JPWO2014104038A1 - Wavelength converter - Google Patents

Abstract

The characteristics of the output waveform can be easily changed, and the frequency and wavelength are switched at high speed according to the input signal light with a simple configuration using an optical pulse generator that can obtain an accurate output waveform. Provided is a wavelength conversion device capable of this. The wavelength converter (90) is an optical pulse generator (12) that includes an optical pulse having a waveform including a constant or substantially constant gradient portion at least partially, and generates an optical pulse train having the same waveform of each optical pulse. ), A gradient control unit (14) that generates the control light PC by controlling the magnitude of the gradient of each optical pulse of the optical pulse train input from the optical pulse generator (12), the signal light PS and the control light A wavelength converter (16) for inputting the PC, shifting the center wavelength of each pulse of the signal light PS in accordance with the gradient of the control light PC, and making the wavelength of the signal light PS variable. It was configured as follows.

Description

  The present invention relates to a wavelength conversion device.

  In recent years, with an increase in transmission signal capacity in an optical transmission system, a WDM (Wavelength Division Multiplexing) communication system has been developed. When a WDM communication system is used as a network, it is required to perform wavelength conversion so that the wavelengths of signal lights from different paths do not overlap. In order to construct a flexible optical network, it is important that wavelength conversion be performed at high speed.

  One method of the high-speed wavelength conversion technique is to use cross phase modulation (XPM), which is a kind of nonlinear optical effect. Cross-phase modulation is a phenomenon in which when signal light and control light are incident on a nonlinear medium, a phase modulation amount proportional to the intensity of the control light is given to the signal light. Since the optical frequency is a differential of phase modulation, frequency shift (wavelength conversion) can be realized if the signal light is subjected to phase modulation with a constant inclination. The direction of the wavelength shift is determined by the intensity gradient of the control light, and the amount of spectrum shift (conversion wavelength width) is determined by the intensity gradient of the control light. As the nonlinear medium used in the present method, a highly nonlinear element such as a special glass fiber or a silicon fine wire waveguide can be widely used as a representative of a highly nonlinear fiber.

  As a specific method of wavelength conversion using the above-mentioned cross-phase modulation, there is a method of performing wavelength conversion via cross-phase modulation by superimposing signal light pulses and control light pulses in time and propagating them in a nonlinear medium. is there. As a conventional example of such a wavelength converter, there can be mentioned a conventional example 1 that uses a Gaussian pulse for the control light and a conventional example 2 that uses a sawtooth pulse for the control light.

FIG. 14 shows a wavelength converter 800 according to Conventional Example 1 disclosed in Non-Patent Document 1.
In FIG. 14A, a thick line indicates an optical fiber, and the wavelength conversion device 800 includes a highly nonlinear fiber 802, an optical filter 804, a first input port 810, a second input port 812, and an output port 814. It consists of Note that normal single mode fibers are used for the first input port 810, the second input port 812, and the output port 814.

In FIG. 14 (a), the wavelength lambda ₁ of the signal light P _S to a first input port _810, the second input port 812 receives the control light P _C Gaussian pulse type, the highly nonlinear by temporally superimposing By propagating through the fiber 802, the wavelength conversion device output light P _M (wavelength converted signal light P _S ) having the wavelength λ ₂ converted from the output port 814 can be obtained.

FIG. 14 (b) shows an example of a change in the waveform of the signal light P _S and the control light P _C in the time domain. As shown in the figure, causing cross phase modulation by the signal light P _S and the control light P _C so as to overlap the leading edge to propagate the highly nonlinear fiber 802 inside. Since providing a phase modulation slope signal light P _S in a rising portion of the control light P _C where the Gaussian waveform, it is possible to change the wavelength of the signal light P _S corresponding to the phase modulation amount. As a result, as shown in FIG. 14 (c) showing the change of the signal light P _S and the control light P _C in the frequency domain, the wavelength of the signal light input P _S is converted into lambda ₂ from lambda ₁ , The wavelength conversion device output light P _M (wavelength converted signal light P _S ).

FIG. 15 shows a wavelength converter 900 according to Conventional Example 2 disclosed in Non-Patent Document 2.
In FIG. 15A, a thick line indicates an optical fiber, and the wavelength converter 900 includes a highly nonlinear fiber 902, a first input port 910, a second input port 912, an output port 914, a circulator 916, and an SSFBG ( Super Structured Fiber Bragg Grating (918) 918 is comprised. Note that normal single mode fibers are used for the first input port 910, the second input port 912, and the output port 914.

Figure 15 (a), the type wavelength lambda ₁ of the signal light _{P S} to a first input port 910, the control light _{P C} is a sawtooth pulse generated in SSFBG918 to the second input port 912, the time By overlapping and propagating through the highly nonlinear fiber 902, the wavelength conversion device output light P _M (wavelength converted signal light P _S ) having the wavelength λ ₂ converted from the output port 914 can be obtained.

The SSFBG is an element in which FBG (Fiber Bragg Grating), which is an optical fiber type band reflection filter, is periodically arranged and the phase between them is adjusted. In the second conventional example, a predetermined optical pulse P _C ′ is incident on the SSFBG 918 from the second input port 912 to reflect and synthesize a frequency component necessary to form a sawtooth pulse, thereby forming a sawtooth shape. A pulse is generated.

FIG. 15B shows an example of a change in the waveform of each signal in the time domain. As shown in the figure, causing cross phase modulation by and so that the rising portion of the control light P _C to the signal light P _S overlap propagating highly nonlinear fiber 902 inside. Since providing a phase modulation on the slope of the rising portion of the control light P _C where the sawtooth waveform signal light P _S, it is possible to change the wavelength of the signal light P _S in accordance with the phase modulation amount. As a result, as shown in FIG. 15 (c) showing the change of the signal light P _S and the control light P _C in the frequency domain, the wavelength of the signal light input P _S is converted into lambda ₂ from lambda ₁ , The wavelength conversion device output light P _M (wavelength converted signal light P _S ).

Jianjun Yu; Jeppesen, P .;, 80-Gb / s wavelength conversion based on cross-phase modulation in high-nonlinearity dispersion-shifted fiber and optical filtering, Photonics Technology Letters, IEEE, Vol.13, No.8, 2001, pp.833-835 Parmigiani, F .; Ibsen, M .; Petropoulos, P .; & Richardson, DJ;, Efficient All-Optical Wavelength-Conversion Scheme Based on a Saw-Tooth Pulse Shaper, Photonics Technology Letters, IEEE, Vol.21, No. 24, 2009, p1837-p1839

However, for the conventional example 1, since the control light P _C is Gaussian pulse, the rising portion of the slope is constant time range Delta] t (Fig. 14 (b) refer) is narrow, and the control light P _C and the signal light P _S Strictness is required for the timing adjustment.
Further, in the conventional example 1, on which the optical filter 804 is required for cutting the converted signal light, also the conversion efficiency of the signal light P _S low. The reason will be described below.

As shown in FIG. 14 (c), of the light energy of the signal light P _S, the portion the inclination of the control light P _C did not enter the predetermined time width, frequency component different from the frequency of the converted light of interest because it is converted into the spectrum of the signal light P _S is enlarged. Therefore, in order to cut out the wavelength conversion device output light P _M of the wavelength lambda ₂ of interest, it is necessary to use a band-pass optical filter 804 having a center wavelength lambda _2.
At this time, since the spectrum other than the wavelength λ ₂ is removed, the conversion efficiency of the light energy becomes very low.

On the other hand, conventional example 2, the drawbacks of the conventional example 1 of slope is narrow constant time width of the control light P _C, it is improved by using the control light P _C of serration pulses. The inclination of the rising portion of the sawtooth pulses is constant its time width is wide, a margin is generated in the time alignment of the control light P _C and the signal light P _S. Further, since the slope of the sawtooth pulses are easy to pay a pulse of the signal light P _S to a certain time width, than only the wavelength shift without the spectrum is enlarged is produced, it is possible to increase the wavelength conversion efficiency it can.

However, since the conventional example 2 uses the SSFBG with fixed input / output characteristics, it is difficult to change the width and wavelength of the sawtooth pulse to an arbitrary value. Therefore, the gradient of the output sawtooth pulse is also fixed. Thus, for example, when the width and wavelength of the signal light P _S consisting of a pulse train is changed from the initial setting, it can not correspond to that. It is also not possible as the wavelength variable at each pulse unit signal light P _S.

  Furthermore, since SSFBG irradiates an optical fiber with ultraviolet interference fringes and a periodic refractive index change is formed in the optical fiber by the ultraviolet-induced refractive index change, the refractive index change can be precisely controlled. There is a drawback that the shape of the generated sawtooth pulse (particularly the linearity of the rising portion) is not accurate. If the linearity of the rising portion of the sawtooth pulse is poor, the wavelength of the signal light cannot be accurately shifted, as in the case of the Gaussian pulse of the conventional example 1.

  The present invention has been made in view of the background as described above, and can generate an optical pulse train having a certain gradient, and can switch the wavelength of input signal light by adjusting the intensity thereof. An object of the present invention is to provide a simple wavelength conversion device.

  The wavelength conversion device according to the first aspect of the present invention is a device that converts the wavelength of the signal light pulse train by temporally superposing and inputting the signal light pulse train and the control light pulse train. An optical pulse generator that generates an optical pulse train having an optical pulse having a waveform including a substantially constant gradient portion, and each of the optical pulse trains input from the optical pulse generator. A gradient control device that generates a control light pulse train by controlling the magnitude of the gradient of the optical pulse, a signal light pulse train and the control light pulse train, and inputs signal light according to the slope magnitude of the control light pulse train And a wavelength converter that shifts the center wavelength of each pulse of the pulse train and makes the wavelength of the signal light pulse train variable.

  A wavelength conversion device according to a second aspect of the present invention is the wavelength conversion device according to the first aspect, wherein the signal light pulse train is an optical signal obtained by time-division multiplexing optical signals of a plurality of channels. A controller that determines a wavelength to be converted and controls the gradient controller so that a control optical pulse train having a gradient according to the shift amount of the wavelength and having the number of channels as a period is generated; And the wavelength converter converts the wavelength of the signal light pulse train with a different shift amount for each channel and outputs the converted signal as an output optical signal.

  A wavelength conversion device according to a third aspect of the present invention is the wavelength conversion device according to the second aspect, wherein a detection device that detects a head position of the signal light pulse train, and the signal light pulse train that is input from the detection device. And a variable delay device that delays at least one of the control light pulse trains input from the gradient control device and adjusts a time difference between the head position of the signal light pulse train and the head position of the control light pulse train, The control device adjusts the time difference by controlling the variable delay device so that a temporal overlap between the signal light pulse train and the control light pulse train causes wavelength conversion in the wavelength converter.

  A wavelength conversion device according to a fourth aspect of the present invention is the wavelength conversion device according to the second aspect or the third aspect, wherein an input terminal for inputting the output optical signal output from the wavelength conversion unit, It further includes a spectroscopic element having a plurality of output terminals for separating and outputting the channel included in the output optical signal according to the wavelength.

  The wavelength conversion device according to a fifth aspect of the present invention is the wavelength conversion device according to the fourth aspect, wherein the plurality of output ends are connected to different transmission destinations, and the control device Along with the change, the gradient control device is controlled so that the output end from which the optical signal of the channel is output becomes the output end connected to the changed transmission destination, and the control optical pulse train corresponding to the channel is controlled. The gradient of each light pulse is changed to a gradient corresponding to the wavelength corresponding to the changed output end.

  A wavelength conversion device according to a sixth aspect of the present invention is the wavelength conversion device according to the first aspect, wherein the signal light pulse train is an optical signal composed of a plurality of packets arranged in time series. The gradient control is performed so that a wavelength to be converted is determined, and a control optical pulse train having a gradient according to the shift amount of the wavelength and having a period of the number of bits included in the packet is generated for each packet. A second control device for controlling the device is further included, and the wavelength conversion unit converts the wavelength of the signal light pulse train with a shift amount different for each packet and outputs it as an output optical signal.

  A wavelength conversion device according to a seventh aspect of the present invention is the wavelength conversion device according to the sixth aspect, wherein a detection device that detects a head position of each packet and the signal light pulse train input from the detection device And a variable delay device that delays at least one of the control light pulse trains input from the gradient control device and adjusts a time difference between the head position of the signal light pulse train and the head position of the control light pulse train, The second control device adjusts the time difference by controlling the variable delay device such that a time overlap between the signal light pulse train and the control light pulse train causes wavelength conversion in the wavelength converter. Is.

  A wavelength conversion device according to an eighth aspect of the present invention is the wavelength conversion device according to the sixth aspect or the seventh aspect, wherein an input terminal for inputting the output optical signal output from the wavelength conversion unit, It further includes a spectroscopic element having a plurality of output terminals for separating and outputting the packet included in the output optical signal according to the wavelength.

  A wavelength conversion device according to a ninth aspect of the present invention is the wavelength conversion device according to the eighth aspect, wherein the plurality of output ends are connected to different transmission destinations, and the second control device With the change of the transmission destination, the gradient control device is controlled so that the output end from which the optical signal of the packet is output becomes the output end connected to the changed transmission destination, and the control corresponding to the packet The gradient of each optical pulse in the optical pulse train is changed to a gradient corresponding to the wavelength corresponding to the changed output end.

  The wavelength conversion device according to a tenth aspect of the present invention is the wavelength conversion device according to any one of the first to ninth aspects, wherein the waveform of each optical pulse of the control light pulse train includes a rising portion and a falling portion. At least one of the parts has a waveform having a constant or substantially constant gradient.

  The wavelength conversion device according to an eleventh aspect of the present invention is the wavelength conversion device according to any one of the first to tenth aspects, wherein the waveform of each optical pulse of the control light pulse train is constant at the rising portion or The sawtooth waveform has a substantially constant gradient and the falling portion quickly falls, or the sawtooth waveform has a constant or substantially constant gradient in the falling portion and the rising portion quickly rises.

  A wavelength conversion device according to a twelfth aspect of the present invention is the wavelength conversion device according to any one of the first to eleventh aspects, wherein the gradient control device includes each optical pulse included in the input optical pulse train. Is controlled to control the magnitude of the gradient.

  A wavelength conversion device according to a thirteenth aspect of the present invention is the wavelength conversion device according to any one of the first to twelfth aspects, wherein the wavelength conversion unit uses a nonlinear optical element including a nonlinear fiber or a nonlinear optical crystal. Configured.

  A wavelength converter according to a fourteenth aspect of the present invention is the wavelength converter according to any one of the first to thirteenth aspects, wherein the optical pulse generator branches a part of the output, and an optical spectrum analyzer. Is an optical pulse synthesizer that generates an optical pulse train having the same pulse waveform by feeding back and controlling the optical spectrum measured via the optical waveform and the pulse waveform measured via the optical sampling oscilloscope. .

  A wavelength converter according to a fifteenth aspect of the present invention is the wavelength converter according to any one of the first to fourteenth aspects, wherein the optical pulse generator is a pulse light source, and light input from the pulse light source. A first optical pulse shaper that generates and outputs an optical pulse having a waveform including a constant or substantially constant positive gradient portion by controlling the intensity and phase of the pulse; the intensity of the optical pulse input from the pulse light source; A second optical pulse shaper that generates and outputs an optical pulse having a waveform including a constant or substantially constant negative gradient portion by controlling the phase; and an output of the first optical pulse shaper and the second And an optical switch that selects one of the outputs of the optical pulse shaper and outputs it as an optical pulse train having the same waveform.

  ADVANTAGE OF THE INVENTION According to this invention, the wavelength converter which can generate | occur | produce the optical pulse train which has a fixed gradient, and can switch the wavelength of input signal light by adjusting the intensity | strength can be provided.

It is a block diagram which shows the structural example of the wavelength converter which concerns on 1st Embodiment. It is a wave form diagram which shows the actual value and target value of the waveform of the control light of the wavelength converter which concerns on an Example. It is a schematic diagram of each part waveform etc. for demonstrating the spectrum of each waveform of the wavelength converter which concerns on an Example, and wavelength conversion operation | movement. It is a graph which shows the wavelength conversion width with respect to the input power of the wavelength converter which concerns on an Example. It is a figure which shows the optical spectrum of the output of the wavelength conversion part by the presence or absence of wavelength conversion of the wavelength converter which concerns on an Example. It is a wave form diagram which shows the waveform of the control light with respect to the fixed pattern of the wavelength converter which concerns on an Example, and the converted light. It is a block diagram which shows the structural example of the wavelength converter which concerns on 2nd Embodiment. It is a schematic diagram which shows the waveform of the sawtooth pulse generated with the optical pulse generator which concerns on 2nd Embodiment. It is a block diagram which shows the structural example of the optical pulse generator which concerns on 2nd Embodiment. It is a schematic diagram which shows the waveform of each part of the wavelength converter which concerns on 2nd Embodiment. It is a block diagram which shows the structural example of the wavelength converter which concerns on 3rd Embodiment. It is a schematic diagram which shows the structure of the packet which concerns on 3rd Embodiment. It is a block diagram which shows the structural example of the wavelength converter which concerns on 4th Embodiment. It is a schematic diagram for demonstrating the wavelength converter by the prior art example 1. FIG. It is a schematic diagram for demonstrating the wavelength converter by the prior art example 2. FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 shows a wavelength converter 90 according to the present embodiment. The wavelength converter 90 includes an optical pulse generator 12, a gradient controller 14, a wavelength converter 16, an optical filter 64, a first input port 66, a second input port 67, and an output port 68. Yes.

  The optical pulse generator 12 is a part that generates an optical pulse of constant intensity having a constant or substantially constant gradient portion in the waveform, and can be configured by, for example, an optical pulse synthesizer as described later. In the present embodiment, the constant intensity light pulse is a pulse having a constant intensity sawtooth waveform as shown in FIG. By using the optical pulse synthesizer, the wavelength and width of the sawtooth waveform pulse can be easily changed, and an optical pulse generator that generates an accurate control light waveform can be configured.

（ここで、Ｔはゼロレベル幅であり、光強度が０の位置の光パルスの時間幅をいう）
なので、ピーク強度Ｐ_ｈを変えることによって、パルスの勾配を制御できる。
なお本実施の形態における制御光Ｐ_Ｃの波形は、一定または略一定の勾配部分を有する波形であれば、特に鋸歯状波形に限定されることなく適用することができる。The gradient control unit 14 controls the gradient of the optical pulse by changing the peak intensity (P _h in FIG. 8) of the optical pulse input from the optical pulse generator 12 based on, for example, an external signal. is a portion for generating the control light P _C. For example, the gradient control unit 14 can be configured by an optical amplifier, an optical modulator (optical attenuator), or the like. 8, when the gradient of the pulse and P _O,

(Here, T is the zero level width, and the time width of the optical pulse at the position where the light intensity is 0)
So, by changing the peak intensity P _h, it can be controlled gradient pulse.
Note waveforms of the control light P _C in the present embodiment, if a waveform having a constant or substantially constant gradient section, can be applied without being limited to the sawtooth waveform.

Wavelength converter 16, the inclination performs constant intensity modulated signal light P _S using constant or nearly constant slope portion of the control light P _C, it is sites for performing frequency shift (wavelength conversion) into signal light P _S For example, it can be configured using a nonlinear fiber, a nonlinear optical crystal, or the like. In the present embodiment, the wavelength conversion method will be described by exemplifying a form using cross-phase modulation. However, the present invention is not limited to this, and if the control light having a constant or substantially constant gradient is used, It can be used without limitation.

ここで、γ：非線形光学素子の非線形定数、Ｐ_０：制御光のパルス強度の勾配、Ｌ：作用長
したがって、本発明では、非線形光学素子の上記特性を用いることにより、波長変換部１６を構成することができる。That is, in general nonlinear optical elements, the frequency shift amount Δf or the wavelength shift amount Δλ when control light having a constant or substantially constant gradient is incident on the nonlinear optical element is expressed by the following equation.

Where γ: nonlinear constant of the nonlinear optical element, P ₀ : gradient of pulse intensity of the control light, L: action length Therefore, in the present invention, the wavelength conversion unit 16 is configured by using the above characteristics of the nonlinear optical element. can do.

From the first input port 66 of the wavelength converter 90, the pulsed signal light P _S of wavelength λ _S1 is aligned, and from the second input port 67 the control light P _C of wavelength λ _C is aligned. Is input. 1, the wavelength of the signal light P _S is converted from λ _S1 to λ _S2 in the wavelength converter 16 and the wavelength conversion device output light P _M is output from the output port 68 as shown in the wavelength graph of FIG. Is output.

Here, the signal light pulse P _S and the wavelength converter output light pulse P _M have a constant spectral distribution. In the following description, the center wavelengths λ _S1 and λ _S2 of each pulse are simply described as wavelengths. .

Although the optical filter 64 in FIG. 1 is a filter for removing the control light P _C, in the present embodiment, may be provided as required, for example, the relationship between the wavelength converted signal light P _S In the following embodiments, this will be described in a form omitted.

As described above, the wavelength converter 90 according to the present embodiment employs the optical pulse generator 12 that generates a constant intensity optical pulse having a constant or substantially constant gradient portion in the waveform. Then, further to the subsequent stage, the optical pulse generator 12 can be controlled independently gradient of the light pulse by varying the intensity of the input optical pulse to generate a control light P _C from the gradient control unit 14 It is set as the structure which arranges.
Therefore, according to the wavelength conversion device according to the present embodiment, it is possible to generate an optical pulse train having a constant gradient, and to adjust the intensity, the wavelength conversion capable of switching the wavelength of the input signal light An apparatus can be provided.

[Example]
Examples of the wavelength conversion device according to this embodiment will be described below. In the present embodiment, the wavelength converter 90 shown in FIG. 1 is actually realized, and the following data is acquired.

  FIG. 2 shows a waveform of an asymmetric sawtooth optical pulse used as control light output from the optical pulse generator 12 of the wavelength converter 90. As described above, the optical pulse generator 12 is composed of an optical pulse synthesizer described later. The waveform shown by experimental values in FIG. 2 is an optical pulse having a repetition frequency of 10 GHz and a pulse width of 10 ps (half width, FWHM), and the output of the optical pulse generator 12 is observed.

  In the waveform shown in FIG. 2, the zero level width is 20 ps. Further, the waveform shown as the experimental value is a waveform observed in an actual wavelength converter, and the waveform shown as the target value is an ideal sawtooth pulse waveform obtained by simulation.

  In the sawtooth optical pulse waveform shown in FIG. 2 (a), the ratio of rise and fall is 1: 2, so the rise time is 6.7 ps (peak peak value, peak-to-peak value), and fall time. The time (peak peak value, peak-to-peak value) is 13.3 ps. FIG. 2B shows an optical pulse waveform in which the optical pulse waveform shown in FIG. Therefore, the ratio of rise and fall of the optical pulse waveform shown in FIG. 2B is 2: 1, the rise time is 13.3 ps, and the fall time is 6.7 ps.

As shown in FIGS. 2A and 2B, it can be seen that the experimental value and the target value are in good agreement. Therefore, according to the wavelength conversion device according to this embodiment, as an example, it is possible to generate the control light P _C with accurate sawtooth pulse waveform further rise time, fall time, i.e. serrated It is possible to flexibly cope with the setting of the gradient of the pulse waveform.

Next, the results of the wavelength conversion width will be described.
As previously described, in the wavelength conversion device according to this embodiment, by performing intensity modulation on the control light P _C signal light P _S with a gradient portion of, to obtain a wavelength shift amount Δλ proportional to the gradient it can. The wavelength conversion width here refers to the wavelength shift amount [Delta] [lambda], the wavelength and the wavelength conversion device output light pulse of the signal light P _S (hereinafter sometimes referred to as "converted light") by the difference between the wavelength of the P _M is there. In the present embodiment, the wavelength of the control light P _C, the signal light P _S, and the converted light P _M is the wavelength read by the peak value of the optical spectrum.

In this embodiment, the signal light P _S input from the first input port 66 of the wavelength conversion device 90 is a continuous light having a wavelength of 1540 nm, the output from the optical pulse generator 12 (i.e. control light P _C) 2 ( It was set as the optical pulse of wavelength 1550nm which has the sawtooth waveform shown to a). The wavelength converter 16 is a highly nonlinear fiber having a length of 100 m.

FIG. 3A shows an optical spectrum observed at the output of the wavelength converter 16 in the wavelength converter 90 shown in FIG. In the figure, the light spectrum centered wavelength 1550nm is control light _{P C,} line spectrum of wavelength 1540nm is the signal light _{P S.}

Further, the optical spectrum occurring on either side of the signal light P _S is the optical spectrum of the converted light P _M. Converted light P _M that is generated in the longer wavelength side with respect to the signal light P _S is the converted light P _M generated in response to the positive slope of the control light P _C, it is converted light called red shift. Further, a converted light P _M is converted light P _M that is generated in the short wavelength side of the signal light P _S generated in response to a negative slope of the control light P _C, the conversion light called blue shift is there.

Spectrum of the converted light P _M to the short wavelength side and the long wavelength side of the above, the optical spectrum of a rectangular wave having a fall time 13.3Ps, and the corresponding optical frequency rise time 6.7ps respectively control light P _C It is in good agreement with (sinc function shape). Therefore, it can be seen that wavelength conversion by mutual phase modulation is realized according to the principle.

FIGS. 3B to 3F are schematic diagrams for explaining the operation of the wavelength converter according to the present embodiment.
3 (b) is a waveform of a continuous optical signal beam P _S, FIG. 3 (c) shows the waveform of the control light P _C having the waveform shown in FIG. 2 (a). In the figure, t on the horizontal axis represents time, and P on the vertical axis represents optical power.

Further, FIG. 3 (d), corresponding to each of the leading edge and trailing edge of the control light P _C shown in FIG. 3 (c), shows the variation of the optical frequency f of the converted light P _M with respect to time. As shown in the figure, and (red shift was shifted to the negative side with respect to the optical frequency f (the frequency corresponding to 1540nm, which is the wavelength of the signal light P _S) to be a reference in the rising portion of the control light P _C ) it has become a constant has a light frequency, and (blue-shifted and shifted to the positive side with respect to optical frequency f as a reference in the falling portion of the control light P _C) constant light frequency.

Further, FIG. 3 (e) is a waveform of the converted light corresponding to the falling portion of the control light P _C, FIG. 3 (f) shows a waveform of the converted light corresponding to the rising portion of the control light P _C. FIGS. 2 (a) in the control light P _C having the waveform shown for cutting out part of the signal light P _S is continuous light temporally, each converted light having a waveform corresponding to the rising portion and falling portion of the control light P _C Becomes a rectangular wave as shown in FIGS. 3 (e) and 3 (f).

Here, as described above, the wavelength conversion width is proportional to the gradient of the temporal waveform of the intensity of the control light P _C (differential value of the time waveform of the intensity). In other words, the wavelength conversion width is proportional to the intensity gradient of the control light P _C, positive or negative by the wavelength conversion direction the respective said intensity gradient + direction, - direction (direction of the frequency shift, respectively - direction, + direction) and a. Thus, the wavelength conversion device according to this embodiment, by changing the peak intensity of the control light P _C having a sawtooth waveform shown in FIG. 2, it is possible to adjust the conversion wavelength of the converted light P _M.

4, when the wavelength is input and the signal light _{P S} of the continuous light and a control light _{P C} having a sawtooth waveform shown in FIG. 2 wavelengths 1550nm wavelength conversion unit 16 at 1540 nm, of the control light _{P C} The wavelength conversion width with respect to the light intensity (denoted as “input power” in the figure) is shown. 4A shows the wavelength conversion width of red shift and blue shift when the length of the highly nonlinear fiber constituting the wavelength conversion unit 16 is 100 m, and FIG. 4B shows the wavelength conversion unit 16. The wavelength conversion width of blue shift when the length of the highly nonlinear fiber is 200 m is shown. Although the input power in FIG. 4 shows the average value, the control light P _C according to this embodiment, since the zero level width is constant in the optical pulse waveform 20ps as shown in FIG. 2, a change in the input power of the control light P _C is that is a change in the peak intensity of the control light P _C.

As shown in FIG. 4A, when the length of the highly nonlinear fiber is 100 m, a wavelength conversion width of about 4 nm is realized by red shift, and a wavelength conversion width of about 3 nm is realized by blue shift. As shown in FIG. 4B, when the length of the highly nonlinear fiber is 200 m, a wavelength conversion width of about 6 nm is realized by blue shift. Therefore, according to the wavelength conversion device according to the present embodiment, the length of the highly nonlinear fiber, by adjusting the input power of the control light P _C, having a wavelength conversion width of more than 10nm combined red shift and blue shift It is possible to configure a wavelength converter.

Further, from FIG. 4, as an equation for calculating a wavelength shift amount Δλ indicated above, the input power of the wavelength conversion width control light P _C, i.e., in the present embodiment to the gradient of the pulse intensity of the control light P _C It can be seen that there is a proportional change. In addition, the slope of the interpolated straight line when the length of the highly nonlinear fiber shown in FIG. 4B is 200 m is the straight line interpolated when the length of the highly nonlinear fiber shown in FIG. 4A is 100 m. It can be seen that it is about twice the slope of. That is, it can be seen from the results of FIG. 4 that the wavelength converter according to the present example operates as theoretically.

Next, the wavelength conversion efficiency of the wavelength conversion device according to this embodiment will be described below.
The wavelength conversion efficiency, a ratio of light intensity in the case of not performing wavelength conversion of light intensity when performing when observed at the output of the wavelength converter 16, wavelength conversion to the signal light P _S, the wavelength conversion Is an index indicating how much light loss (or amplification) has occurred.

5, the output of the wavelength converter 16 cut by the optical filter 64, (in the figure, "there Wavelength conversion" hereinafter) when subjected to wavelength conversion and optical spectrum of the converted light P _M of, if not done (in the figure, labeled "No wavelength conversion") shows the optical spectrum of the signal light P _S of. In Figure 5, uses a pulse train of the pulse width of about 5.5ps the signal light P _S, the control light P _C is conditions wavelength conversion on the short wavelength side, i.e., the negative slope portion of the optical pulse of the sawtooth waveform The condition is to use. Also, stops the operation of the optical pulse generator 12 in the case without wavelength conversion, are not input control light P _C to the wavelength converter 16.

Further, in FIG. 5, to match the losses with and without wavelength conversion, if no wavelength conversion by the optical bandpass filter having a center wavelength a wavelength 1540nm signal light P _S, conversion in the case of Yes wavelength conversion wavelength of light _{P M 1538.5nm} (i.e., the result of the wavelength conversion, the signal light _P wavelength of _S are 1.5nm shifted to the short wavelength side) of the wavelength converter 16 by the optical bandpass filter having a center wavelength of Cutting out the output.

From FIG. 5, it can be seen that the peak value of the light intensity is greater in the case of wavelength conversion than in the case of no wavelength conversion. Further, the average light intensity without wavelength conversion is −3.3 dBm, the average light intensity with wavelength conversion is −1.6 dBm, and the wavelength conversion efficiency is 150% exceeding 100%. I understood it. Therefore, in the highly nonlinear fiber, the wavelength conversion by cross phase modulation and have occurred parametric amplification at the same time, it was found to be possible amplification of accordance when the signal light P _S in the wavelength converter.

  By the way, in the wavelength conversion device, not only the accurate conversion to a predetermined wavelength, but also the time required to convert the wavelength (wavelength switching time) is important. A result of confirming the wavelength switching time indicating the speed of the wavelength switch will be described with reference to FIG.

In the measurement of the wavelength conversion efficiency for each of the signal light optical pulse P _S of repetition frequency 10 GHz, it was allowed to act control light P _C which is a light pulse of the same intensity. Here, in order to confirm the switching time of the wavelength conversion operation, subjected to intensity modulation with the control light P _C by the gradient controller 14 shown in FIG. 1, the bit of the control light P _C the optical power signal light P _S per bit each corresponding to thereby varied, it was wavelength conversion for each bit of the signal light P _S.

At that time, the signal light P _S, and the control light P _C using two kinds of patterns of the fixed pattern 1101 and the fixed pattern 1000 as a pulse pattern, using a light band-pass filter as the optical filter 64 the output of wavelength converter 16 cut was observed waveforms of the converted light P _M corresponding to the fixed pattern. 6 shows the observation results, the waveform and the waveform of the converted light _{P M} of the control light _{P C} in the case of FIG. 6 (a) and (b) are each fixed pattern 1101, and FIG. 6 (c) ( d) show respectively waveforms and waveform of the converted light _{P M} of the control light _{P C} in the case of the fixed pattern 1000.

As shown in FIG. 6, the signal light P _C is a pulse train of 100ps intervals are extracted by the control light P _C of the two fixed pattern of different pulse patterns. From this, it can be seen that the wavelength conversion device according to the present example has a wavelength switching speed of 100 ps or less. This wavelength switching speed is a speed applicable not only to the wavelength conversion apparatus according to the present embodiment but also to a wavelength division multiplexing transmission apparatus or wavelength division packet transmission apparatus described later.

[Second Embodiment]
FIG. 7 shows the wavelength conversion device 10 according to the present embodiment. Wavelength converter 10 is time division multiplexed in a single optical (Optical Time Division Multiplex: OTDM) has been input signal light _{P S,} is a device that converts a wavelength converter output light _{P M} that is wavelength division multiplexing. The wavelength conversion device 10 converts the control light into a sawtooth pulse and performs wavelength conversion by cross phase modulation.

In the present embodiment, the wavelength to the input signal light P _S will be described by way of example a form of applying a certain single light, the present invention is not limited to this, each optical pulse wavelengths different signal light, for example, it is possible to similarly apply the input signal light P _S which is wavelength division multiplexing.

  As shown in FIG. 7, the wavelength converter 10 includes a wavelength converter 16, an optical pulse generator 12, a gradient controller 14, a variable delay device 20, a synchronization signal detector 24, a wavelength converter controller 18, and an optical coupler. 22 is comprised. A control light generation unit 30 is configured including the optical pulse generator 12, the gradient control unit 14, and the variable delay unit 20.

Synchronization signal detection unit 24, the division multiplexed signal light P _S when input to the wavelength converter 10 from the transmission line is required in performing wavelength conversion various synchronization signals S _S, i.e. time-division multiplexed signal The number of multiplexed signals, the position of the first bit, the clock frequency, etc. are detected. Synchronization signal detection unit 24, for example, an optical signal is once converted into an electric signal, after extracting a sync signal S _S is treated with an electronic circuit, be constituted by using a known circuit that converts again the optical signal it can. The detected synchronization signal S _S is sent to the wavelength converter control unit 18. In this embodiment, as an example, the multiplexing number is 4, and the channels of the time division multiplexed signal are four channels ch1, ch2, sh3, and ch4.

  The optical pulse generator 12 in the control light generator 30 is a device that generates a pulse having a sawtooth waveform with a constant intensity as shown in FIG. 8, and can be composed of, for example, an optical pulse synthesizer.

FIG. 9 shows a configuration example of the optical pulse generator 12 according to the present embodiment.
The optical pulse generator 12 shown in FIG. 9A includes a pulse laser 70 and an optical pulse shaper 72. The pulse laser 70 is a pulse light source for shaping into a control light pulse having a sawtooth waveform in the optical pulse shaper 72 at the next stage.

  The optical pulse shaper 72 receives an optical pulse and synthesizes an optical pulse of an arbitrary shape by independently adjusting the intensity and phase of each frequency component of the optical pulse. Since the frequency spectrum and the time waveform are in a two-sided relationship connected by Fourier transform, the time waveform can be synthesized into an arbitrary shape by adjusting the optical spectrum.

The optical pulse shaper 72 includes an optical spectrum analyzer and an optical sampling oscilloscope (or autocorrelator) (not shown). For intensity and phase control, a part of the optical output is split into an ideal sawtooth pulse shape based on the optical spectrum measured by the optical spectrum analyzer and the pulse waveform from the optical sampling oscilloscope. Feedback control is performed so that Control pulse synthesized in the optical pulse shaper 72 is output as an optical pulse generator output light P _P.

FIG. 9B shows another configuration example of the optical pulse generator 12 according to the present embodiment.
The optical pulse generator 12 shown in the figure includes a single frequency laser 74, an optical comb generator 76, a signal generator 78, and an optical pulse shaper 72. The optical pulse generator 12 shown in FIG. In this configuration example, an optical comb generator 76 is used instead of the pulse laser 70 in the pulse generator 12.

The optical comb generator 76 generates an optical frequency comb by phase-modulating the optical pulse input from the single frequency laser 74 with a phase modulator made of, for example, lithium niobate (LN). The signal generator 78 generates a microwave signal for driving the phase modulator. The frequency interval of the optical frequency comb and the repetition frequency of the generated optical pulse train are equal to the frequency of the microwave signal generated by the signal generator 78. Control pulse synthesized in the optical pulse shaper 72 is output as an optical pulse generator output light P _P. If a frequency variable laser is used as the single frequency laser 74, the center wavelength of the optical frequency comb can be selected.

Further, as shown in FIGS. 9A and 9B, the optical pulse shaper 72 has an input unit to which the frequency control signal CS ₁ is input, and based on the frequency control signal CS ₁ . The frequency of the control light pulse to be generated can be changed.

Here, with reference to FIG.9 (c), the structure which switches the positive / negative of the inclination of a gradient in the optical pulse generator 12 is demonstrated.
Since the optical pulse generator 12 can generate an optical pulse having an arbitrary shape, for example, an optical pulse (for example, an optical pulse shown in FIG. It is possible to change the direction of the wavelength shift with respect to the wavelength of the input signal light by switching the optical pulse shown in FIG.

However, since high-speed wavelength switching is required in an optical network, it is required to surely switch the conversion wavelength including the wavelength shift direction. The optical pulse generator 80 shown in FIG. 9C is configured in consideration of this point.
The optical pulse generator 80 includes an optical pulse shaper 72A that generates a sawtooth pulse having a positive slope, an optical pulse shaper 72B that generates a sawtooth pulse having a negative slope, a pulse laser 70, and 2 × 1 light. A switch 82 is included.

In FIG. 9C, the optical pulse shaper 72A and the optical pulse shaper 72B are operated in parallel in synchronization. Then, depending on the direction of the wavelength shift, by controlling the 2 × 1 optical switch 82, by the optical pulse generator output light P _P by switching the output of the optical pulse shaper 72A or the optical pulse shaper 72B Thus, it is possible to quickly switch between positive and negative slopes of the sawtooth pulse. The switching signal of the optical pulse shaper 72A and the optical pulse shaper 72B can be included in, for example, the CS ₁ that transmits the frequency control signal. According to the optical pulse generator 80, even if signal light having different wavelength shift directions in units of bits is mixed in the input signal light, for example, wavelength conversion can be performed without generating conversion loss.

  According to the optical pulse generator 12 configured as described above, it is possible to generate a control light pulse whose waveform is precisely controlled.

The gradient controller 14 in the control light generator 30 controls the gradient by changing the intensity of the sawtooth pulse. As described above, the shift amount of the frequency magnitude by the signal light P _S of the slope of the control light, that is, possible to control the conversion wavelength range, each channel included in the time-division multiplexed signal light P _S This configuration On the other hand, wavelength conversion in bit units can be performed. The gradient control unit 14 may be configured by an optical amplifier, an optical modulator (optical attenuator), or the like.

Variable delay unit 20 in the control light generator 30, in order to match the timing of the sequence of control light P _C which are controlled sequence and the gradient of the channel of the signal light P _S, required for control light P _C delay give. As a result, the wavelength is assigned to each channel of the signal light P _S, and the signal light P _S and the control light P _C are multiplexed by the optical coupler 22 in a state in which timing is combined, and the wavelength conversion unit 16 Led.

Wavelength converter 16 converts the wavelength by cross phase modulation on the basis of the combined signal light P _S and the control light P _C, a portion for output from the output port 146 as the wavelength conversion device output light P _M, the In the embodiment, a highly nonlinear fiber is employed.

Wavelength converter control unit 18 in accordance with the synchronization signal S _S received from the synchronization signal detector 24, controls the control light generator 30.

First, the clock frequency of the signal light P _S included in the synchronization signal S _S is sent to the optical pulse generator 12 as the frequency control signal CS ₁ .
Optical pulse generator 12, received on the basis of the frequency control signal CS _1, the control unit provided in the optical pulse shaper 72 determines the frequency of the sawtooth pulses (not shown) is generated, the intensity constant serrated pulse train Is generated.

The wavelength conversion device controller 18, in consideration of the wavelength or the like which is allowed to multiplex number and wavelength converter output light P _M included in the synchronization signal S _S, the wavelength allocation assigned to each channel of the signal light P _S determined, sent to the gradient controller 14 as a wavelength control signal CS _2.
The gradient control unit 14 determines the strength of the serrated pulse corresponding to the wavelength of each channel on the basis of the wavelength control signal CS ₂ received. Based on the determined strength, against a serrated pulse train having a constant intensity input from the optical pulse generator 12 to the gradient controller 14 optical pulse generator output light P _P, each serrated pulse corresponding to each channel Change strength. As a result, the control light P _C for varying the wavelength corresponding to each channel of the signal light P _S is obtained. In the present embodiment, as an example, since the number of multiplexing is 4, four conversion wavelengths λ ₁ , λ ₂ , λ ₃ , and λ ₄ are determined corresponding to ch1 to ch4.

Further, the wavelength converter control unit 18 calculates the time difference between the leading bit position of the pulse train of the control light P _C first bit position and generated by the signal light P _S included in the synchronization signal S _S, the required delay seek time, sent to the variable delay unit 20 as the delay time control signal CS _3.
Variable delay 20 delays the control light P _C on the basis of the delay time control signal CS ₃ received a delay control light P _D and. As a result, it is possible to adjust the timing of the signal light P _S and the control light P _C.
As the variable delay device 20, a known device such as a method of selecting transmission lines having different optical path lengths according to the delay time (for example, disclosed in Japanese Patent Application Laid-Open No. 08-220343) is used. it can.

Here, in the present embodiment has been described by way of example the form of delays the control light P _C timing the signal light P _S and the control light P _C, performed which delays the signal light P _S it may be, or both of the control light P _C and the signal light P _S may be performed with a delay. If delaying the signal light P _S may be arranged to variable delay 20 in the subsequent stage of the synchronization signal detector 24.

  Next, with reference to FIG. 10, each part waveform of the wavelength conversion device 10 based on the timing chart will be described.

FIG. 10 (a) shows the division multiplexed signal light _{P S} when of from ch1 ch4. Wavelength conversion is performed for each channel (for each bit).
FIG. 10 (b) shows an optical pulse generator output light P _P is an optical pulse generated from the optical pulse generator 12. As shown in the figure, the intensity of the optical pulse generator output light P _P is constant.
Figure 10 (c) shows the control light P _C of changing the inclination for each optical pulse with a gradient control unit 14. In the figure, since the magnitude of the inclination of the optical pulse corresponding to ch1 to ch4 is in the order of ch2>ch4>ch3> ch1, the wavelength shift amount of the optical pulse subjected to wavelength conversion increases in this order.

FIG. 10 (d) in the optical coupler 22 shows a combined light P _G in the state where the signal light P _S and a variable delay in the delay circuit 20 delay control light P _D are multiplexed. The signal light P _S which is a timing adjusted as shown in the figures and the control light P _C is input to the wavelength converter 16.

As shown in FIG. 10 (e), in the wavelength conversion unit 16, the optical pulse signal of each channel of the signal light P _S is frequency shifted in accordance with the tilt of the sawtooth pulse of the corresponding control light P _C, the wavelength conversion It is output as device output light P _M. At this time, the slope of the sawtooth pulse of the control light _{P C} is, ch2>ch4>ch3> Since a was the ch1, the wavelength lambda ₁ of each channel after the wavelength _{conversion, λ 2, λ 3, λ} 4 is, lambda ₂ The order is> λ ₄ > λ ₃ > λ ₁ . That is, the wavelength arrangement of the wavelength converter output light P _M becomes positioned as shown in the wavelength arrangement of FIG.

Here, the mutual relationship among the wavelength control signal CS ₂ , the slope of the sawtooth pulse, and the conversion wavelength may be stored in advance in a storage unit (not shown) such as a ROM connected to the wavelength conversion device control unit 18. Good.

By the above described operation, the wavelength converter 10 outputs the time division multiplexed input signal light P _S as a wavelength division multiplexed wavelength converter output light P _M.
According to the wavelength conversion device 10 of the present embodiment, it is possible to convert the wavelength in a gradient controller 14 which is constituted by the optical modulator or the like by varying the intensity of the control light P _C is serrated pulses, high speed It is possible to switch (switch) the wavelength.

  As described above, the wavelength conversion device according to the present embodiment can also generate an optical pulse train having a constant gradient, and the wavelength of the input signal light can be switched by adjusting the intensity thereof. A wavelength converter can be provided.

[Third Embodiment]
FIG. 11 shows a wavelength conversion device 40 according to the present embodiment.
Whereas the wavelength conversion device 10 according to the second embodiment performs wavelength conversion in units of bits, the wavelength conversion device 40 according to the present embodiment is a mode that performs wavelength conversion in units of packets. The configuration is the same as that of the wavelength converter 10 shown in FIG.

  In the wavelength conversion device 40 according to the present embodiment, the wavelength of each input packet is not particularly limited, and can be applied in the same manner regardless of the wavelength combination of each packet. it can. For example, all may be composed of packets having the same wavelength, or may include packets having different wavelengths.

  As shown in FIG. 12, the packet 200 includes a normal header area 204 and a data area 206. The header area 204 includes information necessary for data transmission such as a source address and a destination address, and the data area 206 includes a main body of information to be transmitted. The header area 204 and the data area 206 are collectively referred to as a frame 202. In packet communication, since individual packets are transmitted in bursts, that is, discretely, high-speed responsiveness is also required for wavelength conversion devices that perform wavelength conversion on a packet basis.

The operation of the wavelength conversion device 40 will be described with reference to FIG. In the figure, each packet is shown as four lines in units of 4 bits, and numbers 1 to 4 are assigned in order from the earliest in time. In addition, the guard time provided between the packets is also shown.
Synchronization signal detection section 24 sends the information included in the header area 204, the start position of the packet, reads a type or the like of the packet, the synchronization as the signal S _S to the wavelength converter control unit 18.

Wavelength converter control unit 18 that has received the synchronization signal S _S, based on the synchronous signal S _S, sends the optical pulse generator 12 generates a frequency control signal CS _1, and generates a wavelength control signal CS ₂ gradient sent to the control unit 14 sends the variable delay 20 generates a delay time control signal CS _3, and controls, respectively.

In the wavelength conversion device 40, the control light P _C output from the gradient control unit 14 is generated in packet units, the serrated pulse train of the same strength by the number of bits included in one frame (in FIG. 11 4 bits) and Become. Control light P _C is a delay control light P _D is delayed by the variable delay unit 20, after adjusting the head timing of the corresponding packet signals, are multiplexed by the optical coupler 22, it is guided to the wavelength conversion unit 16. In the wavelength converter 16, the bits contained in the same packet is translated into the same wavelength, the wavelength conversion in units of packets, are output from the output port 146 as the wavelength conversion device output light P _M.

  For subsequent packets, wavelength conversion is performed on a packet-by-packet basis with different conversion wavelengths or with the same conversion wavelength as described above. The wavelength conversion device control unit 18 may perform wavelength allocation (wavelength allocation for each packet) to be converted based on a destination address included in the header area 204.

In Figure 11, the wavelength of the packet 1 to packet 4, in the wavelength conversion device output light P _M, it is converted to the λ4 no .lambda.1. Since the magnitude of the gradient of the delay control light _{P D} has a ch3>ch2>ch1> ch4, wavelength after wavelength conversion, λ3>λ2>λ1> λ4, and the wavelength of the wavelength conversion device output light _{P M} The arrangement is as shown in FIG. Here, the inclination of the delay control light P _D corresponding to the packet 4 is negative, the wavelength λ4 is shifted to the smaller direction to the original wavelength.

  In the present embodiment, since a guard time is provided between packets, for example, when the gradient is controlled by the gradient control unit 14 as shown in FIG. 11 as the wavelength switching time, Even if a state where the light intensity does not reach the control value transiently occurs, there is no problem, and it is sufficient that the light intensity reaches the control value during the guard time.

As described above, the wavelength conversion device according to the present embodiment can also generate an optical pulse train having a constant gradient, and the wavelength of the input signal light can be switched by adjusting the intensity thereof. A wavelength converter can be provided.
Furthermore, the wavelength converter according to the present embodiment is suitable for wavelength conversion of bursty signals such as packet transmission.

[Fourth Embodiment]
In the present embodiment, the wavelength conversion device 10 according to the second embodiment is applied to the time division demultiplexing device 50. The time division demultiplexing device is a device that demultiplexes a single wavelength signal (OTDM signal) that has been time division multiplexed for each channel (Demultiplexing: DEMUX). The time division demultiplexing device 50 adopts a mode in which the wavelength is changed by changing the wavelength for each channel and the spectral element is separated for each channel. The time division demultiplexing device 50 also functions as a path switching device that can arbitrarily change the transmission destination by dynamically switching the conversion wavelength.

The time division demultiplexing device 50 will be described with reference to FIG.
In FIG. 13, the time division demultiplexing device 50 includes a wavelength conversion device 10 according to the second embodiment and a duplexer 502 as a spectroscopic element connected to the output port 146 of the wavelength conversion device 10, an O / E conversion. (Optical / Electrical Converter: optical / electrical converter) 504 and a transmission line 506. OTDM number of multiplexed signal light _{P S} is 4, to no ch1 ch4 are multiplexed. Similar to FIG. 7, OTDM signal light P _S, the wavelength conversion is performed by changing the wavelength in the wavelength conversion device 10 for each bit of each channel, the output port 146 of the wavelength converter 10 as a wavelength converter output light P _M Is output to the duplexer 502.

Duplexer 502, depending on the wavelength of each channel, for separating the wavelength converter output light P _M for each channel. Some of the channels of the separated signal light P _S is input to the O / E converter 504 associated with fractionated demultiplexer 50 when, is converted into an electric signal to generate a received signal. The channel in this case may be called a drop channel. Also, the other channels of the separated signal light P _S, sometimes it is input to the other transmission line 506, it is further transmitted towards the other nodes (relay device). The channel in this case may be called a through channel. In FIG. 13, ch1 and ch4 are drop channels, and ch2 and ch3 are through channels.
Note that the duplexer 502 may be configured using AWG or the like as an example.

  As described above, the time division demultiplexing apparatus 50 according to the present embodiment employs the wavelength conversion apparatus 10 according to the second embodiment, so that time division multiplexed signal light can be collectively separated. ing.

In addition, the time division demultiplexing device 50 can perform high-speed wavelength routing in units of channels by dynamically changing the wavelength of the control light in the control light generation unit 30 in FIG. That is, for example, ch1 that was a drop channel can be changed to a through channel by changing the output terminal of the duplexer 502 by changing the wavelength.
Furthermore, if the wavelength is dynamically changed in units of packets, high-speed wavelength routing in units of packets becomes possible.

  As described above, the wavelength conversion device according to the present embodiment can also generate an optical pulse train having a constant gradient, and the wavelength of the input signal light can be switched by adjusting the intensity thereof. A wavelength converter can be provided.

  In each of the above embodiments, in order to compensate for the loss in each function, an EDFA (Erbium Doped Fiber Amplifier) or SOA (Semiconductor Optical Amplifier) is provided at an appropriate position. An optical amplifier may be provided.

The disclosure of Japanese application 2012-283058 is incorporated herein by reference in its entirety.
All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually described to be incorporated by reference, Incorporated herein by reference.

DESCRIPTION OF SYMBOLS 10 Wavelength converter 12 Optical pulse generator 14 Gradient controller 16 Wavelength converter 18 Wavelength converter controller 20 Variable delay device 22 Optical coupler 24 Synchronization signal detector 30 Control light generator 40 Wavelength converter 50 Time division demultiplexer 64 Optical filter 66 First input port 67 Second input port 68 Output port 70 Pulse laser 72, 72A, 72B Optical pulse shaper 74 Single frequency laser 76 Optical comb generator 78 Signal generator 80 Optical pulse generator 82 2 × 1 optical switch 90 wavelength converter 146 output port 200 packet 202 frame 204 header area 206 data area 502 duplexer 504 O / E converter 506 transmission line 800 wavelength converter 802 highly nonlinear fiber 804 optical filter 810 first Input port 812 Second input port 814 Output port 00 wavelength converter 902 highly nonlinear fiber 910 first input port 912 a second input port 914 the output port 916 circulator 918 SSFBG
P _S signal light _{P C} control light _{P P} optical pulse generator output light _{P D} delay control light _{P G} multiplexed light _{P M} wavelength converter output light

Claims (15)

In the apparatus for converting the wavelength of the signal light pulse train by temporally superposing and inputting the signal light pulse train and the control light pulse train,
An optical pulse generator that generates an optical pulse train that includes an optical pulse having a waveform including a constant or substantially constant gradient portion at least in part, and the waveform of each optical pulse is the same;
A gradient controller for controlling the magnitude of the gradient of each optical pulse of the optical pulse train input from the optical pulse generator to generate a control optical pulse train;
A wavelength for inputting the signal light pulse train and the control light pulse train, shifting the center wavelength of each pulse of the signal light pulse train according to the gradient of the control light pulse train, and changing the wavelength of the signal light pulse train to be output A conversion unit;
Including a wavelength conversion device. The signal light pulse train is an optical signal obtained by time-division multiplexing optical signals of a plurality of channels,
The wavelength to be converted is determined for each channel, and the gradient control apparatus is controlled so that a control optical pulse train having a gradient according to the shift amount of the wavelength and having the number of channels as a cycle is generated. Further comprising a control device;
The wavelength conversion device according to claim 1, wherein the wavelength conversion unit converts the wavelength of the signal light pulse train with a shift amount different for each channel and outputs the converted signal as an output optical signal. A detection device for detecting a leading position of the signal light pulse train;
At least one of the signal light pulse train input from the detection device and the control light pulse train input from the gradient control device is delayed, and a time difference between the head position of the signal light pulse train and the head position of the control light pulse train is determined. A variable delay device for adjusting,
3. The control device adjusts the time difference by controlling the variable delay device such that a temporal overlap between the signal light pulse train and the control light pulse train causes wavelength conversion in the wavelength conversion unit. The wavelength converter described in 1. And a spectral element having an input terminal for inputting the output optical signal output from the wavelength converter, and a plurality of output terminals for separating and outputting the channel included in the output optical signal according to the wavelength. Item 4. The wavelength converter according to Item 2 or Item 3. The plurality of output terminals are connected to different destinations,
The control device controls the gradient control device so that the output end from which the optical signal of the channel is output becomes the output end connected to the changed transmission destination in accordance with the change of the transmission destination of the channel. The wavelength converter according to claim 4, wherein the gradient of each optical pulse of the control optical pulse train corresponding to the channel is changed to a gradient corresponding to the wavelength corresponding to the changed output end. The signal light pulse train is an optical signal composed of a plurality of packets arranged in time series,
A wavelength to be converted is determined for each packet, and a control optical pulse train having a gradient according to the shift amount of the wavelength and having a period of the number of bits included in the packet is generated for each packet. A second control device for controlling the gradient control device,
The wavelength conversion device according to claim 1, wherein the wavelength conversion unit converts the wavelength of the signal light pulse train with a shift amount different for each packet, and outputs the converted signal as an output optical signal. A detection device for detecting the head position of each packet;
At least one of the signal light pulse train input from the detection device and the control light pulse train input from the gradient control device is delayed, and a time difference between the head position of the signal light pulse train and the head position of the control light pulse train is determined. A variable delay device for adjusting,
The second control device adjusts the time difference by controlling the variable delay device such that a time overlap between the signal light pulse train and the control light pulse train causes wavelength conversion in the wavelength converter. The wavelength conversion device according to claim 6. And further comprising: a spectroscopic element having an input terminal for inputting the output optical signal output from the wavelength converter, and a plurality of output terminals for separating and outputting the packet included in the output optical signal according to the wavelength. Item 8. The wavelength converter according to Item 6 or Item 7. The plurality of output terminals are connected to different destinations,
In accordance with the change of the transmission destination of the packet, the second control device is configured so that the output end from which the optical signal of the packet is output becomes the output end connected to the changed transmission destination. The wavelength conversion device according to claim 8, wherein the gradient of each optical pulse of the control optical pulse train corresponding to the packet is changed to a gradient corresponding to the wavelength corresponding to the changed output end. 10. The waveform of each of the control light pulse trains is a waveform having a constant or substantially constant gradient in at least one of a rising portion and a falling portion. 11. Wavelength converter. The waveform of each light pulse of the control light pulse train has a constant or substantially constant gradient at the rising portion and a sawtooth waveform in which the falling portion rapidly falls, or a constant or substantially constant gradient at the falling portion. The wavelength conversion device according to any one of claims 1 to 10, wherein the wavelength conversion device has a sawtooth waveform having a rising portion that rises quickly. The wavelength converter according to any one of claims 1 to 11, wherein the gradient control device controls the magnitude of the gradient by controlling the intensity of each optical pulse included in the input optical pulse train. . The wavelength converter according to any one of claims 1 to 12, wherein the wavelength converter is configured using a nonlinear optical element including a nonlinear fiber or a nonlinear optical crystal. The optical pulse generator divides a part of the output and feeds back and controls the optical spectrum measured through the optical spectrum analyzer and the pulse waveform measured through the optical sampling oscilloscope. The wavelength converter according to any one of claims 1 to 13, wherein the wavelength converter is an optical pulse synthesizer that generates optical pulse trains having the same waveform. The optical pulse generation device generates and outputs a first optical pulse having a waveform including a constant or substantially constant positive gradient portion by controlling the intensity and phase of the optical pulse input from the pulse light source and the pulse light source. A second optical pulse shaper that generates and outputs an optical pulse having a waveform including a constant or substantially constant negative gradient portion by controlling the intensity and phase of the optical pulse input from the pulse light source. And an optical switch that selects one of the output of the first optical pulse shaper and the output of the second optical pulse shaper and outputs the same as an optical pulse train having the same waveform The wavelength converter according to any one of claims 1 to 14.

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