JP5759430B2 - Wavelength selective switch - Google Patents

Description

  The present invention relates to a wavelength selective switch.

  With the construction of a large-capacity optical communication network that has shown rapid progress in recent years, wavelength division multiplexing (WDM) communication technology has attracted attention and the spread of facilities has progressed, but WDM nodes directly transmit optical signals. In general, a path is switched after being converted into an electric signal once without being controlled. However, in the above method, there is a concern that the processing load at the node is increased, the communication speed is limited, and the power consumption is increased. For this reason, development of a device that performs path switching with an optical signal without going through electrical switching, that is, a wavelength selective switch (WSS) or the like is required.

  The operation principle of a general wavelength selective switch is as follows. The WDM signal input from the input optical fiber propagates through the space as collimated light by the collimator, passes through a plurality of lenses and a diffraction grating for wavelength demultiplexing, and is then condensed again through the lenses. An optical deflecting element for switching the optical signal to a desired output port is disposed at the condensing position. Typical examples of the light deflection element include a micro mirror array, a liquid crystal cell array, a DMD (Digital mirror device), and a LCOS (Liquid crystal on silicon) using a micro-electro mechanical system (MEMS) technology. Each optical signal is reflected at an angle optimized for the output port. Each of the reflected optical signals enters the diffraction grating through the lens, is wavelength-multiplexed, and then couples to the output fiber through the lens.

JP 2009-258438 A

Paul F. McManamon et al., "A Review of Phased Array Steering for Narrow-Band Electrooptical Systems," Proceedings of the IEEE, Vol. 97, No. 6, June 2009, 1078-1096.

  FIG. 1 is a conceptual diagram of a wavelength selective switch having a general configuration, and a more detailed operation of the wavelength selective switch will be described. In the following, in the wavelength selective switch, the direction in which the WDM signal is wavelength-demultiplexed by the diffraction grating is the X axis, the direction orthogonal to the X axis and the direction in which the fibers of the input / output fiber array 101 are arranged are the Y axis, and the optical signal Is defined as the Z axis. For the sake of explanation, the number of the input / output fiber array 101 is set to five, the center fiber is set as the input port, and the fiber arranged at the bottom is set as the output port. Is not limited to this description. The chief ray through which the optical signal emitted from the input fiber passes to the optical deflecting element 107 is represented by a thick solid line, and the optical signal reflected by the optical deflecting element 107 thickens the chief ray to be coupled to the output fiber. It is represented by a broken line.

  The optical signal emitted into the space from the input / output fiber array 101 propagates while spreading at a constant numerical aperture (NA) corresponding to the beam diameter confined by the input / output fiber array 101. The NA of this optical signal is adjusted by the microlens array 102 whose focal length and arrangement position are adjusted so that the optical signal emitted from each optical fiber of the input / output fiber array 101 propagates through the space as collimated light. Further, it is converted into an angle corresponding to the incident position of the condenser lens 103 in the Y-axis direction. This optical signal is converted into an angle again through the lens 104 and then demultiplexed in the X-axis direction by the diffraction grating 105. That is, the optical signal is emitted toward the diffraction grating 105 from a position corresponding to the incident angle at the lens 104 and is demultiplexed by the diffraction grating 105. Further, the optical signal is collected on the light deflection element 107 via the lens 106. In the optical deflection element 107, the optical signal whose angle is adjusted so as to be optimally coupled to the output fiber passes through each lens and the diffraction grating in the reverse direction and reaches the condenser lens 103. The condenser lens 103 has a function of converting to an angle proportional to the height of the beam incident on the condenser lens 103 in the Y-axis direction (the larger the incident position is away from the center in the Y-axis direction, the larger the angle is given and the light is emitted. In addition, the greater the incident angle, the greater the angle of incidence, and the function of functioning to be emitted from a position away from the center in the Y-axis direction. The position and the angle are adjusted so as to be parallel to the Z axis toward the output fiber, and switching can be performed by coupling to a desired output fiber in the input / output fiber array 101. In this operation, since the wavelength of the WDM signal is demultiplexed by the diffraction grating 105, it is possible to distribute each wavelength to a desired output port by setting the optical deflection element 107, and a wavelength-selective switching device. Works as.

  Among such a series of elements, the input / output fiber array 101, the microlens array 102, and the condenser lens 103 have a very small and fine structure, and the manufacturing accuracy and arrangement accuracy of these optical elements are high. A level is required. For example, in the input / output fiber array 101, the state of the fiber end face is directly linked to the disturbance of the beam profile of the output optical signal, and the placement accuracy of each fiber is the crosstalk between ports caused by the coupling of leaked light from adjacent fibers. Directly linked to deterioration. Since the microlens array 102 generally has an extremely short focal length, a lens having a small radius of curvature and a highly accurate manufacturing technique are required. Furthermore, since the alignment of the fiber array 101 and the microlens array 102 is required to have submicron accuracy, in order to construct such an optical system, it is necessary to achieve high manufacturing cost and alignment by using high-precision bulk optical components. Placement technology and mounting load are major problems. Also for the condensing lens 103, a lens having a scale similar to that of the input / output fiber array 101 and the micro lens array 102 is required. There is concern about the load.

  In view of this point, a device has been proposed in which the input / output fiber array 101 and the microlens array 102 are integrated in a silica-based planar lightwave circuit (PLC) to reduce the above-described cost load and work load. (For example, refer to Patent Document 1).

  FIG. 2 shows a schematic configuration diagram of a WSS in which an input / output fiber 101 and a microlens array 102 are integrated in a PLC. In this WSS, the signal light input / output unit is configured as a PLC (optical waveguide substrate 210 in FIG. 2). The optical waveguide substrate 210 includes an input / output waveguide 212, a slab waveguide 214 connected to the input / output waveguide 212, and an arrayed waveguide 216 connected to the slab waveguide 214. The optical path lengths are designed to be equal. In FIG. 2, the direction in which the input / output waveguides 212 are arranged is defined as the X axis, the direction in which the optical signal travels through the optical waveguide substrate 210 is defined as the Z axis, and the direction perpendicular to the X axis and the Z axis is defined as the Y axis. Yes.

  The signal light coupled to the input / output waveguide 212 in the optical waveguide substrate 210 travels while spreading in the slab waveguide 214 in the in-plane direction of the substrate, and recouples to each of the arrayed waveguides 216. Since the optical waveguide length difference of each arrayed waveguide 216 is zero, the light source from the arrayed waveguide 216 is perpendicular to the optical axis at the end portion of the arrayed waveguide 216, that is, the end surface of the optical waveguide substrate 210. When a sufficient number is arranged at regular intervals along the line, the phase of the light emitted from each is equal, and as a result of multi-beam interference, the cylindrical lens 220 causes the optical waveguide base 210 to be in the substrate thickness direction, that is, the Y axis. It is converted into collimated light with respect to direction and propagates through space. Thereafter, the light passes through the beam size conversion unit 240, the spectroscopic unit 250, and the condenser lens 260 and enters the light deflecting unit 270. The signal light is reflected by the optical deflecting unit 270 at an arbitrary angle with respect to a direction perpendicular to the optical waveguide substrate 210, that is, an X-axis direction, with respect to the input / output end surface of the signal light in the optical waveguide substrate 210.

  Here, in Patent Document 1, a lens having power in the X-axis direction is not used among lenses related to light emitted from the optical waveguide substrate 210. Therefore, the optical signal whose reflection angle is controlled so as to be switched to a desired port by the optical deflecting unit 270 is emitted to the optical waveguide substrate 210 in addition to the angle offset by the optical deflecting unit 270 as described above. The position is offset from the time position in the X-axis direction and recombined. The background of adopting such a structure is that the optical design is facilitated by reducing the number of condenser lenses arranged as much as possible, and the cost is reduced by reducing the number of members.

  However, while the configuration of FIG. 2 facilitates spatial optical design, wavefront distortion, aberration, and the like generated by various optical elements cannot all be obtained unless they are compensated in the PLC design. Further, since the position offset in the X-axis direction is generated, the number of the arrayed waveguides 216 of the optical waveguide substrate 210 needs to be arranged in consideration of the offset amount. Since the length in the X-axis direction (the direction perpendicular to the traveling direction of the optical signal in the optical waveguide substrate, also referred to as the width of the optical waveguide substrate in this specification) increases, the optical waveguide substrate 210 is reduced in reducing the device height. There was a problem that the width of the limit was the limiting factor.

  Accordingly, the present invention has been made in view of such problems, and an object of the present invention is to provide an optical waveguide substrate including an input / output waveguide, a slab waveguide, and an arrayed waveguide, and an optical signal in the optical waveguide substrate. As a basic component, at least one condensing lens having power in a direction perpendicular to the traveling direction of the light, a spectroscopic unit, and a light deflecting unit, the position-related offset of light reflected at an arbitrary angle by the light deflecting unit Without incident, recombined into the optical waveguide substrate as incident light with only an angle offset, and output the signal light to any input / output waveguide according to the incident angle to the optical waveguide substrate within the optical waveguide substrate An object of the present invention is to provide a wavelength selective switch capable of satisfying the requirements.

In order to achieve such an object, the present invention provides a wavelength selective switch according to claim 1, wherein the switch is at least one input waveguide, at least one output waveguide, the input waveguide, and the output. An optical waveguide substrate including an slab waveguide connected at the same end as the waveguide, and an arrayed waveguide grating composed of an arrayed waveguide connected to the slab waveguide, and wavelength multiplexed light emitted from the arrayed waveguide Spectroscopic means for wavelength-separating signals, a lens, and a phase shift to the wavelength-separated optical signal collected by the lens independently, and the optical signal to which the phase shift is applied is the lens and the spectral means via a light deflection means for reflecting to recombine the arrayed waveguide, the optical signal from each of said input waveguide and the output waveguide to the slab waveguide When force, each of the principal rays of the signal light propagates through the same waveguide in the intersection the arrayed waveguide at a point of the arrayed waveguide is connected to the side end of the slab waveguide It is produced so that it may output from the same position in an optical waveguide board | substrate.

The invention according to claim 2 is the wavelength selective switch according to claim 1, wherein the array waveguide has an interval on the slab waveguide side smaller than an interval on the spectroscopic means side, and the array waveguide. Using the incident angle θ ₁ of the optical signal incident on the waveguide from the optical deflection means side, the refractive index n _{air of air} , the pitch d ₁ of the arrayed waveguide on the end face of the optical waveguide substrate, and the wavelength λ of the signal light , Characterized by satisfying the following formula.

The invention according to claim 3 is the wavelength selective switch according to claim 1 or 2, wherein two adjacent ones of the input waveguide and the output waveguide are provided at the terminal portion of the slab waveguide . The interval is not constant .

  As described above, according to the present invention, since there is no position offset in the direction perpendicular to the traveling direction of the optical signal in the optical waveguide substrate, it is possible to reduce the height and simplify the design policy of the PLC. Thus, the layout can be easily realized.

It is a conceptual diagram of a wavelength selective switch having a general configuration. It is a schematic block diagram of the wavelength selective switch which integrated the input-output fiber and the micro lens array in PLC, (a) is a top view, (b) is a side view. It is a block diagram of the wavelength selective switch concerning one Embodiment of this invention, (a) is a top view, (b) is a side view. It is a figure for demonstrating the optical waveguide board | substrate of the wavelength selective switch concerning one Embodiment of this invention. It is a figure which shows the characteristic of the optical waveguide board | substrate of the wavelength selective switch concerning one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the embodiments. Note that the same reference numerals denote the same or corresponding parts throughout the drawings.

  FIG. 3 is a diagram showing the configuration of an embodiment of a wavelength selective switch according to the present invention. FIG. 3A is a top view, and FIG. 3B is a side view.

  As shown in FIG. 3, the wavelength selective switch according to the present embodiment includes an optical waveguide substrate 301, a cylindrical lens 302, a lens 303, a diffraction grating 304, a lens 305, and an optical deflection element 306. In the description of the present embodiment, the substrate thickness direction of the optical waveguide substrate 301 is the X axis, and the optical axis direction of the signal light emitted from the optical waveguide substrate 301 is the Z axis, the direction perpendicular to the X axis and the Z axis ( The Y-axis is defined as the direction perpendicular to the traveling direction of the signal light in the optical waveguide substrate. In FIG. 3, the principal ray of the signal light transmitted through the diffraction grating 304 for wavelength demultiplexing usually undergoes an angle conversion of about 90 ° in the XZ plane by diffraction, but will be described in this specification. In order to simplify the explanation, the optical axis direction of the signal light will always be described as the Z axis.

  The cylindrical lens 302 has power with respect to the X axis and acts on the signal light in the X axis direction, but does not act on the Y axis. The cylindrical lens 302 acts so that the signal light emitted from the optical waveguide substrate 301 does not spread in the X-axis direction.

  The lens 303 has power relating to both the X-axis and the Y-axis, and acts to convert the lens action, that is, the angle and position of the signal light, with respect to both axes. The lens 303 acts so that the signal light incident on the lens 303 with a larger incident angle is emitted from a position farther from the center position with respect to the signal light transmitted through the cylindrical lens 302. Further, the lens 303 acts so that the signal light that has entered the position further away from the center position is emitted at a larger emission angle with respect to the signal light transmitted through the diffraction grating 304.

  The diffraction grating 304 acts to demultiplex the signal light transmitted through the lens 303 for each wavelength. The wavelength dispersion axis by the diffraction grating 304 coincides with the X-axis direction. The signal light that has passed through the diffraction grating 304 passes through the lens 305 and is condensed on the light deflection element 306 for each wavelength.

  Similarly to the lens 303, the lens 305 has power on both the X axis and the Y axis. The lens 305 acts so that the signal light transmitted through the diffraction grating 304 is emitted at an angle corresponding to the incident position and condensed on the optical polarizer 306. The lens 305 acts so that the signal light reflected by the optical polarizer is emitted from the emission position corresponding to the incident angle toward the diffraction grating 304.

  The optical deflecting element 306 acts to reflect the optical signal of each wavelength at an angle that optimally couples to a desired output port. The light deflection element 306 can be a micromirror array, a liquid crystal cell array, DMD, LCOS, or the like based on MEMS technology, and reflects signal light of each wavelength at an angle optimized for a target output port.

  In the description of the present embodiment, the cylindrical lens 302 and the lenses 303 and 305 are used in this order as the lens system. However, any number of lenses may be used as long as they have the same optical characteristics. There is no problem with any arrangement. Further, when the diffraction grating 304 has a configuration in which the optical paths of incident light and diffracted light are relatively close to each other, the lens 303 and the lens 305 can be the same lens.

  FIG. 4 shows details of the optical waveguide substrate 301. As shown in FIG. 4, the optical waveguide substrate 301 includes an input waveguide 401, at least one output waveguide 402, a slab waveguide 403 to which the input waveguide 401 and the output waveguide 402 are connected, and a slab waveguide. And an arrayed waveguide 404 connected to 403.

  In this embodiment, the number of input waveguides 401 is one and the number of output waveguides 402 is N (N is an integer). However, from the principle of reciprocity of light, the number of input waveguides 401 is N. There is no problem even if a wavelength selective switch is used with a configuration in which the number of the output waveguides 402 is one. It should be noted that the difference between the input waveguide and the output waveguide does not physically exist, and is only a difference in setting which waveguide from which light is incident and from which waveguide is output.

  With respect to the input waveguide 401 and the output waveguide 402, signal light is emitted from the respective waveguides so that the principal ray when propagating through the slab waveguide 403 intersects at a certain point at the end of the slab waveguide 403. In addition, the installation angles of the input waveguide 401 and the output waveguide 402 are determined. This is because the principal ray of signal light incident on the slab waveguide 403 from an arbitrary output waveguide and the principal ray of signal light incident on the slab waveguide 403 from the input waveguide are the end points of the slab waveguide 403. Are propagated through the same waveguide in the arrayed waveguide 404 at one point and output from the same position in the optical waveguide substrate 301, or straight lines extended from each of the input waveguide and the output waveguide are slab waveguides. An input waveguide and an output waveguide are produced so that they intersect at one point on the opposite end face of 403 and propagate through the same waveguide in the arrayed waveguide 404 and output from the same position on the optical waveguide substrate 301. It means that With this structure, light from all angles is superimposed on the output end of the optical waveguide substrate 301, and no offset of the position in the Y-axis direction occurs, so that the optical waveguide substrate 301 can be miniaturized.

The operation of the wavelength selective switch of the present invention is as follows. First, signal light (wavelength multiplexed optical signal) input to the input waveguide 401 propagates in the slab waveguide 403 so as to spread in the plane of the optical waveguide substrate 301 while being confined in the X-axis direction. To do. Since the wavefront of the spreading signal light has a curvature corresponding to the propagation distance, the end of the slab waveguide 403 is configured to match the curvature of the wavefront. An arrayed waveguide 404 having the same length is connected to the end of the slab waveguide 403. Here, among the end faces of the optical waveguide substrate 301, the end face to which the arrayed waveguide 404 is connected coincides with the Y axis. In this configuration, the optical signal output to the space from the arrayed waveguide 404 is output as a plane wave whose phase is aligned in the Y-axis direction, and therefore propagates in the space as a collimated beam in the Y-axis direction. Here, since the beam output to this space behaves as divergent light having a large NA in the substrate thickness direction of the optical waveguide substrate 301, that is, in the X-axis direction, the beam is collimated by the cylindrical lens 302 so as to be collimated in the X-axis direction. It is desirable to suppress the divergence. The optical signal that has passed through the cylindrical lens 302 passes through the lens 303 and is collected on the diffraction grating 304. Each signal light that has been angle-demultiplexed for each wavelength by the diffraction grating 304 further passes through the lens 305, undergoes angular position conversion for each wavelength, and enters the light deflecting element 306 perpendicularly to deflect light. The light is condensed on the element 306. The signal light is reflected at an arbitrary angle by the light deflecting element 306 for each wavelength, and is recombined with the optical waveguide substrate 301 via the lens 305, the diffraction grating 304, the lens 303, and the cylindrical lens 302 again. Here, an angle formed between the principal ray of the signal light emitted from the input port and guided through the slab waveguide 403 and the principal ray when the reflected light deflected by the light deflecting element 306 enters the optical waveguide substrate 301 is defined. θ ₁ , the pitch of the arrayed waveguide 404 at the end face of the optical waveguide substrate 301 is d ₁ , the pitch of the arrayed waveguide 404 connected to the slab waveguide 403 is d ₂ , the length of the slab waveguide 403 is f _slab , and the input guide When the distance from the connection point between the waveguide 401 and the slab waveguide 403 to the connection point between the output waveguide 402 and the slab waveguide 403 is d ₃ and the refractive index of the slab waveguide 403 is n _s , 2, the principal ray of the signal light emitted from the input port (input waveguide 401) and the reflected light deflected by the light deflection element 306 enter the optical waveguide substrate 301. The angle formed by the principal ray at the time of θ ₂ can be expressed as in the following formula 1.

As is clear from Equation 1, the light recombined with the optical waveguide substrate 301 at the angle θ ₁ is separated from the connection point between the input waveguide 401 and the slab waveguide 403 by a distance d ₃ and has an angle θ _2. In addition, since only the output waveguide 402 connected to the slab waveguide 403 is guided, a switching operation is possible.

Also, from Equation 1, θ ₂ can be enhanced according to the ratio of the pitch d ₁ of the arrayed waveguide 404 on the end face of the optical waveguide substrate 301 and the pitch d ₂ of the arrayed waveguide 404 connected to the slab waveguide 403. I understand. That is, even small angle theta ₂ which is deflected by the light deflector 306, can have a large angular change in the slab waveguide 403, the improvement of the output ports can be achieved. However, although the angle enhancement effect is produced by designing the pitch d ₁ to be wide and the pitch d ₂ to be narrow, the problem of FSR (free spectral range) depending on the pitch d ₁ appears. The interference condition of light from each waveguide at the end of the arrayed waveguide 404 can be expressed by the following formula 2.

In the equation, n _air represents the refractive index of air, m represents the diffraction order, and λ represents the wavelength of the signal light. When the wavelength λ = 1.59 μm, the refractive index n _air = 1, and the pitch d ₁ = 10 μm, the maximum θ ₁ that can be taken when the order m = ₁ , that is, the FSR is calculated as 9.149 deg (± 4.574 deg). Is done. Therefore, even if θ ₁ larger than this is set, higher-order diffraction will occur, and it is clear that the signal light is not coupled to the desired output waveguide. Therefore, when using the angle enhancement configuration of the previous operation, it is desirable to set θ ₁ so as to satisfy the following expression 3 with the order m = 1 in expression 2.

The emission angle of the precision formed on the optical waveguide substrate 301, shows a theta ₁ characteristic example of theta ₁ and measurements designed to FIG. In this characteristic example, the total number of input waveguides and output waveguides is 10, the number 9 waveguide is set as the input waveguide, and the other 9 are assigned to the output waveguide. Based on the output angle from the input waveguide at this time, the measured value of the angle coupled to the angular output waveguide is indicated by the black solid line, the design value is indicated by the gray broken line, and the difference between the two is indicated by the black broken line. ing. In this characteristic example, by adjusting the PLC layout, an extremely high-precision optical characteristic with an error within 0.005 deg for all ports is realized without alignment. In order to realize the same characteristics with the combination of the input / output fiber array 101, the microlens array 102, and the condenser lens 103 as shown in FIG. 1, an alignment adjustment mechanism of μm order is provided for each, and a high optical element is produced. Technology will be required, and realization is not easy.

  In general, the input / output fiber array 101 manufactured by a normal process takes a structure in which the distance between adjacent ports is constant. This is because it is technically difficult to manufacture the input / output fiber array 101 and the microlens array 102 having irregular distances between ports. However, in reality, this inter-port distance is a dummy installed to avoid unnecessary high-order diffracted light generated by the optical deflecting element 306 and to give arbitrary intensity attenuation so that the signal intensity from each output waveguide becomes constant. In many cases, an irregular port arrangement is desired in consideration of the arrangement of the output waveguide and the like.

  For example, Non-Patent Document 1 describes the above-described phenomenon that requires irregular port arrangement. As a device actually considered as the light deflection element 306, a MEMS mirror array, a liquid crystal cell, or the like has been often used. In recent years, it is compatible with flexible grid technology that has been studied from the viewpoint of effective use of frequency resources, and an element called LCOS has attracted attention as the most promising optical deflection element because of the advantage that any phase change can be freely set. Collecting. LCOS is a phase modulation cell array based on liquid crystal, which is composed of a group of finely arranged pixels. An optical signal can be deflected by performing a linear function phase modulation using a point that an independent phase modulation amount can be freely set for each pixel. It should be noted here that liquid crystal is used as the LCOS phase modulation means, so that a too large phase modulation amount cannot be set, and the upper limit is generally set to about 2π. Due to this limitation, when LCOS is used as an optical deflection element, FIG. In general, the phase is set to be turned back every 2π as shown in FIG. 1, and the adjustment is performed so that the phase gradient when viewed macroscopically becomes a desired one.

  Here, when 2π folding phase setting is performed using LCOS, FIG. As described in FIG. 8, a gentle phase modulation region is generated so as to smooth and connect pixels having adjacent phases. This is a phenomenon that occurs when an electric field generated at an electrode arranged in each pixel brings an interaction to an adjacent electrode. This interaction causes a component that diffracts light in a direction other than the originally intended deflection direction, that is, causes high-order diffracted light. It is necessary to prevent the high-order diffracted light from being coupled to other than the output port from which the optical signal should be emitted, that is, the deterioration of crosstalk between the ports. For this reason, in order to prevent interference from unnecessary high-order diffracted light, it is also effective to perform an irregular port arrangement without keeping the inter-port distance constant.

  In the combination of the fiber array 101 and the microlens array 102 described above, it is difficult to cope with a complicated structure that is nonlinear with respect to an angular difference between adjacent ports. In this respect, this characteristic example also has an advantage that even a very complicated structure can be realized without requiring any additional member by only changing the parameters of the output waveguide 402 when designing the optical waveguide substrate. Yes.

  The switching operation in the wavelength selective switch according to the present embodiment is such that the light deflecting element 306 is focused on the light deflecting element 306 by the diffraction grating 304 and the lens 305 at different positions. A structure capable of reflecting signal light at a desired deflection angle enables wavelength-selective port switching. Typical examples of the optical deflecting element 306 that realizes such a function include a micromirror array, a liquid crystal cell array, DMD, and LCOS based on MEMS technology. In particular, in the MEMS array, since the deflection angle can be increased, an increase in the number of output ports can be expected. In addition, when a deflection element such as LCOS or DMD in which a large number of fine pixels are two-dimensionally arranged is used, the wavelength interval can be freely adjusted only by setting deflection of the element. The utilization efficiency can be improved.

  Usually, since the wavelength selective switch is used upright in the device, it is a problem to reduce the width of the optical waveguide substrate 210 in the Y-axis direction (reducing the height of the device). According to the wavelength selective switch of the present embodiment, the width in the Y-axis direction can be suppressed as described above, and the device can be reduced in height.

DESCRIPTION OF SYMBOLS 301 Optical waveguide board | substrate 302 Cylindrical lens 303,305 Lens 304 Diffraction grating 306 Optical deflection element 401 Input waveguide 402 Output waveguide 403 Slab waveguide 404 Array waveguide

Claims (3)

An array comprising at least one input waveguide, at least one output waveguide, a slab waveguide connected at the same end as the input waveguide and the output waveguide, and an array waveguide connected to the slab waveguide An optical waveguide substrate including a waveguide grating;
Spectroscopic means for wavelength-separating the wavelength multiplexed optical signal emitted from the arrayed waveguide;
A lens,
A phase shift is independently applied to the wavelength-separated optical signal collected by the lens, and the optical signal to which the phase shift is applied is recombined with the arrayed waveguide through the lens and the spectroscopic means. And light deflecting means for reflecting
When the signal light from each of said input waveguide and the output waveguide and input to the slab waveguide, each of the principal ray of the signal light of the arrayed waveguide is connected side of the slab waveguide wavelength selective switch characterized in that it is produced as output from the same position by propagating the same waveguide in communion the arrayed waveguide at a point of termination of the optical waveguide substrate. The arrayed waveguide is
An interval on the slab waveguide side is smaller than an interval on the spectroscopic means side, and an incident angle θ ₁ of an optical signal incident on the arrayed waveguide from the optical deflection means side, an air refractive index n _air , the optical waveguide 2. The wavelength selective switch according to claim 1, wherein the following expression is satisfied using the pitch d ₁ of the arrayed waveguides on the end face of the substrate and the wavelength λ of the signal light.

3. The wavelength selective switch according to claim 1, wherein, in the terminal portion of the slab waveguide, a distance between two adjacent ones of the input waveguide and the output waveguide is not constant .

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