JP2012220924A - N×n wavelength selection switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an N×N wavelength selection switch capable of simultaneously executing DEMUX operation and MUX operation of two or more light beams of the same wavelength by a simple unit.SOLUTION: An N×N wavelength selection switch 20 includes an input side waveguide type branch circuit 7a and an output side waveguide type branch circuit 7b of a port number N, is for, when multiwavelength light of a wavelength number M is inputted to one input port of the input side waveguide type branch circuit 7a, outputting the multiwavelength light from an optional output port of the output side waveguide type branch circuit 7b for each wavelength, and comprises spectroscopic means, an input side two-dimensional MEMS mirror 16a including mirrors that are arranged in N columns and arrayed in M rows and selectively reflect each single wavelength light in an optional direction, reflection means, an output side two-dimensional MEMS mirror 16b including mirrors that are arranged in N columns and arrayed in M rows and reflect each single wavelength light to a specific direction, and condensing means.

Description

  The present invention relates to an N × N wavelength selective switch.

  FIG. 9 is a diagram illustrating a configuration example of a certain node device 91 in the mesh network 90.

  As shown in FIG. 9, generally, in an optical network, the optical fiber is duplexed by a pair of optical fibers 92 so that the optical communication is not interrupted even if the optical fiber is disconnected or the transmission apparatus fails.

  For example, in a method called 1 + 1 protection, one optical fiber 92a of the pair optical fiber 92 is simultaneously transmitted from West to East, and the other optical fiber 92b is simultaneously transmitted from East to West, and the main optical fiber 92a (West → East) is transmitted. In the case of disconnection, the failure is avoided by switching to the other optical fiber 92b (East → West) instantly.

  The node device 91 has a configuration having paired optical fibers 92, 93, 94 in three directions (referred to as 3Degree), that is, the paired optical fibers 92, 92 toward three nodes located in the West, East, and North directions. 93 and 94 are laid.

  Hereinafter, the operation of the node device 91 will be described.

  The node device 91 is composed of network interfaces (NW interfaces A, B, and C). Now, pay attention to the NW interface A.

  A wavelength signal of about 100 waves is multiplexed on the optical fiber 92a, which is one of the pair optical fibers 92 transmitted from West to East, and after being branched into four by the 1 × 4 optical splitter 95, Each of the two signals enters two TX / RX banks I and II, and is multiplexed (MUX) into one by a wavelength selective switch (WSS) 96. After entering the wavelength selective switch 97 and demultiplexing (DEMUX), it is received by the wavelength variable receiver (λ-RX) 98.

  Here, the reason why the configuration includes two TX / RX banks I and II is that even if one TX / RX bank I (or II) fails, another TX / RX bank II (or I) ) To avoid system down.

  The reason why the complicated configuration in which the two wavelength selective switches 96 and 97 are arranged to face each other is because there is no multi-input, multi-output N × N wavelength selective switch at present.

  On the other hand, the remaining two optical signals after being branched into four by the 1 × 4 optical splitter 95 are connected to the 1 × 4 wavelength selective switch 99 of the NW interfaces B and C, respectively, and are nodes located in the East and North directions. Is transmitted toward.

  On the other hand, the 1 × 4 wavelength selective switch 99 in the NW interface A has an optical signal from the 1 × 4 optical splitter 95 in the NW interfaces B and C and a wavelength variable transmitter in the two TX / RX banks I and II ( The optical signal from (λ−TX) 100 is input. The light from the wavelength tunable transmitter 100 in the TX / RX banks I and II passes through the two optical splitters 101 and 102 arranged to face each other.

  The reason why each NW interface A, B, C is distributed using the 1 × 4 optical splitter 95 is that multiplexed optical signals coming from a certain direction (for example, West) are added to the Add port 103 and Drop port 104 ( Distribution to all NW interfaces A, B, and C including ports to TX / RX banks I and II), and using the wavelength selective switch 99, the optical signal is selected and the power is adjusted. Build an optical network that broadcasts part of the wavelength signal and distributes it to all NW interfaces A, B, and C, or selects part of the wavelength signal and routes to only one NW interface A, B, and C This is because it can.

  In this case, each optical fiber is monitored and controlled by the network management layer so that two or more optical signals of the same wavelength (different information are transmitted) are not transmitted simultaneously.

  This wavelength selective switch 99 also has a function of connecting an arbitrary number of arbitrary wavelength signals to an arbitrary port and a variable attenuation function of each optical signal. However, it is necessary to increase the number N of 1 × N wavelength selective switches as the number of node degrees increases.

  The 1 × N wavelength selective switch (N = 2, 3,...) Will be described below.

  FIG. 10 is a diagram showing a conventional 1 × N wavelength selective switch (see Non-Patent Document 1).

  As shown in FIG. 10, this 1 × N wavelength selective switch 110 includes an input / output optical fiber 111, a collimating lens array 112, and characteristics between horizontal polarization (Y polarization) and vertical polarization (X polarization). , A half-wave plate 114 that rotates one of its horizontally polarized waves and vertically polarized waves by 90 degrees, and anamorphic that spatially converts a circular distribution of light into an elliptic distribution A prism pair 115, a condenser lens 116, a MEMS (Micro Electro Mechanical System) micromirror array 117, a resolution lens 118, and a bulk type grating 119 are included.

  FIG. 11 is a diagram showing another conventional 1 × N wavelength selective switch (see Patent Document 1).

  As shown in FIG. 11, the 1 × N wavelength selective switch 600 includes input / output optical fibers 601 to 606, a collimator lens array 610, and between horizontal polarization (Y polarization) and vertical polarization (X polarization). A Wollaston prism 615 (consisting of two triangular prisms 616 and 617) and a compound for making the phase difference between the horizontal polarization and the vertical polarization zero. A refractive index plate 620, a half-wave plate 625 (only 626 is a half-wave plate and 627 does not affect polarization), a concave mirror 630, a cylindrical lens 635, and a grating 642 with an edge prism 641 , A prism 646 for bending light vertically, and LCOS SLM (Liquid Crystal On Silicon Spatial Light Mo duplicator) 645.

  These conventional 1 × N wavelength selective switches 110 and 600 basically have the following functions, although their configurations are different.

  (1) The input / output port configuration is 1 × N (N = 2, 3, 4,...).

(2) DEMUX function switching: When an optical signal with a multiplexed wavelength is incident on one input port, an arbitrary wavelength (for example, λ ₁ , λ ₅ , λ ₂₉ ), an arbitrary wavelength is selected from the input optical signals. A number (for example, three wavelengths in the case of λ ₁ , λ ₅ , and λ ₂₉ ) can be output to an arbitrary output port (a port among N ports), and the state can be changed (switched).

  (3) MUX function: Conversely, an arbitrary wavelength incident from an arbitrary port among N ports can be multiplexed to one output port. However, light of the same wavelength incident from two of the N ports is selected and output to one output port.

  (4) Variable attenuation function: In the MUX / DEMUX, the optical signal power of each wavelength can be adjusted to a desired value.

US Patent Application Publication No. 2006/67611

Journal of Lightwave Technology, VOL. 23, NO. 4, APRIL. 2005

  The above-mentioned wavelength selective switch is limited because the input / output port configuration is 1 × N (N = 2, 3, 4,...), So two or more of the same wavelengths having different information are used. This is the point that the DEMUX operation and the MUX operation cannot be performed simultaneously with light.

  This is extremely disadvantageous in realizing the current optical network function shown in FIG. 9, and will be described in detail below.

In the current optical network shown in FIG. 9, light (for example, λ _{1 to} λ ₁₀₀ ) multiplexed on one optical fiber is independently transmitted. For this reason, it is necessary to switch optical signals of various wavelengths between arbitrary optical fibers under the restriction that two or more optical signals having the same wavelength are not simultaneously incident on one optical fiber. However, since the 1 × N wavelength selective switch alone cannot simultaneously perform two or more lights having the same wavelength in the DEMUX operation and the MUX operation, it is realized by the following configuration.

  After being equally distributed to the four wavelength groups by the optical splitter, it is connected to the 1 × N wavelength selective switch of each NW interface. At this time, the same wavelength including two or more different pieces of information is incident on the 1 × N wavelength selective switch. Thereafter, an optical signal having an unnecessary wavelength is selected by a wavelength selective switch so that light having the same wavelength does not collide, and only a desired optical signal is transmitted. These controls are performed by remotely controlling the switching state of the 1 × N wavelength selective switch at the network management layer. Similarly, in the drop port in the TX / RX bank, signals of the same wavelength (information is different) dropped from each NW interface are sent to the wavelength variable receiver (λ-RX) without colliding with each other. X N wavelength selective switches are connected to face each other. Further, in the Add port in the TX / RX bank, 1 × N splitters are connected to face each other, and signals from a large number of wavelength variable transmitters (λ-TX) are sent to each NW interface.

  However, in order to realize the above function, in FIG. 9, seven wavelength selective switches and seven optical splitters are used, which is extremely expensive. The optical splitter only distributes the optical power. For example, since the loss of a 1 × 4 optical splitter is about 6 dB per unit, the loss is large as a whole, and an expensive optical amplifier is required to compensate for this. As described above, the current optical network using the 1 × N wavelength selective switch has a very inefficient system form. This cause is derived from the function of the 1 × N wavelength selective switch that constructs the system.

  Accordingly, an object of the present invention is to provide an N × N wavelength selective switch capable of solving the above-described problems and capable of simultaneously performing DEMUX operation and MUX operation of two or more lights having the same wavelength alone. .

  The present invention devised to achieve this object includes an input-side waveguide branch circuit having N ports (N is an integer of 2 or more) having a plurality of input ports arranged in parallel in the planar direction, and the planar direction. A number N of output-side waveguide branch circuits having a plurality of output ports arranged in parallel with each other, and the number of wavelengths M (M is an integer of 2 or more) at one input port of the input-side waveguide branch circuit ) N × N wavelength selective switch for outputting the multi-wavelength light from any output port of the output-side waveguide branch circuit for each wavelength when the multi-wavelength light is input. Spectroscopic means for dispersing multi-wavelength light from the waveguide type branch circuit for each wavelength in a direction orthogonal to the plane direction, and N in the plane direction corresponding to each input port of the input side waveguide type branch circuit. Each array arranged and spectrally separated by the spectroscopic means An input-side two-dimensional MEMS mirror having a mirror corresponding to wavelength light and arranged in M rows in a direction orthogonal to the planar direction and selectively reflecting each single wavelength light in the planar direction in an arbitrary direction of the planar direction Reflecting means for reflecting each single-wavelength light reflected by the input-side two-dimensional MEMS mirror, N rows arranged in the plane direction corresponding to each port of the output-side waveguide branch circuit, and A mirror that is arranged in M rows in a direction orthogonal to the planar direction corresponding to each single wavelength light reflected by the reflecting means, and reflects each single wavelength light from the reflecting means toward a specific direction in the planar direction. Output-side two-dimensional MEMS mirror, and each single-wavelength light from the output-side two-dimensional MEMS mirror is combined with each single-wavelength light in a direction orthogonal to the plane direction, and the output-side waveguide branch circuit Any output port And an N × N wavelength selective switch provided with a condensing unit that outputs the light.

  In the present invention, the number N of ports in which a plurality of waveguides as input ports to which multi-wavelength light having a wavelength number M (M is an integer of 2 or more) is input is arranged in parallel in a plane direction (N is 2 or more). Integer) input waveguide, and an input-side waveguide branch circuit having an input-side slab waveguide that spreads multi-wavelength light input to the input waveguide in the planar direction, and the input-side waveguide-type branch circuit The input side first lens that collimates the multi-wavelength light spread in the plane direction, and the input side first lens that collimates the multi-wavelength light collimated by the input side first lens in a direction orthogonal to the plane direction. Two lenses, an input-side third lens that condenses multi-wavelength light collimated by the input-side second lens in the plane direction, and multi-wavelength light condensed by the input-side third lens, Spectroscopy for each wavelength in a direction perpendicular to the plane direction An input-side grating, an input-side fourth lens that collimates each single-wavelength light split by the input-side grating in a direction perpendicular to the plane direction, and N rows of mirrors in the plane direction, and the plane direction Each of the single-wavelength light collimated by the input-side fourth lens and reflected by the M-row mirror for each wavelength and collimated by the input-side fourth lens. An input-side two-dimensional MEMS mirror that converts the traveling angle of single-wavelength light for each port using an N-row mirror, and each angle that is reflected for each wavelength by the input-side two-dimensional MEMS mirror and converted for each port. A reflecting lens that condenses the single wavelength light in the plane direction, a reflecting member that reflects the single wavelength light collected by the reflecting lens to the reflecting lens again, and the planar direction Each having N rows of mirrors and M rows of mirrors in a direction perpendicular to the plane direction, and each single-wavelength light reflected by the reflecting member and passing through the reflecting lens again is converted into wavelengths by the M rows of mirrors. The output side two-dimensional MEMS mirror that reflects each time and converts the traveling angle of each single-wavelength light for each port by an N-row mirror, and is reflected by the output side two-dimensional MEMS mirror for each wavelength and proceeds for each port. An output-side fourth lens that collects each single-wavelength light whose angle has been converted in a direction orthogonal to the plane direction, and each single-wavelength light that is collected by the output-side fourth lens is the plane direction. An output side grating that is multiplexed for each port in a direction orthogonal to each other, an output side third lens that collimates each multi-wavelength light multiplexed by the output side grating in the plane direction, and the output side third lens Collimated The output-side second lens that collects each multi-wavelength light collected in a direction orthogonal to the plane direction, and each multi-wavelength light collected by the output-side second lens is collected in the plane direction. An output-side first lens, an output-side slab waveguide that passes each multi-wavelength light condensed by the output-side first lens, and an output that outputs each multi-wavelength light that has passed through the output-side slab waveguide An N × N wavelength selective switch comprising: an output-side waveguide branch circuit having a number N of output waveguides in which a plurality of waveguides as ports are arranged in parallel in the planar direction.

  The input second lens and the output second lens may be a common input / output second lens, and the input fourth lens and the output fourth lens may be a common input / output fourth lens.

  Hologram element for converting each single-wavelength light into a plurality of light beams at least before the input side two-dimensional MEMS mirror among the front stage of the input side two-dimensional MEMS mirror and the rear stage of the output side two-dimensional MEMS mirror Alternatively, a transmissive liquid crystal cell composed of a large number of pixels may be further provided.

  A quarter wavelength plate may be further provided between the hologram element or the transmissive liquid crystal cell and the input side two-dimensional MEMS mirror or the output side two-dimensional MEMS mirror.

  From the input waveguide end of the input-side waveguide branch circuit, the output waveguide end of the output-side waveguide branch circuit, the input-side two-dimensional MEMS mirror, and the spot size of the output-side two-dimensional MEMS mirror It is preferable that the spot size in the other part is enlarged.

  When the spot size of the input waveguide and the output waveguide and the focal length of the lens are selected so that the spot sizes in the input-side two-dimensional MEMS mirror and the output-side two-dimensional MEMS mirror are the same on each of them good.

  It is preferable to further include an optical fiber connected to the input waveguide end of the input side waveguide type branch circuit and / or the output waveguide end of the output side waveguide type branch circuit.

  The reflecting member may be formed of an independent reflecting plate or a reflecting film formed on the rear surface of the reflecting lens.

  Further, a corner cube for bending light rays 90 degrees into the input side two-dimensional MEMS mirror and the output side two-dimensional MEMS mirror at the front stage of the input side two-dimensional MEMS mirror and the rear stage of the output side two-dimensional MEMS mirror is further provided. It is good to prepare.

  The end face of the input side waveguide type branch circuit is polished at an angle of 5 degrees or more in order to reduce reflected return light from the end face of the input side waveguide type branch circuit, and the input side waveguide type The branch circuit is preferably arranged so as to be inclined so that multi-wavelength light emitted from the end face of the input-side waveguide branch circuit is perpendicularly incident on each subsequent lens.

  The input-side two-dimensional MEMS mirror and the output-side two-dimensional MEMS mirror may be driven by comb-shaped electrodes.

  The input side grating and the output side grating may be formed of a reflection type grating, and the input / output second lens and the input / output fourth lens may be formed of a common input / output lens.

  The features of the present invention are as follows: (1) Two waveguide branch circuits are used as an input port and an output port, respectively, and further, a grating is used so that the spectrally dispersed surface and the input / output port surface are orthogonal to each other. (2) A lens having a condensing function only in one direction, for example, a bowl shape, is combined with the optical system according to the orthogonal input / output port surface and the dispersion surface. 3) In order to switch the input / output port for each wavelength, two sets of two-dimensional MEMS mirrors were used to reflect light, and (4) a hologram element or a transmissive liquid crystal cell was used immediately before the two-dimensional MEMS mirror. There is that.

  According to the present invention, it is possible to provide an N × N wavelength selective switch capable of simultaneously performing DEMUX operation and MUX operation of two or more lights having the same wavelength.

1 is a perspective view showing an N × N wavelength selective switch according to an embodiment of the present invention. It is a top view which shows the NxN wavelength selective switch which concerns on embodiment of this invention. It is a side view which shows the NxN wavelength selective switch which concerns on embodiment of this invention. It is a figure which shows the usage example of the NxN wavelength selective switch which concerns on this invention. It is a perspective view which shows the NxN wavelength selective switch which concerns on the modification of this invention. (A) is a figure which shows an example of the phase distribution of the hologram element used for the NxN wavelength selective switch of FIG. 5, (b) is a top view which shows the NxN wavelength selective switch of FIG. It is a perspective view which shows the NxN wavelength selective switch which concerns on the other modification of this invention. It is a perspective view which shows the NxN wavelength selective switch which concerns on the other modification of this invention. It is a figure which shows one structural example of a certain node apparatus in a mesh network. It is a figure which shows the conventional 1 * N wavelength selective switch. It is a figure which shows another conventional 1 * N wavelength selective switch.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

  1 to 3 are views showing an N × N wavelength selective switch according to a preferred embodiment of the present invention. FIG. 1 is a perspective view, FIG. 2 is a top view, and FIG. 3 is a side view. First, the overall configuration will be described with reference to FIG. 1, and then the operation will be described.

  As shown in FIG. 1, the N × N wavelength selective switch 20 according to the embodiment has a number N of ports (N is an integer of 2 or more) having a plurality of input ports arranged in parallel in the plane direction (X direction in the drawing). An input-side waveguide type branch circuit 7a, and an output-side waveguide type branch circuit 7b having a number N of ports having a plurality of output ports arranged in parallel in the plane direction. When multi-wavelength light having a wavelength number M (M is an integer of 2 or more) is input to the input port, the multi-wavelength light is output from an arbitrary output port of the output-side waveguide branch circuit 7b for each wavelength. Is.

  The N × N wavelength selective switch 20 transmits the multi-wavelength light from the input-side waveguide type branch circuit 7a as it is in the plane direction and splits the wavelength for each wavelength in a direction orthogonal to the plane direction (Y direction in the drawing). N rows are arranged in the plane direction corresponding to the input means of the spectroscopic means and the input side waveguide type branch circuit 7a, and in a direction orthogonal to the plane direction corresponding to each single wavelength light dispersed by the spectroscopic means. An input-side two-dimensional MEMS mirror 16a having M rows and having a mirror that selectively reflects each single-wavelength light in the plane direction in an arbitrary direction in the plane direction, and each unit reflected by the input-side two-dimensional MEMS mirror 16a Reflecting means for reflecting the wavelength light, N rows arranged in the plane direction corresponding to each port of the output side waveguide type branch circuit 7b, and in the plane direction corresponding to each single wavelength light reflected by the reflecting means M in the orthogonal direction The output-side two-dimensional MEMS mirror 16b having a mirror that is arranged and reflects each single-wavelength light from the reflecting means toward a specific direction in the plane direction, and each single-wavelength light from the output-side two-dimensional MEMS mirror 16b, And a condensing unit that transmits the single wavelength light in the direction perpendicular to the plane direction and multiplexes each single wavelength light and outputs it from any output port of the output-side waveguide branch circuit 7b. And

  The input-side waveguide type branch circuit 7a includes an input waveguide 1a having a port number N in which a plurality of waveguides 2a to 6a as input ports to which multi-wavelength light having a wavelength number M is input are arranged in parallel in a plane direction, An input-side slab waveguide 8a that spreads the multi-wavelength light input to the input waveguide 1a in the plane direction.

  The spectroscopic means includes a first input-side lens 9a that collimates the multi-wavelength light spread by the input-side waveguide branch circuit 7a in the plane direction, and a multi-wavelength light collimated by the first input-side lens 9a. An input-side second lens that collimates in a direction orthogonal to the direction, an input-side third lens 11a that condenses the multi-wavelength light collimated by the input-side second lens in a plane direction, and an input-side third lens 11a The input side grating 12a that splits the collected multi-wavelength light for each wavelength in a direction orthogonal to the plane direction, and each single wavelength light that is split by the input side grating 12a is collimated in the direction orthogonal to the plane direction. And an input-side fourth lens.

  The input side two-dimensional MEMS mirror 16a has N rows of mirrors in the plane direction and M rows of mirrors in a direction perpendicular to the plane direction, and M rows of each single wavelength light collimated by the input side fourth lens. The angle at which each single-wavelength light reflected by the mirror at each wavelength and collimated by the input-side fourth lens is converted for each port by N rows of mirrors.

  The reflecting means includes a reflecting lens 13 that condenses each single wavelength light reflected by the input-side two-dimensional MEMS mirror 16a for each wavelength and converted for each port in the plane direction, and the reflecting lens 13. And a reflecting member 14 that reflects the single-wavelength light collected in step S1 to the reflecting lens 13 again.

  The output-side two-dimensional MEMS mirror 16b has N rows of mirrors in the plane direction and M rows of mirrors in a direction perpendicular to the plane direction, and is reflected by the reflecting member 14 and passes through the reflecting lens 13 again. The single wavelength light is reflected for each wavelength by the M rows of mirrors, and the traveling angle of each single wavelength light is converted for each port by the N rows of mirrors.

  The condensing means is an output-side fourth lens that condenses each single-wavelength light reflected by the output-side two-dimensional MEMS mirror 16b for each wavelength and converted in angle for each port in a direction orthogonal to the plane direction. The output-side grating 12b that combines the single-wavelength lights collected by the output-side fourth lens for each port in the direction orthogonal to the plane direction, and the multi-wavelength lights that are combined by the output-side grating 12b. Output side third lens 11b that collimates in the plane direction, output side second lens that collects each multi-wavelength light collimated by the output side third lens 11b in a direction perpendicular to the plane direction, and output side An output-side first lens 9b that condenses each multi-wavelength light collected by the second lens in a planar direction.

  The output-side waveguide type branch circuit 7b includes an output-side slab waveguide 8b that passes each multi-wavelength light collected by the output-side first lens 9b, and each multi-wavelength light that has passed through the output-side slab waveguide 8b. A plurality of waveguides 2b to 6b serving as output ports to be output have a number N of output waveguides 1b formed in parallel in the plane direction.

  In this embodiment, the input-side second lens and the output-side second lens are composed of a common input / output second lens 10, and the input-side fourth lens and the output-side fourth lens are common input / output fourth lenses. Consist of 15.

  Next, the configuration of each member will be described in detail.

  The input side waveguide type branch circuit 7 a and the output side waveguide type branch circuit 7 b are integrated on a flat substrate 21. In the present embodiment, the integrated circuit of the input side waveguide type branch circuit 7 a and the output side waveguide type branch circuit 7 b on the flat substrate 21 is referred to as a waveguide element 4.

  Further, the end face of the input side waveguide type branch circuit 7a is polished to an angle of 5 degrees or more in order to reduce the reflected return light from the end face of the input side waveguide type branch circuit 7a, and the input side waveguide The type branch circuit 7a is preferably arranged so as to be inclined so that the multi-wavelength light emitted from the end face of the input side waveguide type branch circuit 7a is perpendicularly incident on the subsequent lenses. Similarly, the end face of the output-side waveguide branch circuit 7b is polished to an angle of 5 degrees or more in order to reduce the reflected return light at the end face of the output-side waveguide branch circuit 7b, and the output-side guide The waveguide branch circuit 7b is preferably arranged so as to be inclined so that multi-wavelength light emitted from the end face of the input-side waveguide branch circuit 7a enters vertically.

  The input waveguide 1a end of the input side waveguide type branch circuit 7a and / or the output waveguide 1b end of the output side waveguide type branch circuit 7b, more specifically, to each of the waveguides 2a to 6a and 2b to 6b. Is connected to an optical fiber.

The waveguides 2a to 6a and 2b to 6b of the input side waveguide type branch circuit 7a and the output side waveguide type branch circuit 7b have a structure in which a core having a high refractive index is embedded in a clad having a lower refractive index. The input-side slab waveguide 8a and the output-side slab waveguide 8b have a light confinement structure only in the thickness direction, and when n is an equivalent refractive index of the slab waveguide, the slab waveguide The length is n × F _x1 (F _x1 is the focal length of the first lenses 9a and 9b).

The input side first lens 9a and the output side first lens 9b are lenses having a focal length F _x1 having a condensing function in a plane direction, and these are an input side waveguide type branch circuit 7a and an output side waveguide type branch circuit. 7b is arranged at a position corresponding to each.

The input / output second lens 10 is a lens having a focal length F _y having a condensing function in a direction orthogonal to the plane direction, and these lenses are arranged at a position F _y from the end face of the waveguide element 4.

The input side third lens 11a and the output side third lens 11b are lenses having a focal length F _x2 having a condensing function in a plane direction, and these are F _x1 from the input side first lens 9a and the output side first lens 9b. It is arranged at the position of + F _x2 .

  The input-side grating 12a and the output-side grating 12b are transmissive gratings having a dispersion axis whose light wavelength is dispersed in a direction orthogonal to the plane direction. These are the rear stage or the front stage of the input-side third lens 11a, and the output. It arrange | positions in the front | former stage or back | latter stage of the side 3rd lens 11b.

The reflecting means is disposed between the input side grating 12a and the output side grating 12b. The reflecting member 14 is made of a reflecting film formed on an independent reflecting plate or a subsequent surface of the reflecting lens 13. The reflection lens 13 is a lens having a focal length of 2 × F _x2 (twice F _x2 ) having a light collecting function in the plane direction.

O fourth lens 15, input-output and the second lens 10 are the same focal length lens having a F _y, which are arranged at a position of the input and output the second lens 10 from 2 × F _y (2 × F _y) Is done.

  The spot size of the input waveguide 1a and the output waveguide 1b and the focal length of the lens are selected so that the spot sizes on the input side two-dimensional MEMS mirror 16a and the output side two-dimensional MEMS mirror 16b are the same on each. It is.

The input side two-dimensional MEMS mirror 16a and the output side two-dimensional MEMS mirror 16b have M rows of mirrors in the direction of the dispersion axis of the input side grating 12a and the output side grating 12b, and the dispersion axis of the input side grating 12a and the output side grating 12b. And N rows of mirrors in a direction orthogonal to the input side third lens 11a and the output side third lens 11b are arranged at the position of F _x2 and are connected to the input side waveguide type branch circuit 7a and the output side guide. Arranged at positions corresponding to each of the waveguide branch circuits 7b.

  The input side two-dimensional MEMS mirror 16a and the output side two-dimensional MEMS mirror 16b are driven by comb-shaped electrodes.

  Next, the operation of the N × N wavelength selective switch 20 will be described with reference to FIG. 2 which is a top view and FIG. 3 which is a side view. The reason why the top view and the side view are described separately is as follows.

  First, the lens used has a condensing function (condensing action) only in the X direction or the Y direction, and the spatial input / output port switching is performed in the same plane (XZ plane: This is because the plane in which light is dispersed (YZ plane: this is referred to as a dispersion plane) is orthogonal to this.

  First, it demonstrates using FIG. 2 which is a top view. Here, a lens having a condensing function in the X direction, that is, the input side first lens 9a, the output side first lens 9b, the input side third lens 11a, the output side third lens 11b, and the reflection lens 13 are convex. The shape is represented by a solid line and has a condensing function in the Y direction, that is, the input / output second lens 10, the input / output fourth lens 15, and the input side grating 12 a and the output side grating that split in the Y direction. 12b is a rectangle and is represented using a broken line. As described above, the optical element indicated by the broken line will be described as having no influence on the switching surface.

  Consider a case where multi-wavelength light composed of various wavelength signals is incident on the waveguide 2a of the input waveguide 1a (configured of the waveguides 2a to 6a). Note that the input waveguide can realize substantially the same operation regardless of which waveguide is selected.

The input-side first lens 9a having a focal length F _x1 is disposed on the end face of the waveguide element 4. At the subsequent stage, the input-side third lens 11a having the focal length F _x2 is almost from the first lens 9a. The input-side two-dimensional MEMS mirror 16a is disposed at a distance of F _x2 from the input-side third lens 11a, and is disposed at a distance of (F _x1 + F _x2 ). Therefore, an incident light distribution in which the light spot size in the X direction in the waveguide 2a is enlarged or reduced at a magnification of F _x2 / F _x1 is projected onto the input-side two-dimensional MEMS mirror 16a.

  Now, when the multi-wavelength light input to the waveguide 2a enters the input-side slab waveguide 8a, there is no lateral confinement, so that it spreads by diffraction and is collimated when transmitted through the input-side first lens 9a. Thereafter, when the light passes through the input side third lens 11a, the light is condensed and projected onto the input side two-dimensional MEMS mirror 16a. Each mirror of the input side two-dimensional MEMS mirror 16a corresponds to each waveguide (2a to 6a). The light projected on the input side two-dimensional MEMS mirror 16a is incident on the reflecting lens 13 and the reflecting member 14 disposed in the vicinity thereof at various angles according to the rotation angle of the mirror. The reflecting lens 13 has a focal length approximately twice that of the input-side third lens 11a. Since the light reflected by the reflecting member 14 passes through the reflecting lens 13 again, the reflecting lens 13 and the reflecting member 14 can be handled equivalently to a lens having a thickness twice that of the reflecting lens 13. Therefore, the Fourier image of the input side two-dimensional MEMS mirror 16a is condensed on the output side two-dimensional MEMS mirror 16b. This incident light can be incident on an arbitrary mirror constituting the output side two-dimensional MEMS mirror 16b by changing the angle of the input side two-dimensional MEMS mirror 16a.

  On the other hand, by making the angle of each mirror constituting the output-side two-dimensional MEMS mirror 16b an appropriate angle, light is incident on the output-side third lens 11b, and then collimated to be output with the output-side first lens 9b. The position of the waveguide (2b to 6b) that is incident on the side waveguide type branch circuit 7b and is output can be changed according to the incident position (in FIG. 2, the angle of the input side two-dimensional MEMS mirror 16a) To change the position of the output waveguides (5b, 6b).

  Next, the operation will be described with reference to FIG. 3 which is a side view. This plane is a YZ plane, that is, a dispersion plane, and represents an operation in a plane in which the wavelength is dispersed. The optical element indicated by the broken line will be described as having no influence on the dispersion surface.

  First, the configuration will be described. The input / output second lens 10 and the input side grating 12a are sequentially arranged from the waveguide element 4 at the same interval as the focal length Fy of the input / output second lens 10 (the reflection member 14 and the output side grating 12b at the same position when viewed from the dispersion surface). Are arranged so as to be the input / output fourth lens 15 and the input side two-dimensional MEMS mirror 16a (the output side two-dimensional MEMS mirror 16b is arranged at the same position).

Now, the multi-wavelength light emitted from the waveguide element 4 is collimated after passing through the input / output second lens 10 having the focal length F _y , and is split in different directions for each wavelength when passing through the input side grating 12a. The When the split single wavelength light enters the input / output fourth lens 15, it is projected onto the input-side two-dimensional MEMS mirror 16 a while being condensed as parallel light rays (1).

  On the other hand, each mirror rotates around the Y axis as described above, but does not rotate around the X axis, and thus acts as a simple flat mirror on the dispersion surface, so that each single wavelength light travels in the opposite direction. The light enters the reflecting member 14 (2).

  Thereafter, the angle reflected by the reflecting member 14 and the traveling angle of each single-wavelength light is inverted in the vertical direction, and is again condensed on the output-side two-dimensional MEMS mirror 16b by the input / output fourth lens 15 as light rays parallel to each other. Incident (3).

  Thereafter, each single-wavelength light reflected by the output-side two-dimensional MEMS mirror 16b is collected by the input / output fourth lens 15, and is combined again by the output-side grating 12b to become parallel collimated multi-wavelength light, The light is collected by the input / output second lens 10, enters the waveguide element 4, and is output from each waveguide (2 b to 6 b) of the output waveguide 1 b (4).

  The N × N wavelength selective switch 20 described above has an N-side input-side waveguide branch circuit 7a having a plurality of input ports arranged in parallel in the plane direction, and a plurality of output ports arranged in parallel in the plane direction. An output-side waveguide branch circuit 7b having N ports, and when the multi-wavelength light having the wavelength number M is input to one input port of the input-side waveguide branch circuit 7a, the wavelength of the multi-wavelength light is changed. Every time, it is possible to output from an arbitrary output port of the output side waveguide type branch circuit 7b. Further, light of the same wavelength incident from a plurality of ports of the output side waveguide type branch circuit 7b can be output from a plurality of different ports of the input side waveguide type branch circuit 7a.

  As a result, the N × N wavelength selective switch 20 alone can simultaneously perform two or more lights having the same wavelength in the DEMUX operation and the MUX operation.

  Further, since the input side waveguide type branch circuit 7a and the output side waveguide type branch circuit 7b are constituted by channel waveguides of several microns square, a branch circuit having 100 ports or more can be easily realized. A large-scale switch such as the existing 100 × 100 wavelength selective switch can also be realized.

  In addition, the light distribution output from the input-side waveguide branch circuit 7a has an elliptical shape with a large ellipticity, but has a light collecting function only in one direction as in the present invention. By using the lens, it is possible to control the light distribution (eg, ellipticity) to the conventional MEMS mirror that has a large light beam diameter.

  That is, in the N × N wavelength selective switch 20, the input waveguide 1a end of the input side waveguide type branch circuit 7a, the output waveguide 1b end of the output side waveguide type branch circuit 7b, the input side two-dimensional MEMS mirror 16a, Since the spot size in the portion other than the spot size in the output-side two-dimensional MEMS mirror 16b is enlarged, the dimensions of the mirrors constituting the input-side two-dimensional MEMS mirror 16a and the output-side two-dimensional MEMS mirror 16b are reduced. Thus, it is possible to reduce the cost for manufacturing the input side two-dimensional MEMS mirror 16a and the output side two-dimensional MEMS mirror 16b. This is because, in general, a MEMS mirror forms a movable mirror by forming a metal thin film on a sacrificial layer (which will be etched away later) and etching away the sacrificial layer. Because warpage and deformation are likely to occur due to stress generated during the production of thin films, and the size of the mirror increases, it becomes extremely difficult to reduce this warpage and deformation, yield is poor, control methods are difficult, and extremely expensive. It is.

  In essence, the complicated node device shown in FIG. 9 can be replaced by a single N × N wavelength selective switch 20, and a significant cost reduction effect and size reduction are possible.

  FIG. 4 shows an example of use of the N × N wavelength selective switch 20 according to the present invention. Compared to the prior art shown in FIG. 9, the system configuration is extremely simple, and the apparatus can be significantly downsized. In addition, since a large number of optical splitters used in the prior art are not used, the loss is low, the need for an expensive optical amplifier is eliminated, and the cost can be greatly reduced. The expansion of the input / output port of the waveguide element and the expansion of the MEMS mirror are extremely easy, so the expansion of the port assigned to the wavelength tunable receiver / wavelength tunable transmitter can be flexibly supported.

  In other words, it will be introduced to a wide range of networks from the metro core network to the metro edge and access systems, leading to innovative development of optical networks.

  The present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in order to realize a function of broadcasting a signal of the same wavelength to all output ports, as shown in FIG. 5, in the N × N wavelength selective switch 20 of FIG. 1, the front stage of the input side two-dimensional MEMS mirror 16a and A hologram element (or a transmissive liquid crystal composed of a large number of pixels) for converting each single-wavelength light into a large number of light beams is provided at least before the input side two-dimensional MEMS mirror 16a in the subsequent stage of the output side two-dimensional MEMS mirror 16b. Cell) 17 may be further provided. In the case of using a transmissive liquid crystal cell, it is more preferable to provide both the front stage of the input side two-dimensional MEMS mirror 16a and the rear stage of the output side two-dimensional MEMS mirror 16b.

  Here, when the hologram element 17 is a hologram element having a periodic phase distribution as shown in FIG. 6A, the light reflected from the input side two-dimensional MEMS mirror 16a as shown in FIG. The beam is divided into several (here, three) beams, propagates, enters the waveguide element 4, and exits from the output waveguide 1b. That is, incident light can be broadcast to several waveguides.

  This beam splitting depends on the shape of the phase distribution of the hologram element 17, and various split patterns (number of splits and split ratios) can be realized. In addition, when a transmissive liquid crystal cell is used instead of the hologram element, the state of broadcasting in time can be changed by changing the electric field distribution applied to the transmissive liquid crystal cell. Further, it is possible to correct the deviation (unevenness) in the flatness of the mirrors of the two-dimensional MEMS mirrors 16a and 16b and to regard it as an ideal flat state.

  A quarter wavelength plate 18 may be further provided between the hologram element (or transmission type liquid crystal cell) 17 and the input side two-dimensional MEMS mirror 16a or the output side two-dimensional MEMS mirror 16b. By doing so, the input light passes through the quarter-wave plate 18 twice before and after the reflection by the input side MEMS mirror 16a, so that the hologram element (or the polarization vibration direction is rotated by 90 degrees at the time of incidence and at the time of reflection) Because the light passes back and forth through the transmission type liquid crystal cell) 17, a polarization-independent phase modulation operation is possible.

  Therefore, a multi-spot with various power distributions can be realized by using the hologram element (or transmissive liquid crystal cell) 17 immediately before the input side two-dimensional MEMS mirror 16a, that is, immediately before, so that a low-loss broadcast function is possible. It becomes.

  In addition, as shown in FIG. 7, in the N × N wavelength selective switch 20 of FIG. 1, reflection type gratings 12a ′ and 12b ′ are used as the input side grating 12a and the output side grating 12b, and the input / output second lens 10 is input. The output fourth lens 15 may be a common input / output lens 19.

In this case, when the hologram element 17, the quarter wavelength plate 18, and the input side two-dimensional MEMS mirror 16a are opposed to the reflective grating 12a ′, and the output side two-dimensional MEMS mirror 16b is opposed to the reflective grating 12b ′. good. In this case, the light reflected by the reflective grating 12a ′ and the reflective grating 12b ′ passes back and forth through the input-side third lens 11a ′ and the output-side third lens 11b ′. Since they are equivalent, the focal lengths of the input-side third lens 11a ′ and the output-side third lens 11b ′ are the focal lengths F of the input-side third lens 11a and the output-side third lens 11b when a transmissive grating is used. 2 × F _x2 is better than _x2 .

  The multi-wavelength light emitted from the input-side waveguide type branch circuit 7a sequentially enters the input-side first lens 9a, the input / output lens 19, the input-side third lens 11a ′, and the reflection-type grating 12a ′. The light is dispersed and reflected by the grating 12a ′. Each single-wavelength light spectrally reflected by the reflective grating 12a ′ is reflected on the input side third lens 11a ′, the input / output lens 19, the hologram element 17, the quarter wavelength plate 18, and the input side two-dimensional MEMS mirror 16a. Are sequentially incident and reflected by the input side two-dimensional MEMS mirror 16a. Each single wavelength light reflected by the input side two-dimensional MEMS mirror 16a sequentially enters the quarter wavelength plate 18, the hologram element 17, the input / output lens 19, the reflection lens 13 and the reflection member 14, and this reflection member. 14 is reflected. Each single wavelength light reflected by the reflecting member 14 sequentially enters the reflecting lens 13, the input / output lens 19, and the output side two-dimensional MEMS mirror 16b, and is reflected by the output side two-dimensional MEMS mirror 16b. Each single wavelength light reflected by the output side two-dimensional MEMS mirror 16b sequentially enters the input / output lens 19, the output side third lens 11b 'and the reflection type grating 12b', and is multiplexed by the reflection type grating 12b '. And reflected. The multi-wavelength lights combined and reflected by the reflective grating 12b ′ are sequentially incident on the output side third lens 11b ′, the input / output lens 19 and the output side first lens 9b, and the output side waveguide type branch circuit 7b. It is emitted from.

  Further, as shown in FIG. 8, in each of the above-described embodiments, the input-side waveguide type branch circuit 7a and the output-side waveguide type branch circuit 7b are not integrated on one substrate 21, but are individually separated from each other. You may implement | achieve using 21b.

  Although not shown, in the N × N wavelength selective switch 20 of FIG. 1, the light beam is bent 90 degrees before the input side two-dimensional MEMS mirror 16a and after the output side two-dimensional MEMS mirror 16b. A corner cube that enters and exits the two-dimensional MEMS mirror 16a and the output-side two-dimensional MEMS mirror 16b may be further provided. A light beam bent 90 degrees by the corner cube is transmitted through the hologram element 17 and the quarter-wave plate 18. And may be projected onto the two-dimensional MEMS mirrors 16a and 16b.

  In short, according to the present invention, it is possible to provide an N × N wavelength selective switch capable of simultaneously performing DEMUX operation and MUX operation of two or more lights having the same wavelength.

DESCRIPTION OF SYMBOLS 1a Input waveguide 1b Output waveguide 4 Waveguide element 7a Input side waveguide type branch circuit 7b Output side waveguide type branch circuit 8a Input side slab waveguide 8b Output side slab waveguide 9a Input side first lens 9b Output side first 1 lens 10 Input / output second lens 11a Input side third lens 11b Output side third lens 12a Input side grating 12b Output side grating 13 Reflecting lens 14 Reflecting member 15 Input / output fourth lens 16a Input side two-dimensional MEMS mirror 16b Output Side 2D MEMS mirror 20 N × N wavelength selective switch

Claims (13)

An input side waveguide type branch circuit having N ports (N is an integer of 2 or more) having a plurality of input ports arranged in parallel in the plane direction;
A number N of output-side waveguide branch circuits having a plurality of output ports arranged in parallel in the planar direction;
With
When multi-wavelength light having a wavelength of M (M is an integer of 2 or more) is input to one input port of the input-side waveguide branch circuit, the multi-wavelength light is output to the output-side waveguide branch for each wavelength. An N × N wavelength selective switch for outputting from any output port of the circuit,
A spectroscopic means for splitting the multi-wavelength light from the input-side waveguide type branch circuit for each wavelength in a direction orthogonal to the planar direction;
N rows are arranged in the plane direction corresponding to each input port of the input side waveguide type branch circuit, and M in a direction orthogonal to the plane direction corresponding to each single wavelength light dispersed by the spectroscopic means. An input-side two-dimensional MEMS mirror having a mirror arranged in a row and selectively reflecting each single wavelength light in the planar direction in an arbitrary direction in the planar direction;
Reflecting means for reflecting each single wavelength light reflected by the input side two-dimensional MEMS mirror;
N rows are arranged in the planar direction corresponding to each port of the output-side waveguide branch circuit, and M rows in a direction orthogonal to the planar direction corresponding to each single wavelength light reflected by the reflecting means. An output-side two-dimensional MEMS mirror having a mirror that is arranged and reflects each single wavelength light from the reflecting means toward a specific direction in the planar direction;
Condensing each single-wavelength light from the output-side two-dimensional MEMS mirror and combining each single-wavelength light in a direction orthogonal to the planar direction from any output port of the output-side waveguide branch circuit Means,
An N × N wavelength selective switch comprising: An input waveguide having a number of ports N (N is an integer of 2 or more) in which a plurality of waveguides as input ports to which multi-wavelength light having a wavelength of M (M is an integer of 2 or more) is input are arranged in parallel in the plane direction And an input-side waveguide type branch circuit having an input-side slab waveguide that spreads the multi-wavelength light input to the input waveguide in the planar direction,
An input-side first lens that collimates multi-wavelength light spread by the input-side waveguide-type branch circuit in the planar direction;
An input-side second lens that collimates the multi-wavelength light collimated by the input-side first lens in a direction orthogonal to the planar direction;
An input-side third lens that condenses the multi-wavelength light collimated by the input-side second lens in the plane direction;
An input side grating that splits the multi-wavelength light collected by the input side third lens for each wavelength in a direction orthogonal to the planar direction;
An input-side fourth lens that collimates each single-wavelength light split by the input-side grating in a direction orthogonal to the planar direction;
It has N rows of mirrors in the plane direction and M rows of mirrors in a direction perpendicular to the plane direction, and each single wavelength light collimated by the input-side fourth lens for each wavelength by the M rows of mirrors. An input-side two-dimensional MEMS mirror that converts the traveling angle of each single-wavelength light reflected and collimated by the input-side fourth lens for each port by an N-row mirror;
A reflecting lens that collects each single wavelength light reflected by the input-side two-dimensional MEMS mirror for each wavelength and converted for each port in the plane direction;
A reflecting member that reflects each single-wavelength light collected by the reflecting lens to the reflecting lens again;
There are N rows of mirrors in the plane direction and M rows of mirrors in a direction orthogonal to the plane direction, and each single wavelength light reflected by the reflecting member and passed through the reflecting lens again is M rows. An output-side two-dimensional MEMS mirror that reflects each wavelength by the mirror and converts the angle of travel of each single wavelength light for each port by an N-row mirror;
An output-side fourth lens that collects each single-wavelength light reflected at each wavelength by the output-side two-dimensional MEMS mirror and converted in an angle that travels for each port in a direction orthogonal to the planar direction;
An output-side grating that multiplexes each single wavelength light collected by the output-side fourth lens for each port in a direction orthogonal to the planar direction;
An output-side third lens that collimates each multi-wavelength light combined by the output-side grating in the plane direction;
An output-side second lens that condenses each multi-wavelength light collimated by the output-side third lens in a direction perpendicular to the planar direction;
An output-side first lens that collects each multi-wavelength light collected by the output-side second lens in the planar direction;
An output-side slab waveguide that passes each multi-wavelength light condensed by the output-side first lens, and a plurality of waveguides as output ports that output each multi-wavelength light that has passed through the output-side slab waveguide An output-side waveguide type branch circuit having an N-port output waveguide formed in parallel in the planar direction;
An N × N wavelength selective switch comprising:   The input-side second lens and the output-side second lens are composed of a common input / output second lens, and the input-side fourth lens and the output-side fourth lens are composed of a common input / output fourth lens. N × N wavelength selective switch described in 1.   Hologram element for converting each single-wavelength light into a plurality of light beams at least before the input side two-dimensional MEMS mirror among the front stage of the input side two-dimensional MEMS mirror and the rear stage of the output side two-dimensional MEMS mirror The N × N wavelength selective switch according to claim 3, further comprising a transmissive liquid crystal cell including a plurality of pixels.   5. The N × N wavelength selective switch according to claim 4, further comprising a ¼ wavelength plate between the hologram element or the transmissive liquid crystal cell and the input side two-dimensional MEMS mirror or the output side two-dimensional MEMS mirror.   From the input waveguide end of the input-side waveguide branch circuit, the output waveguide end of the output-side waveguide branch circuit, the input-side two-dimensional MEMS mirror, and the spot size of the output-side two-dimensional MEMS mirror The N × N wavelength selective switch according to claim 3, wherein a spot size in another portion is enlarged.   The spot size of the input waveguide and the output waveguide and the focal length of the lens are selected so that the spot sizes of the input-side two-dimensional MEMS mirror and the output-side two-dimensional MEMS mirror are the same on each. Item 7. The N × N wavelength selective switch according to any one of Items 3 to 6.   The optical fiber connected to the said input waveguide end of the said input side waveguide type branch circuit and / or the said output waveguide end of the said output side waveguide type branch circuit is further provided in any one of Claims 3-7. N × N wavelength selective switch.   9. The N × N wavelength selective switch according to claim 3, wherein the reflection member is formed of an independent reflection plate or a reflection film formed on a rear surface of the reflection lens.   Further, a corner cube for bending light rays 90 degrees into the input side two-dimensional MEMS mirror and the output side two-dimensional MEMS mirror at the front stage of the input side two-dimensional MEMS mirror and the rear stage of the output side two-dimensional MEMS mirror is further provided. An N × N wavelength selective switch according to any one of claims 3 to 9.   The end face of the input side waveguide type branch circuit is polished at an angle of 5 degrees or more in order to reduce reflected return light from the end face of the input side waveguide type branch circuit, and the input side waveguide type The branch circuit is arranged to be inclined so that multi-wavelength light emitted from the end face of the input-side waveguide branch circuit is perpendicularly incident on each subsequent lens. The described N × N wavelength selective switch.   The N × N wavelength selective switch according to claim 3, wherein the input side two-dimensional MEMS mirror and the output side two-dimensional MEMS mirror are driven by comb-shaped electrodes.   13. The N × according to claim 3, wherein the input side grating and the output side grating are made of a reflection type grating, and the input / output second lens and the input / output fourth lens are made of a common input / output lens. N wavelength selective switch.