JP2015022242A - Optical switch and optical switch system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an optical switch which, by switching without using an electric signal, enlarges the scale, increases throughput, and reduces power consumption.SOLUTION: An input-use slab waveguide 110 and an output-use slab waveguide 120 are connected by a plurality of array waveguides 130a-130k. Each of the array waveguides 130a-130k has inserted therein nonlinear media 131a-131k differing in length in the order stated. When a pump light Pand a signal light Pare inputted in synchronism, the nonlinear media 131a-131k have their refractive index changed in accordance with the intensity of the pump light Pand imparted a phase difference, so that a port, among the output ports of the output-use slab waveguide 120, from which the signal light Pis outputted changes.

Description

  The present invention relates to a large-scale optical switch, which is a basic part of a router or switch used in optical information communication, and an optical switch system using this optical switch.

  Optical communication has the features of large capacity and ultra-high speed, and has been put into practical use in many information communication networks in recent years. The path configuration of such an optical communication network is simplest in a point-to-point connection that connects two points with individual optical fibers.

  On the other hand, it has been proposed to switch a light signal at each node by accommodating a plurality of paths in one optical fiber by utilizing the large capacity of the optical fiber.

For example, in optical path switching, the wavelength of an optical signal is associated with a path, and the path can be switched for each wavelength using an arrayed waveguide grating (AWG), a wavelength selective optical switch, or the like.
However, the number of paths is limited by the number of wavelengths that can be set.

Furthermore, optical packet switching (OPS) that switches paths in units of optical packets has been proposed. In this method, label information is added to each optical packet to correspond to the path, and the label is recognized at each node. In each node, an optical packet is switched to a route according to a label using an optical switch.
Since this method can increase the number of paths without being restricted by the number of wavelengths, a more flexible network can be constructed.

  The optical switch used here is an indispensable component having a function of switching an incoming optical packet to a port corresponding to the next transmission destination at high speed.

  What is realized as such an optical switch is a wavelength selective optical switch composed of a tunable semiconductor laser and an arrayed waveguide grating (AWG), and a micro electro mechanical system (MEMS). And a phased array type spatial light switch using an electro-optic effect.

  In such an optical switch, as the demand for network traffic increases, not only the speed is increased, but also the scale is increased, that is, the number of ports is increased, and a large number of optical packets can be processed per unit time, that is, the throughput is increased. Power consumption is required.

Ibrahim Murat Soganci, et al., "Monolithically Integrated InP 1 x 16 Optical Switch With Wavelength-Insensitive Operation", IEEE PHOTONICS TECHNOLOGY LETTERS, Vol. 22, No. 3, PP.143-145, 2010. Katsunari Okamoto, “Fundamentals of Optical Waveguides, 2nd edition”, PP. 424-425, Elsevier, 2006, ISBN: 978-0-12-525096-2. Hisaya Oda, et al., "Self-phase modulation in photonic-crystal-slab line-defect waveguides", Applied Physics Letters, 90, 231102, 2007.

  The optical switch as described above has the following problems.

  In the wavelength selective optical switch, in order to realize high-speed switching, it is necessary to use a wavelength-tunable semiconductor laser having a complicated configuration capable of changing the wavelength at high speed. For this reason, there is a concern about cost increase.

  In addition, a spatial optical switch using MEMS has an advantage that it can be easily scaled up, but there is a limit to speeding up because the switching speed of MEMS is about microseconds to milliseconds.

  A phased array type spatial optical switch is promising as a spatial optical switch because it can perform phase modulation in the arrayed waveguide section and modulate the converging position in the slab waveguide to switch the output port. (Refer nonpatent literature 1).

However, the above spatial light switch has the following problems.
First, since the phase of each arrayed waveguide is electrically changed using the electro-optic effect or the carrier effect, a large number of electrodes and an electric control device associated therewith are required, resulting in high cost and high power consumption.
Further, since the optical packet is spatially switched as it is, the input port and the output port are occupied by the occupied time of the packet at the same time. For this reason, there is a problem that it is impossible to switch a plurality of packets received at the same time by one element.
For this reason, there has been a limit to the large-scale space optical switch, high throughput, and low power consumption.

  An object of the present invention is to provide an optical switch and an optical switch system capable of increasing the scale, increasing the throughput, and reducing the power consumption of the optical switch in view of the above-described conventional technology.

The optical switch of the present invention that solves the above problems is as follows.
An input slab waveguide that includes a plurality of input ports and a plurality of output ports, and outputs light from each of the output ports when light is input from any of the input ports. When,
The same number of input ports as the output ports of the input slab waveguide, and a plurality of output ports, and according to the relative phase difference of each light input to the input port, An slab waveguide for output in which one output port from which light is output is determined,
A plurality of arrayed waveguides adjacent to each other in the order in which the output port of the slab waveguide for input and the input port of the slab waveguide for output are individually connected;
Each time it is inserted into each of the arrayed waveguides, and the length of each of the arrayed waveguides is shifted from the adjacent one of the arrayed waveguides to the adjacent adjacent one of the arrayed waveguides, the length is sequentially constant. A long non-linear medium,
Have
The input light of the input slab waveguide is input with pump light and signal light having a wavelength different from that of the pump light and synchronized with the pump light.
One output port from which the signal light is output is determined among a plurality of output ports of the output slab waveguide according to a change in the refractive index of the nonlinear medium due to the pump light.

  In the optical switch of the present invention, the pulse width of the signal light is narrower than the pulse width of the pump light.

  In the optical switch of the present invention, each of the output ports of the output slab waveguide is provided with a wavelength filter that removes the pump light and transmits the signal light.

In the optical switch of the present invention, the nonlinear medium is composed of lithium niobate,
The input slab waveguide, the output slab waveguide, the arrayed waveguide, and the nonlinear medium are integrated in a quartz-based planar lightwave circuit.

  The optical switch according to the present invention is characterized in that the arrayed waveguide and the nonlinear medium are monolithically integrated with semiconductor materials having different bandgap wavelengths and waveguide structures.

  In the optical switch of the present invention, the nonlinear medium is composed of a photonic crystal.

  In the optical switch of the present invention, a 3R regenerator is connected to each of the output ports of the output slab waveguide.

The optical switch system of the present invention is
Any one of the above optical switches;
A first short pulse light source that generates short pulse light for pump light;
A second short pulse light source that generates a short pulse light for signal light having a wavelength different from that of the short pulse light for pump light and synchronized with the short pulse light for pump light;
A plurality of optical control circuits having an optical attenuation selector, an all-optical gate, and an optical coupler, and sending light output from the optical coupler to an input port of the optical switch;
The short pulse light for the pump light generated from the first short pulse light source is branched and propagated to the plurality of optical attenuation selectors with different delay amounts of the branched short pulse light for the pump light. A first branch / delay circuit;
The short pulse light for signal light generated from the second short pulse light source is branched, the amount of delay of the branched short pulse light for signal light is made different, and the delay state is the first branch / delay A second branch / delay circuit that propagates to each of the plurality of all optical gates in the same manner as the delay state in the circuit,
Each of the optical attenuation selectors branches the short pulse light for the pump light propagated by the first branch / delay circuit into a plurality of parts, and has different attenuation intensity with respect to the branched short pulse light. Attenuate and output one of the branched and attenuated pulsed light as pump light,
Each of the all-optical gates transmits the short pulse light for signal light propagated by the second branch / delay circuit when there is control light corresponding to optical packet information inputted from the outside. Attenuate when there is no control light, and output as signal light,
Each of the optical couplers combines the pump light output from the optical attenuation selector and the signal light output from the all-optical gate synchronized with the pump light, and It is sent to one of the input ports.

  According to the present invention, an optical switch capable of switching the output port with an optical signal without using an electric signal and simultaneously switching a plurality of packet signals can achieve large scale, high throughput, and low power consumption. In addition, an optical switch system can be realized.

It is a block diagram which shows the optical switch which concerns on the Example of this invention. It is explanatory drawing which shows the design method of a nonlinear medium. It is a block diagram which shows the optical switch system which concerns on the Example of this invention.

  Hereinafter, an optical switch and an optical switch system according to the present invention will be described in detail based on examples.

[Example 1]
FIG. 1 shows an optical switch 10 according to Embodiment 1 of the present invention. The optical switch 10 includes a switch fabric unit 100 and a plurality of 3R regenerators 140.
The 3R regenerator 140 is a regenerator having three functions of amplification (Re-amplification), timing reproduction (Re-timing), and waveform shaping (Re-shaping).

  The switch fabric unit 100 includes an input slab waveguide 110, an output slab waveguide 120, and a plurality (11 in this example) of arrayed waveguides 130a to 130k.

The input slab waveguide 110 includes a plurality (five in this example) of input ports 111a to 111e and a plurality (11 in this example) of output ports 112a to 112k.
In this case, when light is input from any one of the input ports 111a to 111e, the input slab guide is such that the light distributed with equal light intensity is output from the output ports 112a to 112k. The distribution characteristics of the waveguide 110 are designed.

The output slab waveguide 120 includes a plurality (five in this example) of output ports 121a to 121e and a plurality (11 in this example) of input ports 122a to 122k.
In this case, according to the relative phase difference of each light input to each input port 122a-122k, one input port (out of the output ports 121a-121e) in which each input light interferes and condenses. The light collection characteristic of the output slab waveguide 120 is designed so that any one of the output ports) is determined.

The output ports 112a to 112k of the input slab waveguide 110 and the input ports 122a to 122k of the output slab waveguide 120 are individually connected by a plurality of arrayed waveguides 130a to 130k that are adjacent in sequence. ing.
That is, the input ends of the arrayed waveguides 130 a to 130 k are connected to the output ports 112 a to 112 k of the input slab waveguide 110, and the arrayed waveguides 130 a to 130 k are connected to the input ports 122 a to 122 k of the output slab waveguide 120. Output terminal is connected.

  The arrayed waveguides 130a to 130k are set to the same length. However, when the arrayed waveguide lengths are not set to the same length due to physical layout restrictions or the like, they can be varied by a predetermined length. For example, the array waveguide 130a on the uppermost side is the shortest, and each time the array waveguide is directed to the lower array waveguide 130k, the arrayed waveguides are sequentially increased by a certain length. Here, in order to simplify the description, the arrayed waveguides 130a to 130k are set to the same length.

Furthermore, nonlinear media 131a to 131k having different lengths are individually inserted into the respective arrayed waveguides 130a to 130k.
For example, the length of the nonlinear medium 131a of the one array waveguide 130a located on the uppermost side in FIG. 1 is the shortest, and the length of the nonlinear medium 131k of the other array waveguide 130k located on the lowermost side in FIG. Thus, each time the nonlinear medium 131a moves from the upper nonlinear medium 131a to the lower nonlinear medium 131k, the length of each nonlinear medium is sequentially increased by a certain length. As a result, light with a phase difference is output from each output end of the arrayed waveguides 130a to 130k.

  In the nonlinear media 131a to 131k, it is known that when an electric field is applied, the refractive index changes according to the applied electric field strength due to the Kerr effect. Due to this effect, even when the electric field generated when strong light is incident, that is, when the electric field causing the Kerr effect is an optical electric field, the refractive index can be similarly changed. Therefore, if the refractive index of the nonlinear medium 131a to 131k is changed by the optical Kerr effect, the phase of light passing therethrough, that is, signal light (described later) can be changed to a predetermined value. Since this phenomenon is very fast, even a signal light having a short pulse width can sufficiently change the phase.

Pump light P _P and signal light P _S are input to any one of the input ports 111 a to 111 e (for example, input port 111 c) of the input slab waveguide 110.
The pump light P _P is short pulse light having a predetermined constant period. The signal light P _S is synchronized with the pump light P _P and has short pulse light only when the logic level is 1.
The pulse width of the pump light P _P is a example 1.6 ps, a pulse width of the signal light P _S has a example 1.4Ps. That is, the pulse width of the signal light P _S is narrower than the pulse width of the pump light P _P. The wavelengths of the pump light P _P and the signal light P _S are different.

A plurality (five in this example) of 3R regenerators 140 are individually connected to the output ports 121a to 121e of the output slab waveguide 120, respectively.
Although not shown in the figure, the pump light P _P is removed and the signal light P _S is passed through the output ports 121 a to 121 e of the output slab waveguide 120 and before the 3R regenerator 140. Each of the wavelength filters to be transmitted is installed.

  Next, the operation of the optical switch 10 having the above configuration will be described.

The pump light P _P and the signal light P _S that are short pulse lights are equal when input to any one of the input ports 111 a to 111 e (for example, the input port 111 c) of the input slab waveguide 110. The light intensity is distributed to the output ports 112a to 112k and further input to the arrayed waveguides 130a to 130k.

The operation when the short pulse light propagates through each of the arrayed waveguides 130a to 130k will be described as follows when the pump light P _P is present and when there is no pump light P _P.

First, let us consider a case where there is no pump light P _{P, that} is, a case where there is no refractive index change in the nonlinear media 131a to 131k.
In this case, each signal light P _S propagates from the input end to the output end of each of the arrayed waveguides 130a to 130k, so that each signal light P _S is input to the output slab waveguide 120, respectively.
Each signal light P _S interferes with the output slab waveguide 120, and output is focused at a predetermined output port (one of the output ports of the output port 121a~121e). Here, for example, it is output from the top output port 121a in FIG.

Next, consider the case where there is pump light P _P, that is, the case where there is a refractive index change in the nonlinear media 131a to 131k.
At this time, the refractive index change given by the nonlinear medium 131A～131k of each arrayed waveguide 130a~130k corresponds to the length of the intensity of the pump light P _P and nonlinear medium 131A～131k.

As described above, the length of the nonlinear medium 131A～131k, since the set to be longer toward the lower side (nonlinear medium 131k) from above (nonlinear medium 131a) in FIG. 1, the pump light P _P When the refractive index change occurs in the nonlinear mediums 131a to 131k with the input, the lower one of the arrayed waveguides 130a to 130k becomes equivalently longer.
For this reason, when each signal light P _S output from each of the arrayed waveguides 130a to 130k is caused to interfere with the output slab waveguide 120, the signal light P _S is compared with the case where there is no change in the refractive index. In FIG. 1, the light is condensed on the output port below the uppermost output port 121a.

The condensing position, that is, the output port 121a~121e signal light P _S, and outputs the condensed, can be varied by adjusting the refractive index variation in the nonlinear medium 131A～131k. That is, the length of the intensity of the pump light P _P and nonlinear medium 131a~131k by setting a desired value, it can be adjusted.
Accordingly, by setting the lengths of the nonlinear media 131a to 131k in a desired length in advance and adjusting the intensity of the pump light P _P , the signal light P _S is output from any output port among the output ports 121a to 121e. Can be output.

The signal light P _S output from one of the output ports 121a to 121e passes through the wavelength filter, and is then 3R regenerated by the 3R regenerator 140 and regenerated to a desired modulation format.

Next, a specific design method for the length of the nonlinear medium will be described with reference to FIG.
Here, a switch structure composed of an input port, an output port, a slab waveguide, an arrayed waveguide, and a nonlinear medium waveguide, the refractive index change necessary for switching the output port, that is, the phase change that the signal light receives Find the amount.

As shown in Non-Patent Document 2, in the structure similar to the arrayed waveguide grating of FIG. 2, the light propagated through the arrayed waveguide is condensed to one output port. It is necessary to satisfy the following equation in the first arrayed waveguide.

Where βs, βc _{, L} , βc, _NL are the propagation constants of the slab waveguide, array waveguide, and nonlinear medium waveguide, fj is the radius of curvature of the slab waveguide, lj is the array waveguide spacing, and xj is The distance from the center of the slab waveguide of the input / output port, λ ₀ is the wavelength of the signal light, Lc is the length of the arrayed waveguide, and ΔL is the length difference between adjacent arrayed waveguides of the nonlinear medium waveguide The length increases as the waveguide goes down the figure. The subscript j indicates 1 for the input side and 2 for the output side. The following formula is obtained by arranging the above formula.

Here, the above equation is differentiated by the pump light intensity P _pump , the change of the output port position due to the phase change is Δx _2, and the phase change amount in the nonlinear medium is expressed by ψ _NL , In order to switch the output port to another port due to the phase change, the following equation must be satisfied.

と設計して、スイッチングに必要な位相変化量を求めると下式になる。

Here, n _s is the refractive index of the slab waveguide. Where specifically

And the phase change amount required for switching is obtained as follows.

Here, if the number of arrayed waveguides is designed to be 16, the longest nonlinear medium waveguide requires a phase change amount of 0.135π as shown in the following equation.

Further, if the number of input / output ports of the switch is designed to be 8 × 8, when switching from the first port to the eighth port, a phase change amount of 0.95π is required as follows.

ここで、Aeffは非線形媒質の導波路の断面積である。 On the other hand, the change in the refractive index due to the optical Kerr effect and the maximum amount of phase change required in the waveguide of the nonlinear medium can be expressed by the following equation using the nonlinear refractive index n ₂ and the pump light intensity P _pump .

Here, Aeff is a cross-sectional area of the waveguide of the nonlinear medium.

Here, it is designed as a waveguide of a nonlinear medium made of semiconductor material AlGaAs. Non-Patent Document 3 shows that n ₂ = 3.8 × 10 ⁻¹³ cm ² / W. If the waveguide of the nonlinear medium is designed to have a width w = 1.5 μm, a thickness t = 0.1 μm, and P _pump = 3.5 W, Lmax = 831 μm and ΔL may be set to 52 μm, which is 1/16.

Therefore, switching requires P _pump = 3.5 W in each array waveguide, the pump light pulse width is set to 1.6 ps, the signal light pulse width is set to about 1.4 ps, and insertion loss from the input port to each nonlinear medium is reduced. If the design is 3 dB, switching is possible if the pump light intensity is 112 W at maximum. In order to output a pulse to the i-th port, it is only necessary to input the above (i-1) / 7 times pump light.

As described above, when the total number of arrayed waveguides is k, and the pump light power incident on each arrayed waveguide is P _pump , a nonlinear medium necessary for outputting signal light to a desired output port If the maximum length of the waveguide is Lmax, the length difference ΔL between adjacent nonlinear medium waveguides is
ΔL = Lmax / k
It can be seen that

  Finally, the signal light emitted from the output port and the remaining pump light are separated by, for example, a wavelength filter, and then the desired modulation format is obtained by a 3R regenerator capable of 3R regeneration (amplification, timing regeneration, waveform shaping). Thus, the optical signal can be spatially switched.

  Here, in order to reduce the optical insertion loss and to efficiently separate the signal light and the remaining pump light with the wavelength filter with the wavelength filter, the wavelength of the signal light and the pump light is the absorption edge wavelength of each waveguide and nonlinear medium. What is necessary is just to set longer and more than the transmission band of a wavelength filter. For example, if the nonlinear medium absorption edge wavelength is set to 1400 nm, the signal light wavelength is set to 1550 nm, the pump light wavelength is set to 1547 nm, and the transmission band of the wavelength filter is set to 3 nm around the transmission band, the signal light can be easily separated. .

  At this time, if the pulse width of the signal light is made narrower than that of the pump light so that the refractive index change occurs over the entire pulse width of the signal light, there is an advantage that the waveform distortion of the signal light is less likely to occur.

By using such a structure, the core part of the space optical switch, that is, the switch fabric part, can be composed of only passive optical circuits, so there are electric drive circuits with high power consumption and complicated wiring structures with high manufacturing costs. It becomes unnecessary.
In addition, since the wavelength conversion function is not used, a high-speed wavelength tunable laser or the like is not necessary, and expandability such as multi-ports is high. However, the number of ports must also take into account crosstalk at the output port, reception sensitivity of the 3R reproduction circuit, and the like.
Further, the number of ports can be increased by connecting the space optical switches in multiple stages.

[Example 2]
Next, an optical switch system 200 according to Embodiment 2 of the present invention will be described with reference to FIG.
The optical switch system 200 generates a switch fabric unit 100a having the same configuration as the switch fabric unit 100, which is the core part of the optical switch 10 shown in FIG. 1, and pump light and signal light input to the switch fabric unit 100a. It consists of parts.

  More specifically, the optical switch system 200 shown in FIG. 3 includes a switch fabric unit 100a having a plurality (11 in this example) of input ports 111a to 111k and 11 output ports (not shown), In the example, 11 light control circuits 210-1 to 210-11, a pump light mode-locked laser (Pump MLL) 221, a waveform shaper (Pump Pulse Shaper) 222, and a signal mode-locked laser (Signal MLL) ) 223, a signal shaper (Signal Pulse Shaper) 224, a first optical fiber circuit 231 that is a first branch / delay circuit having a branch / delay function, and a second branch / delay function having a branch / delay function. The second optical fiber circuit 232 is a delay circuit.

The mode pump light locked laser 221 and the waveform shaper 222, the first short pulse light source for generating a short pulsed light P _PS underlying the pumping light P _P is configured.
The signal mode-locked laser 223 and the waveform shaper 224 constitute a second short-pulse light source that generates the short-pulse light P _SS that is the basis of the signal light P _S.
The switch fabric unit 100a differs from the switch fabric unit 100 shown in FIG. 1 in the number of input / output ports, but the other configurations and switching functions are the same.

  Each of the optical control circuits 210-1 to 210-11 includes an optical attenuation selector 211, an all-optical gate 212, and an optical combiner 213. .

The pump light mode-locked laser 221 generates a short pulse light P _PS that is the basis of the pump light P _P. The generated short pulse light _PPS is shaped by the waveform shaper 222 as necessary. Waveform-shaped short pulse light _PPS is propagated and branched by the optical fiber circuit 231 and input (distributed) with different delay amounts to the optical attenuation selectors 211 of the optical control circuits 210-1 to 210-11. )

At this time, been propagated branched by an optical fiber circuit 231, the short-pulse light P _PS going is distributed to optical attenuation selector 211 of each optical control circuit 210-1～210-11 of each port, at least each port having a pulse width or interval of the short pulse light P _PS (time offset) between, and, when the pump light P _P generated on the basis of the short-pulse light P _PS of each port is input to the switch fabric unit 100a The circuit configuration of the optical fiber circuit 231 (the position of the branching portion, the fiber length that defines the delay amount, etc.) is adjusted so as not to overlap on the same time axis.

Pulsed light P _PS input to the optical control circuit 210-1～210-11 is the optical attenuation selector 211 is first branch, each pulsed light P _PS were branches then each packet length throughout is adjusted attenuated intensity is different, further one is selected from among the short-pulse light P _PS of the plurality of light intensity (attenuation intensity), the light coupling short optical pulses P _PS of one selected as the pumping light P _P To the device 213.
Different light intensities of the selected one of the pump light P _P from the attenuated intensity is adjusted a plurality of short optical pulses P _PS, as the light from a predetermined output port of the switch fabric portion 100a is output, the non-linear It is an intensity that generates a change in the refractive index of the medium.

The signal light mode-locked laser 223 is synchronized with the pump light mode-locked laser 221 and generates the short pulse light P _SS that is the basis of the signal light P _S. The short pulse light P _SS is synchronized with the short pulse light P _pS generated by the pump light mode-locked laser 221 and has a different wavelength.
The generated short pulse light P _SS is shaped by the waveform shaper 224 as necessary. The short-pulse light P _SS having the waveform shaped is propagated and branched by the optical fiber circuit 232, and is input (distributed) with different delay amounts to all the optical gates 212 of the optical control circuits 210-1 to 210-11. Is done.

At this time, the short pulse light P _SS propagated and branched by the optical fiber circuit 232 and distributed to all the optical gates 212 of the optical control circuits 210-1 to 210-11 of each port is at least between the ports. having a pulse width or interval of the short pulse light P _SS (time difference), and, the same time when signal light P _S generated on the basis of the short-pulse light P _SS of each port is input to the switch fabric unit 100a The circuit configuration of the optical fiber circuit 232 (position of the branching portion, fiber length that defines the delay amount, etc.) is adjusted so as not to overlap on the axis.

Therefore, the pump light P _P and the signal light P _{S at} each port overlap on the time axis, and do not overlap those at different ports.

Pulsed light P _SS is input to all-optical gate 212, with the control light P _C corresponding to the optical packet information, transmitted when the logic level is 1, attenuated when the logic level 0. Thus, the signal light P _S output from the all-optical gate 212 has light when the logic level is 1, and does not exist when the logic level is 0.

  As the all-optical gate 212, for example, cross absorption modulation (XAM) of an electroabsorption modulator may be used. Further, since the logic level can be inverted by the 3R circuit, the logic level may be inverted when the logic level is 0.

The pump light P _P and the signal light P _S are combined by the optical coupler 213 and input to the input ports 111a to 111k of the switch fabric unit 100a.

In the manner described in the above since the switching is performed in the switch fabric unit 100a, the signal light P _S of a desired packet is output from the desired output port.

As previously mentioned,
(1) short-pulse light P _PS going inputted to the optical attenuator selector 211 of each port has a pulse width or spacing of the short optical pulses P _PS between at least the port (time shift), and each port The circuit configuration of the optical fiber circuit 231 is adjusted so that the pump light P _P generated based on the short pulse light P _PS is not overlapped on the same time axis when input to the switch fabric unit 100a.
(2) The short pulse light P _SS input to the all-optical gate 212 of each port has at least an interval (time shift) equal to or greater than the pulse width of the short pulse light P _SS between the ports, The circuit configuration of the optical fiber circuit 232 is adjusted so that the signal light P _S generated based on the short pulse light P _SS does not overlap on the same time axis when input to the switch fabric unit 100a.
(3) Moreover, the pump light P _P and the signal light P _{S at} each port overlap on the time axis and do not overlap those at different ports.

Thereby, the packet information received simultaneously by the time division multiplexing method can be switched. For example, when the signal speed is 40 Gb / s (1 bit is 25 ps) and the short pulse width is 500 fs, if the short pulse interval between each port is 1 ps, 25 signals can be processed simultaneously without any adverse effects.
In other words, even if packets are input from a plurality of ports, the processing is performed by the time division multiplexing method without affecting each other.

  It is desirable that the nonlinear medium inserted into the arrayed waveguide of the switch fabric portion 100a has a large nonlinear effect and has a low manufacturing cost. Therefore, the material of the nonlinear medium may be a semiconductor such as AlGaAs, a dielectric material such as lithium niobate, or a material having a photonic crystal structure.

The above structure is desirably realized by a material with low manufacturing cost. Therefore, a quartz-based planar optical circuit, a semiconductor planar optical circuit, or a dielectric planar optical circuit may be used. Furthermore, they may be monolithically or hybridly integrated.
For example, an input slab waveguide, an output slab waveguide, an arrayed waveguide, and a nonlinear medium may be integrated in a silica-based planar lightwave circuit.
Further, the arrayed waveguide and the nonlinear medium may be monolithically integrated with semiconductor materials having different band gap wavelengths and waveguide structures.

DESCRIPTION OF SYMBOLS 10 Optical switch 100,100a Switch fabric part 110 Input slab waveguide 120 Output slab waveguide 130a-130k Array waveguide 131a-131k Nonlinear medium 140 3R regenerator 200 Optical switch system 210-1-210-11 Optical control circuit DESCRIPTION OF SYMBOLS 211 Optical attenuation selector 212 All-optical gate 213 Optical coupler 221 Pump light mode-locked laser 222 Waveform shaper 223 Signal light mode-locked laser 224 Waveform shaper 231 232 Optical fiber circuit which is a branch delay circuit

Claims (8)

An input slab waveguide that includes a plurality of input ports and a plurality of output ports, and outputs light from each of the output ports when light is input from any of the input ports. When,
The same number of input ports as the output ports of the input slab waveguide, and a plurality of output ports, and according to the relative phase difference of each light input to the input port, An slab waveguide for output in which one output port from which light is output is determined,
A plurality of arrayed waveguides adjacent to each other in the order in which the output port of the slab waveguide for input and the input port of the slab waveguide for output are individually connected;
Each time it is inserted into each of the arrayed waveguides, and the length of each of the arrayed waveguides is shifted from the adjacent one of the arrayed waveguides to the adjacent adjacent one of the arrayed waveguides, the length is sequentially constant. A long non-linear medium,
Have
The input light of the input slab waveguide is input with pump light and signal light having a wavelength different from that of the pump light and synchronized with the pump light.
One optical port from which the signal light is output is determined among a plurality of output ports of the output slab waveguide according to a change in refractive index of the nonlinear medium due to the pump light. In claim 1,
The optical switch characterized in that the pulse width of the signal light is narrower than the pulse width of the pump light. In claim 1 or claim 2,
Each of the output ports of the slab waveguide for output is provided with a wavelength filter that removes the pump light and transmits the signal light. In any one of Claims 1 thru | or 3,
The nonlinear medium is composed of lithium niobate;
An optical switch, wherein the input slab waveguide, the output slab waveguide, the arrayed waveguide, and the nonlinear medium are integrated in a quartz-based planar lightwave circuit. In any one of Claims 1 thru | or 3,
An optical switch characterized in that the arrayed waveguide and the nonlinear medium are monolithically integrated with semiconductor materials having different bandgap wavelengths and waveguide structures. In any one of Claims 1 thru | or 5,
An optical switch, wherein the nonlinear medium is composed of a photonic crystal. In any one of Claims 1 thru | or 6,
An optical switch, wherein a 3R regenerator is connected to each of the output ports of the output slab waveguide. An optical switch according to any one of claims 1 to 7,
A first short pulse light source that generates short pulse light for pump light;
A second short pulse light source that generates a short pulse light for signal light having a wavelength different from that of the short pulse light for pump light and synchronized with the short pulse light for pump light;
A plurality of optical control circuits having an optical attenuation selector, an all-optical gate, and an optical coupler, and sending light output from the optical coupler to an input port of the optical switch;
The short pulse light for the pump light generated from the first short pulse light source is branched and propagated to the plurality of optical attenuation selectors with different delay amounts of the branched short pulse light for the pump light. A first branch / delay circuit;
The short pulse light for signal light generated from the second short pulse light source is branched, the amount of delay of the branched short pulse light for signal light is made different, and the delay state is the first branch / delay A second branch / delay circuit that propagates to each of the plurality of all optical gates in the same manner as the delay state in the circuit,
Each of the optical attenuation selectors branches the short pulse light for the pump light propagated by the first branch / delay circuit into a plurality of parts, and has different attenuation intensity with respect to the branched short pulse light. Attenuate and output one of the branched and attenuated pulsed light as pump light,
Each of the all-optical gates transmits the short pulse light for signal light propagated by the second branch / delay circuit when there is control light corresponding to optical packet information inputted from the outside. Attenuate when there is no control light, and output as signal light,
Each of the optical couplers combines the pump light output from the optical attenuation selector and the signal light output from the all-optical gate synchronized with the pump light, and An optical switch system characterized by being sent to one of the input ports.

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