is connected to the corresponding output port 16a, 16b and 16c, respectively, and the other end of each output waveguide is connected to one end face 26b of the second planar waveguide 20 respectively. .

Also, a plurality of optional and suitable connecting waveguides, here, five connecting waveguides 22a to 22e are provided to form a waveguide array, and one end of each connecting waveguide is connected to the first planar waveguide 1
4 is connected to the other output end face 24a, and the other end of each connecting waveguide is connected to the other input end face 26a of the second planar waveguide 20.

In order to give a phase difference to the optical signal, the first waveguides 14a to 14c and the first planar waveguide 14
From the connection portion, that is, the end face 24b, each connecting waveguide 22a
22e and the second coupling portion of the second planar waveguide 20, that is, the optical path lengths of the plurality of light propagation paths reaching the input end face 26a are designed to be different. Therefore, the input waveguides 12a-
The optical signal that has entered the first planar waveguide 14 from 12c via the end face 24b is diffracted on the end face 24b and diffused in many directions in the first planar waveguide 14. These diffused optical signals reach the multiple positions on the output end face 24a via the respective light propagation paths in the first planar waveguide 14. One end of each of the plurality of communication waveguides 22a to 22e is coupled to a predetermined position of the output end face 24a. Then, through each of the connecting waveguides 22a to 22e, the second
An optical signal is input to the planar waveguide 20. The optical signal reaching the input end face 26a of the second planar waveguide 20 has a different phase state depending on its position. Therefore, at the end face 26b of the second planar waveguide 20, interference occurs between optical signals having different phases. As a result of this interference, wavelength separation is performed, so that an optical signal having a predetermined wavelength is propagated to predetermined output waveguides 18a to 18c.

In the wavelength router of the present invention, the connecting waveguide 2
Each of 2a to 22e is composed of a straight portion and a curved portion.
Then, the curvature of the curved portion, the length of the straight portion, and the first connecting portion (end face 24b) to the first planar waveguide 14 and each of the connecting waveguides 22a to 22e are removed so that the phase error generated in the curved portion is eliminated. First coupling portion 22e (output end face 24a)
And the length of the straight line that leads to.

First, the detailed configuration of the first planar waveguide 14 will be described. FIG. 2 is an enlarged plan view showing the configuration near the first planar waveguide 14. In FIG. 2, only a part of the communication waveguides 22a to 22e is shown, and illustration of the input waveguides 12a to 12c is omitted.

In the configuration example shown in FIG. 2, the first planar waveguide 1
4 are curved such that the output end face 24a and the end face 24b are convex. Then, the first planar waveguide 14
The output end face 24a has a diffraction grating structure. In this configuration example, this diffraction grating structure is formed by providing four grooves extending in a direction perpendicular to the substrate main surface 28a on the output end surface 24a. The output end face 24a is formed with these grooves in such a manner that five gratings are connected in a stepwise manner.

The gratings formed on the connecting waveguides 22a to 22e and the output end face 24a are connected to the connecting waveguides 2a to 22e.
They are arranged so that the extending direction of 2a to 22e is substantially perpendicular to each lattice plane, that is, so that an optical signal is easily introduced into the communication waveguide. Then, the connection waveguides 22a to 22a are connected to the grating provided in the step-like shape of the diffraction grating structure.
One end of each of 2e is connected to each other.

In this embodiment, the output end face 24
A taper 30 is provided for each of the lattices a. The tapered structure of the taper 30 has a shape that diverges from one end of the communication waveguides 22a to 22e to the output end face 24a. That is, the taper 30 is a planar waveguide whose one end is connected to the output end face 24a and whose width becomes smaller as the distance from the connection part increases. One end of each of the communication waveguides 22a to 22e is connected to the other end of each taper 30. As described above, the output end face 24a and the communication waveguides 22a to 22a to
One end of 22e is connected via a tapered structure.
With this configuration, the diameter of one end of each of the communication waveguides 22a to 22e connected to the output end face 24a of the first planar waveguide 14 can be made larger than usual. Therefore, an optical signal propagating through the first planar waveguide 14 is easily introduced into the communication waveguides 22a to 22e.

Next, the output end face of the first planar waveguide 14 is also provided on the input end face 26a of the second planar waveguide 20 provided on the output side so as to be line-symmetric with respect to the II line in FIG. A diffraction grating structure similar to 24a is formed. The second planar waveguide 20 mainly functions as a multiplexing element. A predetermined phase difference is given between the optical signals that have passed through each of the connecting waveguides 22a to 22e and entered the second planar waveguide 20, so that the optical signals interfere with each other, Predetermined output waveguides 18a to 18c
It is distributed to. Further, in this embodiment, since the second planar waveguide 20 is configured as described above, even if an optical signal is input from the output ports 16a to 16c, it functions as a wavelength router.

As described above, each of the connecting waveguides 22
a to 22e are composed of a straight line portion and a curved portion.
For example, as shown in FIG. 2, the connecting waveguide 22d includes a curved portion 22dr having one end coupled to the end surface 24a of the first planar waveguide 14, and a straight portion 22ds coupled to the other end of the curved portion 22dr. It has. The configuration of the connecting waveguide is not limited to the configuration in which one curved portion and one linear portion are connected as described above, but may be a configuration having two curved portions and one linear portion, for example. . Various methods may be used for the connection order of the curved part and the straight part.

FIG. 3 is a plan view showing another structure of the wavelength router. On the substrate 28 constituting the wavelength router, a portion corresponding to the core layer of the waveguide is formed by the material layer 44 having a relatively high refractive index. Further, a portion corresponding to the cladding layer of the waveguide is formed by the material layer 42 having a relatively low refractive index. As shown in FIG. 3, each region of the input waveguide, the output waveguide, and the connection waveguide is defined by the low refractive index material layer 42 formed on the substrate 28. In the figure, the first
Portions of the high refractive index material layer 44 corresponding to the region 46 become the input waveguides 12a to 12c. The portion of the high refractive index material layer 44 corresponding to the second region 48 is the output waveguides 18a to 18a.
8c. The portion of the high refractive index material layer 44 corresponding to the third region 50 becomes the communication waveguides 22a to 22e. Then, the portion of the high refractive index material layer 44 between the first region 46 and the third region 50 becomes the first planar waveguide 14. The high refractive index material layer 44 between the second region 48 and the third region 50
Is the second planar waveguide 20. In this manner, the low refractive index material layer 42 is formed around the high refractive index material layer 44 to utilize the edge propagation mode.

In the third region 50 where the connecting waveguides 22a to 22e are defined, the low refractive index material layer 4 having an arc shape is formed.
2 are arranged in parallel. Both end portions of each low refractive index material layer 42 belonging to the third region 50 (the fourth region 4 in the figure)
1) has a pointed shape. The structure of the taper 30 described above is formed by such a pointed pattern. The taper 30 and the connecting waveguides 22a to 22a-2
At the coupling portion with 2e, the width of the connecting waveguides 22a to 22e is made sufficiently wider than the width of the opening of the taper 30. With this configuration, the equivalent refractive index of the first planar waveguide 14 and the second planar waveguide 20 and the equivalent refractive index of the communication waveguides 22a to 22e can be considered to be the same. That is, the optical path length and the geometric length can be treated the same without considering the refractive index. Therefore, the design of the wavelength router is facilitated.

The materials of the substrate 28, the first planar waveguide 14, the second planar waveguide 20, and the connecting waveguides 22a to 22e are not limited to those described above.
It can also be formed using Si, SiO ₂ , an organic substance, or the like.

Next, an example of the design of the first planar waveguide 14 and the connecting waveguides 22a to 22e constituting the wavelength router will be described with reference to FIG. In this description, a first connection portion between the input waveguide 12b and the end face 24b of the first planar waveguide 14 is defined as an emission point 32 at which an optical signal is emitted into the first planar waveguide 14, and the emission point 32 and the first One-plane waveguide 14
Of the output end face 24a and one end of the communication waveguide 22d.
A straight line connecting the connecting portion is defined as an optical path 34d. A straight line connecting the emission point 32 and the first coupling portion of the first planar waveguide 14 and the connection waveguide 22c is defined as an optical path 34c, and the emission point 3
2 and the first planar waveguide 14 and the first of the connecting waveguide 22e.
A straight line connecting the connecting portion is defined as an optical path 34e. Also, the communication waveguides 22a to 22e are sequentially numbered from No. 1 to No. 5, respectively.

[0029] In FIG. 2, the symbol Lr _i is input waveguide 12b and the first connecting portion the first planar waveguide 14 and the i-th to (emission point 32) of the first planar waveguide 14 (i is an integer (I) shows the i-th optical path length leading to the coupling portion of the connecting waveguide (for the reason described above, the optical path length and the geometric length are treated in the same line). By the symbol △ Lr _i, the difference (Lr _{i + 1}
-Lr _i ). Further, the length of the optical path to a position in the center line I-I in the i-th contact waveguide from the exit point 32 to the optical path length L _i. That is, the difference (L _i -Lr _i)
Is a half of the total length of the i-th connecting waveguide. Then, a straight line J- on the substrate main surface 28a passing through the emission point 32 and perpendicular to the center line of the substrate main surface 28a, that is, the II line.
Set J, the length of the J-J optical path length projected on a line L _i and the projection length Lp. At this time, the difference (L _i -Lp)
Expresses "How much extra road will you go if you make a turn while going straight."
The angle formed by the JJ line and the optical path from the emission point 32 to the first planar waveguide 14 and the first coupling portion of the i-th connecting waveguide is defined as θ _i . Also, the difference (θ _{i + 1} −θ
The _i) represented by the angle △ θ _i.

Further, as described above, each connecting waveguide 2
2a to 22e are composed of a curved part and a straight part. For example, the communication waveguide 22d includes a curved portion 22dr and a straight portion 22ds. Here, the bending radius of the curved portion of the i-th contact waveguide and R _i. FIG.
Exemplifies the case where i = 4. At this time, the center 36 of the curved portion 22dr of the connecting waveguide 22d and the curved portion 22d
The length of the line segment 38 connecting the connection portion of r and the linear portion 22ds bending is equivalent to the radius R _4, also, the line segment 3
The extending direction of 8 is parallel to the extending direction of the II line. A line segment 4 connecting the center 36 of the curved portion 22dr with the first planar waveguide 14 and the first coupling portion of the connecting waveguide 22dr.
The length of 0 is also a radius R ₄ bend. And line segment 3
The angle between 8 and the line segment 40 is θ _i, that is, θ ₄ .

Then, the bending radius R _i and the length Lr _i
And the angle θ _i may be determined. The determination of these values is
This is performed according to the procedure described below.

First, the phase generated from the emission point 32 to the line II in FIG. 2 is expressed by the following equation (1).

[0033]

(Equation 1)

Here, the symbol βp is the first planar waveguide 14
Is shown. The symbol βc indicates the propagation constant of the communication waveguide. The symbol βt indicates the propagation constant of the taper 30. Further, the symbol Lt indicates the length of the taper 30. The symbols βch and Ls _i are the linear portions 22d, respectively.
Represents the propagation constant and length of s. Note that the values of βt and Lt are fixed values. Further, when the curvature R _i of the curved portion constituting the connecting waveguide is small, βc ≒ βc0 + △ βcR _i
It is known that the relationship of ^-2/3 holds. Here, the symbol βc0 is the bias value, and the symbol △ βc is the R of the propagation constant βc.
_This parameter determines _i- dependency.

Next, using the above equation (1), the phase difference △ Φ _i generated between the i-th connecting waveguide and the (i + 1) -th connecting waveguide is expressed by the following equation (2).

[0036]

(Equation 2)

Here, f (R _i ) = βc (R _i ) · R _i
It is. The length Lp is expressed by the following equation (3).

[0038]

(Equation 3)

Therefore, the i-th connecting waveguide and (i + 1)
The difference ΔLp of the length Lp from the second connecting waveguide is represented by the following equation (4).

[0040]

(Equation 4)

Then, in order to connect the connecting waveguides for all i without leaving a gap in the II line, a condition of ΔLp = 0 is necessary. In equation (4), △ Lp
If = 0, the relationship of the following equation (5) is derived. Here, .theta.a _i is the average of the theta _{i + 1} and theta _i.

[0042]

(Equation 5)

By substituting the relationship of equation (5) into equation (2), and for simplicity, when Ls _i = 0,
The curvature difference ΔR _i can be obtained as in the following equation (6).

[0044]

(Equation 6)

Then, as shown in the following equation (7), the length of the i-th connecting waveguide and (i) are given by equations (5) and (6).
+1) th difference △ Lr _i of the length of the contact waveguide is required.

[0046]

(Equation 7)

Here, it is assumed that △ θ _i = △ θ (△ θ is a constant value). Further, there is a relationship of △ Φ _i = △ Φ = mλ ₀ / n. Here, the symbol m represents the diffraction order, the symbol λ ₀ represents the center wavelength, and the symbol n represents the refractive index of the connecting waveguide and the planar waveguide. The element characteristics of the wavelength router are determined by the value of △ Φ, the number of connecting waveguides, and the like.

Therefore, in designing the wavelength router, first, the length Lr ₁ , the curvature R _1, and the angle θ ₁ are set, and the length Lr _{1 is} sequentially determined.
r _{2 to} Lr ₅ , R _{2 to} R ₅ , and θ _{2 to} θ ₅ are calculated. In this _{case, Lr i + 1 = Lr i} + △ Lr i, R i + 1 =
The relationship of R _i + △ R _i and θ _{i + 1} = θ _i + △ θ _i is used. The length Lr ₁ , the curvature R _1, and the angle θ ₁ may be appropriately selected by adding conditions such as minimizing the overall length.

By designing as described above, the curvature of the curved portion and the curvature of the curved portion are reduced so that the phase error generated in the curved portion is eliminated.
The length of the straight portion and the length of the straight line from the first connection portion to the first coupling portion of the first planar waveguide and each connection waveguide can be determined. Therefore, it is possible to prevent a phase error caused by the dependency of the propagation constant βc on R _i . As a result,
Crosstalk of 25 dB or less can be achieved.

[Second Embodiment] Next, a second configuration of the wavelength router will be described. In this wavelength router, a lenticular planar waveguide is provided as a first planar waveguide 14 and a second planar waveguide 20. FIG. 4 is a plan view showing a second configuration of the wavelength router. The first planar waveguide 14 is
It is a biconvex shape having two arcuate curved surfaces 52a and 52b. One curved surface 52a is arranged at a position corresponding to the above-described end surface 24b, and the input waveguides 12a to 12c are coupled to the curved surface 52a.
Further, the other curved surface 52b of the first planar waveguide 14 is the above-described output end surface 24a. The connecting waveguides 22a to 22f are connected to the curved surface 52b.

Similarly, the second planar waveguide 20 is also a biconvex shape having two arcuate curved surfaces 54a and 54b. Output waveguides 16a to 16c are coupled to one curved surface 54a. The connecting waveguide 22 is connected to the other curved surface 54b.
a to 22f are combined.

In such a lens-shaped planar waveguide, the length of the propagation path of each optical signal is constant. Therefore, the optical signals that enter from the coupling portions of the input waveguides 12a to 12c and the first planar waveguide 14 and propagate to the connecting waveguides 22a to 22f respectively travel in the optical paths having the same path length. Therefore, the first planar waveguide 14 and the connecting waveguide 22
At the coupling portions a to 22f, the phase state of each optical signal is the same.

FIG. 5 is an enlarged plan view showing a peripheral portion of the first planar waveguide 14. As shown in FIG. Each of the communication waveguides 22d, 22e, and 22f shown in FIG. 5 includes a straight portion and a curved portion. For example, the connecting waveguide 22f
Is composed of a straight portion 22fs and a curved portion 22fr.

In the second configuration, regardless of the design of the optical path length (indicated by the symbol R in FIG. 5) of each optical signal in the first planar waveguide 14, the linear portions constituting the communication waveguides 22a to 22f are formed. The length is designed to compensate for the phase error. In other words, symbols Lr _i is the length of the straight portion of the contact waveguide in the design procedure described in the first embodiment. If the length Lt of the taper 30 is replaced with (Lt + R), the design can be performed according to the design procedure described in the first embodiment.

[0055]

According to the wavelength router of the present invention, the phase error caused by the difference in the curvature of the curved portion is compensated for by the curvature, the length of the straight portion, and the length of the planar waveguide. Therefore, it is possible to substantially eliminate the phase error caused by the difference in the propagation constant between the straight portion and the curved portion of the connecting waveguide.
Therefore, it is possible to achieve crosstalk of -25 dB or less, which is necessary when a wavelength router is incorporated in a system and used.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a first configuration of a wavelength router.

FIG. 2 is a diagram showing a configuration near a first planar waveguide.

FIG. 3 is a diagram illustrating a structure of a wavelength router.

FIG. 4 is a diagram illustrating a second configuration of the wavelength router.

FIG. 5 is a diagram showing a configuration near a first planar waveguide.

[Explanation of symbols]

 10a to 10c: input port 12a to 12c: input waveguide 14: first planar waveguide 16a to 16c: output port 18a to 18c: output waveguide 20: second planar waveguide 22a to 22e: connecting waveguide 24a: output End surface 26a: Input end surface 24b, 26b, 28b, 28c: End surface 28: Substrate 28a: Main surface 30: Taper 32: Emission point 34c to 34e: Optical path 22dr: Curved portion 22ds: Linear portion 41: Fourth region 42: Low refraction Index material layer 44: high refractive index material layer 46: first area 48: second area 50: third area 52a, 52b, 54a, 54b: curved surface

Claims (5)

[Claims] A plurality of input ports for receiving an optical signal;
A plurality of input waveguides each having one end connected to the corresponding input port, a first planar waveguide connected to the other end of the input waveguide, a plurality of output ports for outputting optical signals, A plurality of output waveguides connected to the corresponding output ports, a second planar waveguide connected to the other end of the output waveguides, an output end face of the first planar waveguide, and the second planar waveguide. A plurality of connecting waveguides for coupling between the input waveguide and an input end face of the waveguide; and providing each of the connecting waveguides from a first connection portion of the input waveguide and the first planar waveguide to provide a phase difference to an optical signal. In a wavelength router having different optical path lengths of a plurality of light propagation paths leading to a waveguide and a second coupling portion of the second planar waveguide, each of the connecting waveguides is constituted by a straight portion and a curved portion. Occurs at these curves when The curvature of the curved portion, the length of the straight portion, and the straight length from the first connection portion to the first coupling portion of the first planar waveguide and each of the connection waveguides so that the phase error is eliminated. A wavelength router characterized by having been designed for: 2. The wavelength router according to claim 1, wherein the output end face has a diffraction grating structure. 3. The wavelength router according to claim 2, wherein one end of each of said connecting waveguides is coupled to a step-like grating of said diffraction grating structure. 4. The wavelength router according to claim 1, wherein the output end face and one end of the communication waveguide are connected via a tapered structure. 5. The wavelength router according to claim 4, wherein the tapered structure has a shape diverging from one end of the connecting waveguide to the output end face.