JPH1184439A - Fully optical time-division optical pulse separation circuit and fully optically tdm-wdm conversion circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to collectively output the all channels of a time-division multiplex signal optical pulse train to respective different output ports by modulating light intensity, demultiplexing the control optical pulses of the optical frequencies corresponding to respective lower order group signal channels and outputting these pulses to the respective ports corresponding to the respective optical frequencies. SOLUTION: The lower order group signal channels #1 to #N of a time-division multiplex signal optical pulse train and the parts having optical frequencies ν1 to νN of a control optical pulse are so synthesized as to overlap on the time base in an optical synthesizer 12 and are introduced to an optical Kerr medium 14. The control pulses are subjected to an optical frequency shift by the mutual phase modulation of the time-division multiplex signal optical pulse train. The optical spectral components centering at the optical frequencies ν1 to νN of the control optical pulses are respectively subjected to intensity modulation by the lower order group signal channels #1 to #N. The control optical pulses past the optical Kerr medium 14 are inputted to an optical demultiplexer 15 and are demultiplexed near the optical frequencies ν1 to νN. The demultiplexed pulses are separated and outputted to respective corresponding output ports.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-channel output type all-optical type in which a time-division multiplexed signal optical pulse train is separated on a time axis and each low-order group signal channel is collectively output to a different output port. The present invention relates to a time division optical pulse separation circuit.

Further, according to the present invention, a different wavelength is assigned to each lower-order group signal channel of a time-division multiplexed signal optical pulse train inputted from a transmission line, and the wavelength is converted into a wavelength-division multiplexed signal optical pulse train and transmitted to the transmission line. The present invention relates to an optical TDM-WDM conversion circuit.

[0003]

2. Description of the Related Art FIG. 18 shows a first configuration example of a conventional all-optical time-division optical pulse separation circuit (Japanese Patent Laid-Open No. 4-19718).
5 and 6 of Japanese Patent Application Laid-open No. Hei 2-125176.
Figure). This configuration inputs a signal light pulse and a control light pulse that are time-division multiplexed into an optical Kerr medium, and utilizes the fact that the signal light pulse undergoes mutual phase modulation from the control light pulse to change its center frequency. The signal is demultiplexed corresponding to the low-order group signal channel.

In FIG. 1, a time-division multiplexed optical frequency ν
The signal light pulses P ₁ , P ₂ , P ₃ , and P _{4 of s} are input to the optical multiplexer 1 and multiplexed with the control light pulse Pc of the optical frequency νc to form an optical Kerr medium 3 having a positive nonlinear refractive index. Be guided. In the optical Kerr medium 3, the center frequency of the signal light pulse changes due to the mutual phase modulation received from the control light pulse. This is shown in FIG.

[0005] In the optical Kerr medium 3 having a positive nonlinear refractive index, a phase change 4 is induced in the signal light pulse by the cross-phase modulation of the control light pulse. This phase change 4 is proportional to the intensity waveform of the control light pulse, and an optical frequency shift 5 given by its time derivative is applied to the signal light pulse.
Here, when a so-called up-chirp region where the optical frequency increases almost linearly with time (the central portion of the control light waveform, a region shaded in FIG. 19) is used, the signal light pulses P ₁ , P The optical frequencies of ₂ , P ₃ and P ₄ are converted from νs into ν ₁ , ν ₂ , ν ₃ and ν ₄ which are different from each other.

The signal light pulses P ₁ , P ₂ , P ₃ , and P ₄ whose optical frequencies have been changed in this manner can be separated by the optical demultiplexer 2 for each optical frequency. That is, an all-optical time-division optical pulse separation circuit that separates the time-division multiplexed signal light into low-order group signal channels and outputs the signals to different output ports collectively is configured.

FIG. 20 shows a second configuration example of a conventional all-optical time-division optical pulse separation circuit (FIGS. 1 and 3 of Japanese Patent Application Laid-Open No. Hei 9-15661 (Japanese Patent Application No. Hei 7-160678)). In this configuration, a time-division multiplexed signal light pulse and a control light pulse having chirping are input to a nonlinear loop mirror (Sagnac interferometer) using an optical Kerr medium, and cross phase modulation is performed from the signal light pulse in the optical Kerr medium. The control light pulse output after being subjected to the phase shift is demultiplexed corresponding to each low-order group signal channel.

In the figure, an input port 6A of an optical coupler 6
Is connected to a control light source 7, the output ports 6C and 6D are coupled in a loop via the optical multiplexer 1 and the optical Kerr medium 3, and the input port 6B is connected to the optical demultiplexer 2.

The time-division multiplexed signal light pulses P ₁ , P ₂ , P ₃ ,..., P _N of the optical frequency νs are input to the optical multiplexer 1 via the optical amplifier 8. Control light source 7 has a chirping optical frequency varies in time substantially linear, and the signal light pulse _{P 1, P 2, P 3} , ..., a control pulse Pc having a time width containing P _N Occur. The control light pulse Pc is input to the input port 6A of the optical coupler 6, is divided into two, and propagates from the output ports 6C and 6D in the loop as clockwise and counterclockwise components in both directions. On the other hand, the signal light pulse input into the loop from the optical multiplexer 1 propagates clockwise. At this time, in the optical Kerr medium 3, the phase of the clockwise control light pulse that propagates overlapping with the signal light pulse changes due to the cross-phase modulation of the signal light pulse. Therefore, when the clockwise and counterclockwise control light pulses are multiplexed again by the optical coupler 6, the control light pulse overlapping with the signal light pulse has a relative phase difference of π and is output from the input port 6B. You.

Thus, the signal light pulses P ₁ , P ₂ , P
_3, ..., the control light pulse corresponding to _{P N Pc 1, Pc 2,} Pc 3,
.., Pc _N are switched. These control light pulses Pc ₁ , P
_{c 2, Pc 3, ...,} Pc N is ₁ optical frequency ν, ν _2, ν _3,
, Ν _N , and can be separated by the optical demultiplexer 2 for each optical frequency. That is, an all-optical time-division optical pulse separation circuit that separates the time-division multiplexed signal light into low-order group signal channels and outputs the signals to different output ports collectively is configured.

FIG. 21 shows a third configuration example of a conventional all-optical time-division optical pulse separation circuit (Japanese Patent Laid-Open No. Hei 8-110534).
6 and 7 of Japanese Patent Application Laid-Open No. 7-208258, priority number: Japanese Patent Application No. 6-191645. This configuration inputs a signal light pulse time-division multiplexed to a nonlinear optical medium and a control light pulse having chirping, and demultiplexes an optical pulse corresponding to each lower-order group signal channel generated by four-wave mixing. is there.

In the figure, the time-division multiplexed optical frequency ν
The s signal light pulses P ₁ , P ₂ , P ₃ ,..., _PN are input to the optical multiplexer 1. The control light source 7 has chirping in which the optical frequency changes almost monotonically with time, and the signal light pulse P
_{1, P 2, P 3,} ..., generates a control pulse Pc having a time width containing P _N. The signal light pulses P ₁ , P ₂ , P ₃ ,..., P _N
And the control light pulse Pc are multiplexed by the optical multiplexer 1 and guided to the nonlinear optical medium 9.

The signal light pulses P ₁ , P ₂ , P ₃ , at the optical frequency ν _s
..., the optical frequency component of the control light pulse Pc synchronized with _PN is ν
₁ , ν ₂ , ν ₃ ,..., Ν _N. At this time, in the nonlinear optical medium 9, the signal light pulse of each channel induces a four-wave mixing effect with the control light pulse of a different optical frequency, and the converted light pulse F of the optical frequency ν _Fi (= 2ν _s −ν _i ). _i , or a converted optical pulse Fi 'of an optical frequency ν _Fi ′ (= 2ν _i −ν _s ) is generated (i = 1, 2, 3,..., N).

Thus, the signal light pulses P ₁ , P ₂ , P
_3, ..., converted light pulse corresponding to _{P N F 1, F 2,} F 3, ..., F N
Alternatively, F ₁ ′, F ₂ ′, F ₃ ′,..., F _N ′ are generated, and can be separated by the optical demultiplexer 2 for each optical frequency. That is, the time-division multiplexed signal light is separated into low-order group signal channels,
In addition, an all-optical time-division optical pulse separation circuit that collectively outputs to different output ports is configured.

The first and third structural examples of the conventional all-optical time-division optical pulse separation circuit described above are disclosed in Japanese Patent Application Laid-Open No. 8-307391 (Japanese Patent Application No. 7-12963).
3) also shows a conventional example (FIG. 6) and a configuration of the invention (FIGS. 1 and 2).

[0016]

In the first configuration example (FIGS. 18 and 19) of the conventional all-optical time-division optical pulse separation circuit,
Since only the central portion of the control light pulse, that is, the time region where the optical frequency of the signal light pulse increases almost monotonically with time, can be used, the signal light pulse time-division multiplexed cannot be separated beyond the time region. Further, in order to obtain a large optical frequency shift using a control light pulse having a large pulse width, a very large control light power of several W to several tens of W is required (Electron. Lett., Vol. 28, pp.
1070-1071, 1992). Further, the separated optical pulse is obtained by shifting the optical frequency of the signal optical pulse, and the signal optical pulse of the original optical frequency is not output.

In the second example of the conventional all-optical time-division optical pulse separation circuit (FIG. 20), it is necessary to configure a non-linear loop mirror (Sagnac interferometer). It is more complex than other conventional configurations that pass the Kerr medium in one direction.

In the third configuration example (FIG. 21) of the conventional all-optical time-division optical pulse separation circuit, four-wave mixing light generated from a signal light pulse and a control light pulse is used as output light. There is a problem that the insertion loss increases with the wavelength conversion loss caused by the mixed light generation efficiency. Further, since the band of the four-wave mixing light is greatly shifted from the band of the signal light pulse and the band of the control light pulse, there is a problem that a wide optical bandwidth is required for the time division light pulse separation operation.

According to the present invention, all the channels of a time-division multiplexed signal light pulse train are output to different output ports collectively, with a simple structure, with a smaller control light power, and without increasing the optical bandwidth. It is an object of the present invention to provide an all-optical time-division optical pulse separation circuit and an all-optical TDM-WDM conversion circuit for converting a time-division multiplexed signal optical pulse train into a wavelength-division multiplexed signal optical pulse train.

[0020]

An all-optical time-division optical pulse separation circuit according to the present invention is a time-division optical signal vs. time-division multiplexing of N (N is an integer of 2 or more) low-order group signal channels. A multi-signal optical pulse train and a low-order group signal channel of the time-division multiplex signal optical pulse train, having chirping that changes monotonically with time at an optical frequency different from the optical frequency vs, and N low-order groups A control light pulse having a time width including the signal channel and having the same repetition as the low-order group signal channel is multiplexed and input to the optical Kerr medium.

In the optical Kerr medium, the control light pulse is locally cross-phase-modulated on the time axis in accordance with the presence or absence of the signal light pulse of each low-order group signal channel of the time-division multiplexed signal light pulse train, and the control light pulse By inducing an optical frequency shift that compensates for the chirping of the control optical pulse in the optical frequency axis direction, the optical frequencies ν ₁ and ν of the control optical pulse corresponding to each low-order group signal channel
₂ ,…, modulates the light intensity of the ν _N component. This light intensity is modulated, and the optical frequencies ν ₁ and ν corresponding to each low-order group signal channel
₂ ,..., Ν _N are demultiplexed and output to ports corresponding to each optical frequency.

Here, the time-division multiplexed signal light pulse train input to the optical Kerr medium is amplified in the optical Kerr medium so as to have a light intensity sufficient to give cross-phase modulation to the control light pulse. Item 2). In the optical Kerr medium, cross-phase modulation is applied to the control light pulse depending on the presence or absence of the signal light pulse, and a frequency shift that compensates the chirping of the control light pulse in the optical frequency axis direction is induced, so that the light intensity of the control light pulse is increased. The principle of modulation will be described below. In addition,
In the following description, it is assumed that the optical Kerr medium has a positive nonlinear refractive index.

As shown in FIG. 2, it is assumed that the signal light pulse has a Gaussian time intensity waveform and the control light pulse has a rectangular time intensity waveform. Further, it is assumed that the control light pulse has a down chirp (ν _L > ν _T ) in which the optical frequency monotonously decreases from the leading end (ν _L ) to the trailing end (ν _T ) of the pulse. The optical frequency of the control light pulse at time t ₀ at which the signal light pulse has a peak is ν ₀ .

At this time, the control light pulse undergoes an optical frequency shift as shown in FIG. 3 (b) due to the cross-phase modulation by the signal light pulse shown in FIG. 3 (a). That is, in the central part of the signal light pulse (the area shaded in FIG. 3B), the control light pulse undergoes an optical frequency change (up chirp) in which the optical frequency increases almost linearly with time.
Thus, the down chirp of the control light pulse is
Is compensated in the optical frequency axis direction by the up-chirp received from the optical signal pulse, resulting in a center and an optical frequency [nu ₀ around the optical frequency components overlap in time of the signal light pulse is converted into [nu _0, [nu ₀ spectral intensity in the vicinity Increase. This situation is shown in FIGS. 4 (c) and 4 (d).

FIGS. 4A and 4B show a time-resolved spectral spectrum and a light spectrum intensity distribution of a control light pulse which is not subjected to an optical frequency shift by a signal light pulse. FIG.
(c) and (d) show the time-resolved spectral spectrum and the optical spectrum intensity distribution of the control light pulse that has been subjected to the optical frequency shift by the signal light pulse.

As shown in FIGS. 4B and 4D, the intensity of the optical frequency ν ₀ component of the control light pulse becomes P ₁ or P ₀ depending on the presence or absence of the signal light pulse. Therefore, by demultiplexing the control light pulse by an optical bandpass filter that transmits near the optical frequency ν _0, it is possible to obtain an optical pulse whose light intensity is modulated by the presence or absence of the signal light pulse.

FIG. 5 shows a time-division multiplexed signal light pulse train “11101” in which signal light pulses of five channels are time-division multiplexed.
And a time intensity waveform of the corresponding control light pulse. Here, the control light pulse has 1/5 repetition of the time-division multiplexed signal light. Each channel #
1 the optical frequency of the control pulse signal light pulse # 5 at time t ₁ ~t ₅ showing the peaks and ν ₁ ~ν _5.

At this time, as shown in FIGS. 6A and 6B, the spectral intensity of the control light pulse is modulated in accordance with the modulation pattern "11101" of the time-division multiplexed signal light pulse train. Thus, each low-order group signal channels of the channel # 1 to # 5, by demultiplexing by the optical band-pass filter transmitting light frequency ν ₁ ~ν ₅ near each can be removed separately.

In the above description, the optical Kerr medium has a positive nonlinear refractive index, and the control light pulse has a down chirp in which the optical frequency monotonously decreases from the leading end to the trailing end of the pulse ( Claim 3). On the other hand, when the optical Kerr medium has a negative nonlinear refractive index, a control light pulse having an up chirp in which the optical frequency monotonically increases from the leading end to the trailing end of the pulse may be used. ).
Further, when the optical Kerr medium has birefringence, the optical Kerr medium includes a polarization dispersion compensating means for compensating the polarization dispersion between the two orthogonal main axes, and the control light includes two orthogonal main axes of the optical Kerr medium. The polarization components in the directions have polarizations having the same intensity (claim 5).

Further, this polarization dispersion compensating means can be formed by cascading two optical Kerr media having the same length of birefringence so that their main axes are orthogonal to each other. As an example, FIG. 24 shows a case where the birefringent medium 60 and the birefringent medium 61 are connected. Further, a λ / 2 plate can be interposed between the cascade connections (claim 13). As an example, FIG. 25 shows a case where a λ / 2 plate is interposed between a birefringent medium 60 and a birefringent medium 61.

Alternatively, a Faraday rotator can be interposed between the cascade connections. As an example of this, FIG. 26 shows a case where a 90-degree Faraday rotator is interposed between the birefringent medium 60 and the birefringent medium 61. As a result, light propagating along the fast axis and the slow axis of the birefringent medium 60 propagates along the slow axis and the fast axis of the birefringent medium 61, respectively. The propagation delay difference between the main axes, that is, the polarization dispersion, becomes zero.

In the all-optical time-division optical pulse separation circuit of the present invention, the optical pulses of optical frequencies ν _{1 to} ν ₅ are demultiplexed and output to each port, but the all-optical TDM-WDM of the present invention is used. The conversion circuit combines the optical pulses of each optical frequency again, and outputs the resultant signal to one port as a wavelength division multiplexed signal optical pulse train (claims 6 to 9). This all-optical TDM-WDM
Similarly, in the case where the optical Kerr medium has birefringence in the conversion circuit, the optical Kerr medium includes a polarization dispersion compensating means for compensating the polarization dispersion between two orthogonal main axes. The polarization components in two orthogonal main axis directions have the same intensity (claim 10).

Further, the polarization dispersion compensating means can cascade two optical Kerr media having the same length of birefringence so that their main axes are orthogonal to each other. As an example, FIG. 24 shows a case where the birefringent medium 60 and the birefringent medium 61 are connected. A λ / 2 plate can be interposed between the cascade connections (claim 14). As an example, FIG. 25 shows a case where a λ / 2 plate is interposed between a birefringent medium 60 and a birefringent medium 61. Alternatively, a Faraday rotator can be interposed between the cascade connections (claim 16). As an example of this, FIG. 26 shows a case where a 90-degree Faraday rotator is interposed between the birefringent medium 60 and the birefringent medium 61. As a result, light propagating along the fast axis and the slow axis of the birefringent medium 60 propagates along the slow axis and the fast axis of the birefringent medium 61, respectively. The propagation delay difference between the main axes, that is, the polarization dispersion, becomes zero.

As shown in FIG. 4D, the optical frequency ν
_Since the optical frequency components around ₀ are converted into ν ₀ , the optical frequency components (ν ₀ ± δ) around ν ₀ are also relatively intensity-modulated. That is, when there is a signal light pulse, the optical frequency component near ν ₀ increases, while the optical frequency component near (ν ₀ ± δ) decreases. Therefore, by demultiplexing the intensity modulation component with an optical bandpass filter that transmits near the optical frequency (ν ₀ + δ) or (ν ₀ −δ), the input time-division multiplexed signal optical pulse train is logically inverted. The output optical pulse train can be output. In particular, when the repetition of the signal light pulse train and the control light pulse are equal,
It can be operated as an all-optical logic inversion circuit.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment of All-Optical Time-Division Optical Pulse Separation Circuit) FIG. 1 shows the configuration of a first embodiment of an all-optical time-division optical pulse separation circuit of the present invention.

In the figure, channel # 1 to channel #
Optical frequency vs obtained by time-division multiplexing of N low-order group signal channels
Is input to the optical multiplexer 12 via the optical amplifier 11. The control light source 13 has a repetition equal to that of the low-order group signal channel of the time-division multiplexed signal light pulse train, and a down chirp (ν ₁ > ν ₂ >) in which the optical frequency monotonously decreases from the leading end to the trailing end of the pulse. > Ν _N ) is generated and input to the optical multiplexer 12.

In the optical multiplexer 12, each low-order group signal channel # 1, # 2, # 3,.
And N, the optical frequency [nu ₁ of the control _{pulse, ν 2, ν 3, ...} , ν N
Are guided so as to overlap with each other on the time axis and lead to the optical Kerr medium 14. The optical Kerr medium 14 has a positive nonlinear refractive index, and as described above, the control light pulse undergoes an optical frequency shift due to the cross-phase modulation of the time-division multiplexed signal light pulse train. Then, the optical frequency ν ₁ of the control light pulse,
ν _2, ν _3, ..., the light spectral component centered at [nu _N is,
The intensity is modulated by the low-order group signal channels # 1, # 2, # 3,..., #N, respectively.

The control light pulse that has passed through the optical Kerr medium 14 is input to the optical demultiplexer 15 and has optical frequencies ν ₁ , ν ₂ , ν ₃ ,
..., near [nu _N is demultiplexed and outputted is separated into the corresponding output port. At the same time, a time-division multiplexed signal light pulse train having the optical frequency vs may be output.

FIG. 7 shows the positional relationship on the time axis between the time-division multiplexed signal light pulse train and the control light pulse in the all-optical time-division light pulse separation circuit of the present invention. Here, the time-division multiplexed signal light pulse train (optical frequency vs) is “011... 1”,
It is assumed that "110 ... 1" and "101 ... 1". Channel # 1
The low-order group signal channel of (optical frequency ν ₁ ) is “011 ...”
, And similarly in the following.

FIG. 8 shows a configuration example of the optical demultiplexer 15 having 1 input and N outputs. optical demultiplexer shown in (a), the optical divider 21 to N branching input light, ₁ is the transmitted light frequency [nu, [nu _2, ..., the optical bandpass filter 22-1 to 22-N of the [nu _N Be composed.

The optical demultiplexer shown in FIG.
3. The optical demultiplexer shown in (c) is composed of an arrayed waveguide diffraction grating 24. The arrayed waveguide diffraction grating 24 includes an input waveguide 25, a slab waveguide 26, and an arrayed waveguide (the waveguides in contact with each other have an optical path length difference of ΔL).
27, a slab waveguide 28, and an output waveguide array 29. From the input waveguide 25 to the slab waveguide 26
The light distributed to the array waveguide 27 via the optical waveguide has a different phase state after passing through the array waveguide 27 due to a difference in optical frequency, and a convergence position in the slab waveguide 28 differs according to the optical frequency. Therefore, light of different optical frequencies is extracted from each waveguide of the output waveguide array 29 and functions as an optical demultiplexer.

FIG. 9 shows a first configuration example of the control light source 13 for generating a control light pulse train having linear chirping. The control light source includes an optical fiber 31 for white pulse generation,
It is configured by connecting a chirp adjusting unit 32 and a wavelength variable bandpass optical filter 33. When a short light pulse (light frequency ν ₀ ) is incident on the white pulse generating optical fiber 31, a wide band white pulse (center light frequency ν ₀ ) is generated. For example, a short optical pulse having a peak power of 2 to 3 W for a few picoseconds and an optical fiber 3 for generating a white pulse having a length of 1 km are used.
When it is incident on 1, a white pulse having a spectrum width of about 200 nm or more is generated.

The wavelength tunable bandpass optical filter 33 has a rectangular spectrum transmission function. When the white pulse input through the chirp adjusting means 32 is split, a control optical pulse train having a wide time width and linear chirping is obtained. Is output. Further, by changing the center transmission wavelength in the white pulse wavelength range, a control light pulse train having linear chirping at an arbitrary optical frequency can be generated. The chirp adjusting means 32 adjusts the absolute value and sign of chirping according to the dispersion characteristics. For example, when a 1.3 μm zero-dispersion fiber is used as the chirp adjusting means 32, 1.
Since the anomalous dispersion value is almost constant in the 55 μm band, a control light pulse having linear down-chirping can be obtained.

FIG. 10 shows a second configuration example of the control light source 13 for generating a control light pulse train having linear chirping. This control light source uses a normal dispersion optical fiber 34 having normal dispersion. When a short light pulse (optical frequency ν ₀ ) is incident on the normal dispersion optical fiber 34, a control light pulse having a wide time width and linear up-chirping is generated due to the combined effect of the self-phase modulation effect and the dispersion. To obtain a control light pulse with linear down-chirping,
As in the case of the first configuration example, a 1.3 μm zero-dispersion fiber may be used as an example of the chirp adjusting unit 32.

FIG. 22 shows an example of the configuration of the third control light source. In this example, a Fabry-Perot resonator type active mode-locked semiconductor laser 50 in which an electro-absorption (EA) modulator is monolithically integrated is used as the control light, and a chirp adjusting means 32 is connected to this. The above-mentioned laser 50 has a wide spectrum width of about 10 nm in general, and can be used as a control light source in the present invention by adjusting the chirp by the chirp adjusting means 32. By using a semiconductor laser as the control light source as in the present configuration example in FIG. 22, the effect that the control light source can be made compact can be obtained. In order to obtain a control light pulse having linear down-chirping, a 1.3 μm zero-dispersion fiber may be used as an example of the chirp adjusting means 32 as in the first and second configuration examples.

FIG. 23 shows another example of the configuration of the chirp adjusting means 32. In this configuration example, an optical circulator 53 and a chirped fiber grating 52 are used. A fiber grating is a device that periodically changes the refractive index of the core of an optical fiber by using the phenomenon that the refractive index increases when a quartz optical fiber doped with GeO ₂ is irradiated with ultraviolet light (light-induced refractive index change). The optical device selectively reflects light having a Bragg wavelength that is a wavelength corresponding to the period.

Furthermore, chirped fiber grading is one in which the grading cycle is gradually changed in the longitudinal direction of the fiber, and the reflection position depends on the wavelength.
That is, it acts as a dispersion material. In FIG.
The control light is input from the port 54 of the optical circulator, output from the port 55, and then input to the chirped fiber grating 52. The control light is chirped and output from the chirped fiber grating due to the wavelength dependence of the reflection position of the chirped fiber grating 52, input again from the port 55 of the optical circulator 53, and output from the port 56.

The optical Kerr medium 14 having a positive nonlinear refractive index
For example, a silica-based optical fiber, a chalcogenide glass mainly containing a chalcogen element such as As or S, a semiconductor laser amplifier, or the like may be used. As the optical Kerr medium 14 having a negative nonlinear refractive index, a π-conjugated organic material, II
Group IV and II-VI compound semiconductors may be used.

When an optical fiber is used, the group velocity dispersion of the optical fiber causes a group delay difference called a walk-off between a signal light pulse and a control light pulse having different wavelengths, which causes crosstalk between channels. Becomes In order to avoid this, in the wavelength band near the zero dispersion wavelength where the group delay characteristic can be approximated by a quadratic curve, the center wavelengths of the signal light pulse and the control light pulse are symmetrical with respect to the zero dispersion wavelength of the optical fiber. And the walk-off amount is desirably set to zero.

FIG. 11 shows a simulation result by numerical calculation of the all-optical time-division optical pulse separation circuit of the present invention. Zero dispersion wavelength 1547nm, length 1km as optical Kerr medium
Is assumed. The center wavelengths of the signal light pulse and the control light pulse were set to 1555 nm and 1539 nm, respectively, so as to be symmetrical with respect to the zero dispersion wavelength. The signal light pulse was a Gaussian pulse having a pulse width of 4 ps and a peak power of 200 mW, and the control light pulse was a down-chirp Gaussian light pulse having a pulse width of 50 ps and a spectral half width of 12 nm.

FIG. 11A shows the time waveforms of the signal light pulse and the control light pulse when the time-division multiplexed signal light pulse train has the pattern "11111". FIG. 11B shows the spectral intensity of the control light pulse after the propagation of the optical Kerr medium. Five peaks are seen corresponding to the signal light pattern. The arrows shown in (a) and (b) are the spectral components of the signal light pulse and the corresponding control light pulse modulated by the signal light pulse.

FIG. 11C shows the time waveforms of the signal light pulse and the control light pulse when the time-division multiplexed signal light pulse train has the pattern "11101". FIG. 11D shows the spectral intensity of the control light pulse after the propagation of the optical Kerr medium. Four peaks are seen corresponding to the signal light pattern. The arrows shown in (c) and (d) are the spectral components of the signal light pulse and the corresponding control light pulse modulated by the signal light pulse.

FIG. 12 shows a time-resolved spectral spectrum of a control light pulse after propagation of the optical Kerr medium in a time-division multiplexed signal light pulse pattern “11101” using a contour graph based on spectrum intensity. In the figure,
The time and the optical frequency indicated by the dotted arrows correspond to the time and the optical frequency of the arrows illustrated in FIGS. 11C and 11D, respectively. As described above, it can be seen that the spectral components of the control light pulse overlapping on the time axis are subjected to intensity modulation depending on the presence or absence of the signal light pulse.

(Second Embodiment of All-Optical Time-Division Optical Pulse Separation Circuit) The amount of frequency shift due to cross-phase modulation, which is a nonlinear optical effect used in the present invention, is the relative polarization of signal light and control light. Depends on the state. Therefore, the operation of the present invention for amplifying the frequency component of the control light pulse overlapping on the time axis with the signal light pulse using the cross-phase modulation of the linearly chirped control light pulse depends on the polarization state of the input signal light. .

In general, the polarization state of signal light propagating through an optical fiber transmission line changes randomly. Therefore,
In the second embodiment, a polarization-independent configuration example in which the operation is not affected by a random change in the polarization state of the signal light will be described. FIG. 27 shows the configuration. put it here,
The same components as those in FIG. 1 will not be described again. In the present embodiment, the output of the optical multiplexer 12 has a polarization dispersion compensator 18 disposed between two birefringent optical Kerr media 19.

In this embodiment, an input signal light having an arbitrary polarization state is incident on the birefringent optical Kerr medium 19, separated into two linearly polarized lights having orthogonal principal axis directions, and the polarization state thereof is changed. While maintaining the birefringent optical Kerr medium 1
Propagating through 9. Here, the power distribution ratio of the input signal light to both principal axis components depends on the state of polarization when the light enters the birefringent optical Kerr medium 19. On the other hand, the control light is incident on the optical Kerr medium such that the power distribution ratio to the two principal axis components is 1: 1. This is realized by, for example, changing the state of polarization of the control light incident on the birefringent optical Kerr medium 19 into a linear polarization having a 45-degree inclination with respect to the direction of one main axis of the birefringent optical Kerr medium 19. it can.

When propagating through the birefringent optical Kerr medium 19,
As described above, the control light is independently subjected to chirp compensation by the cross-phase modulation from the signal light on both principal axes, and the power of the corresponding control light spectral component is increased. At this time, the power increase rate of the spectrum component due to the chirp compensation is proportional to the power of the signal light. Therefore, the birefringent optical Kerr medium 1
The power increase rate of the spectral component due to chirp compensation with respect to the sum of the two control light powers emitted from both principal axes 9 does not depend on the power distribution ratio of the signal light to both principal axes. That is, it does not depend on the polarization state when the input signal light enters the birefringent optical Kerr medium.

In the optical Kerr medium, the polarization dispersion compensating means 18 for interchanging the fast axis and the slow axis is inserted at the intermediate point, so that the optical path lengths on the two axes are equal, and the time of the two polarization components is equal. Off-axis deviations are compensated. Examples of the polarization dispersion compensating means 18 are shown in FIGS. Therefore, this configuration can realize an operation independent of the polarization of the input signal light without sacrificing the operation band.

The polarization state when the control light is incident on the birefringent optical Kerr medium 19 may be circularly polarized light or
The elliptical polarization may be such that the major axis or the minor axis has an inclination of 45 degrees with respect to one principal axis of the birefringent optical Kerr medium 19. When the propagation loss and the nonlinear refractive index are different between the two principal axes in the birefringent optical Kerr medium 19, the power distribution ratio of the control light to the two principal axes of the birefringent optical Kerr medium 19 is adjusted. Polarization-independent operation becomes possible.

Further, the polarization dispersion compensating means 18
When the polarization states of the two birefringent optical Kerr media 19 are different for some reason, such as variations in various conditions at the time of manufacture, the two are not necessarily the same length, and are not necessarily equal in length so that the polarization dispersion is compensated as a whole. You can adjust the length. Further, as long as the polarization dispersion can be compensated as a whole, there is no particular limitation on the number of birefringent optical Kerr media 19 having different lengths and the number of polarization dispersion compensating means. However,
The configuration of the present embodiment is desirable from the viewpoints of insertion loss, simplicity of the configuration, and the like.

A configuration example based on another viewpoint for avoiding the input polarization dependence of the signal light will be described below. That is, the optical Kerr medium is not a medium having birefringence as described above,
An isotropic optical Kerr medium is used. Therefore, the polarization dispersion compensator 18 is unnecessary. The efficiency of the cross phase modulation used in the present invention depends on the polarization state of the signal light and the control light as described above. When both are linearly polarized and their directions are orthogonal to each other, the worst case is 3 minutes. It becomes 1. That is, it does not become 0 (zero). Therefore, by performing the worst value design that allows some sensitivity deterioration, the light receiving sensitivity of the separated signal light can be made independent of the polarization state of the input signal light.

(Third Embodiment of All-Optical Time-Division Optical Pulse Separation Circuit) The all-optical time-division optical pulse separation circuit of the present invention comprises:
As shown in FIG. 4 or FIG. 6, since the optical frequency shift of the control light pulse by the cross-phase modulation of the signal light pulse is used, the ON / OFF extinction ratio of the intensity modulation is about several dB. Generally, the on / off extinction ratio of the Mach-Zehnder interferometer type optical external modulator using the electro-optic effect of LiNbO ₃ is 25.
Since it is on the order of dB, in the case of the present invention, the discrimination margin or phase margin when discriminating the separated signal light pulse is reduced. Therefore, in the second embodiment, an example in which the ON / OFF extinction ratio of the signal light pulse separated for each channel is improved will be described.

FIG. 13 shows the configuration of a third embodiment of the all-optical time division optical pulse separation circuit of the present invention. The feature of this embodiment is that, in the configuration of the first embodiment shown in FIG. 1, each output port of the optical demultiplexer 15 has an on / off extinction ratio improving means (SA) 16 using a saturable absorber or the like. To connect. Examples of the saturable absorber include a nonlinear loop mirror, a semiconductor material having a bulk or multiple quantum well structure such as GaAs, a nonlinear etalon in which an optical glass containing semiconductor fine particles such as CdS _x Se _1-x is sandwiched between partially transparent mirrors, Further, an optical bistable device, a bistable semiconductor laser, a nonlinear directional coupler, or the like using the Stark effect of excitons in a multiple quantum well can be used.

(Fourth Embodiment of All-Optical Time-Division Optical Pulse Separation Circuit) The optical time-division separation circuit of the present invention converts a TDM signal to a W signal.
When converting to a DM signal, chirp compensation of control light is used. In the converted WDM signal, the ON level has increased power due to the amplification gain due to chirp compensation, but the OFF level has less nonlinear interaction than the signal light, so that chirp compensation does not occur and the original level of the control light does not occur. It has become. Accordingly, the time division demultiplexed signal light obtained by demultiplexing the WDM signal light has a disadvantage that the ON-OFF ratio is small.

However, in the power spectrum of the time-division separated signal subjected to optical-electric conversion shown in FIG.
Most of the energy of the component is concentrated in the emission line spectrum having the repetition frequency of the time division separated signal. This is illustrated in FIG. 28, where the frequency f0 is the repetition frequency. Therefore, by inserting a low-pass filter or a band rejection filter that suppresses this frequency component, the ON-OF of the time-division separated signal in the electrical domain can be obtained.
The F ratio can be improved.

(First Embodiment of All-Optical TDM-WDM Converter) FIG. 14 shows the configuration of the first embodiment of the all-optical TDM-WDM converter of the present invention.

The feature of this embodiment is that, in the configuration of the first embodiment of the all-optical time-division optical pulse separation circuit shown in FIG. 1, the optical frequencies ν ₁ and ν are obtained from the control light pulse passing through the optical Kerr medium 14. ₂ , ν ₃ ,..., Ν _N are demultiplexed, and instead of the optical demultiplexer 15 that separates and outputs the output light to each output port, the demultiplexed control optical pulse is multiplexed to one output port and output. In this configuration, the optical demultiplexer 17 is used. The control optical pulse output from the optical demultiplexer 17 is such that each lower-order group signal channel of the time-division multiplexed signal optical pulse train of the optical frequency νs has the optical frequency ν ₁ ,
It is output as a wavelength division multiplexed signal light pulse train replaced by ν ₂ , ν ₃ , ..., ν _N.

FIG. 15 shows a first configuration example of the optical demultiplexer 17. The optical demultiplexer shown in (a) includes an optical splitter 21 for splitting input light into _N , and optical bandpass filters 22-1 to 22-N having transmitted light frequencies of ν ₁ , ν ₂ ,. , An optical coupler 41 for multiplexing the output light of each optical bandpass filter.

The optical demultiplexer shown in (b) has a configuration in which two arrayed waveguide diffraction gratings 24 shown in FIG. 8 (c) are connected in cascade. That is, the control light pulse having the optical frequencies ν ₁ , ν ₂ ,..., Ν _N is demultiplexed by the arrayed waveguide diffraction grating 24-1.
Further, they are multiplexed by the arrayed waveguide diffraction grating 24-2 and output from one output port.

FIG. 16 shows an all-optical TDM-WDM of the present invention.
5 shows a positional relationship on a time axis between a time-division multiplexed signal light pulse train and a control light pulse in a conversion circuit. Here, the time-division multiplexed signal optical pulse train (optical frequency ν _s ) is “011.
1 "," 110 ... 1 "," 101 ... 1 to. O'clock each low-order group signal channel division multiplexed optical signal pulse train ", respectively optical frequency [nu _1, [nu _2, ..., is converted into [nu _N, wavelength It is output as a division multiplexed signal light pulse train.

(Second Embodiment of All-Optical TDM-WDM Converter) FIG. 29 shows an all-optical TDM-WD converter according to the present invention.
7 shows a configuration of a second embodiment of the M conversion circuit. The feature of this embodiment is that, in the configuration of the second embodiment of the all-optical time-division demultiplexing circuit shown in FIG. 29, the optical frequencies ν ₁ , ν ₂ , ν ₃ ,…,
demultiplexes the neighborhood [nu _s, control light instead of the optical demultiplexer 15 in Figure 1 of a second embodiment of the all-optical TDM-WDM conversion circuit for outputting the separated to each output port and demultiplexed The configuration uses an optical demultiplexer 17 that multiplexes and outputs a pulse to one output port. Examples of the polarization dispersion compensating means include those shown in FIGS. That is,
According to the present embodiment, it is possible to realize an all-optical TDM-WDM conversion circuit whose operation is not affected by the polarization state of the input signal light.

(Third Embodiment of All-Optical TDM-WDM Conversion Circuit) The third embodiment of the all-optical TDM-WDM conversion circuit has an on / off extinction ratio of each channel of a wavelength division multiplexed signal optical pulse train. It is to improve. The overall configuration is the same as in the first embodiment shown in FIG. The feature of this embodiment lies in the configuration of the optical demultiplexer 17.

FIG. 17 shows a second configuration example of the optical demultiplexer 17. The optical demultiplexer shown in FIG. 15A is an ON / OFF filter using a saturable absorber or the like at each output port of each of the optical bandpass filters 22-1 to 22-N of the optical demultiplexer shown in FIG. / Off extinction ratio improving means (SA) 16 is connected.

In the optical demultiplexer shown in (b), an on / off switch using a saturable absorber or the like is provided at each port between the arrayed waveguide grating 24-1 and the arrayed waveguide grating 24-2. An extinction ratio improving means (SA) 16 is inserted.

[0075]

As described above, the all-optical time-division optical pulse separation circuit of the present invention can simultaneously and simultaneously separate low-order group signal channels constituting a time-division multiplexed signal optical pulse train. As a result, the synchronization between the control system clock and the signal light is greatly facilitated as compared with the configuration in which the optical gate circuits are arranged in series or in parallel. In addition, the present invention can significantly reduce the insertion loss as the circuit configuration is greatly simplified, and reduce the noise figure (NF) of the time division multiplexed optical pulse separation circuit used in the receiving system. Can be. This increases the S / N margin in the entire system, and produces effects such as the total transmission distance and the reliability of the transmission system.

In the all-optical time-division optical pulse separation circuit of the present invention, the time-division multiplexed signal optical pulse train is separated into N low-order group signal channels, and simultaneously converted into each wavelength of the chirped control optical pulse. Is done. Therefore, by outputting the low-order group signal channels without separation, the all-optical type T
It can function as a DM-WDM conversion circuit.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment of an all-optical time division optical pulse separation circuit of the present invention.

FIG. 2 is a diagram showing a positional relationship between a signal light pulse and a control light pulse on a time axis.

FIG. 3 is a diagram illustrating an optical frequency shift induced in a control light pulse by cross-phase modulation of a Gaussian light pulse.

FIG. 4 is a diagram showing a time-resolved spectral spectrum and an optical spectrum intensity distribution of a control light pulse.

FIG. 5 is a diagram showing a positional relationship between a time-division multiplexed signal light pulse train “11101” and a control light pulse on a time axis.

FIG. 6 is a diagram showing a time-resolved spectral spectrum and an optical spectrum intensity distribution of a control light pulse.

FIG. 7 is a diagram showing a positional relationship on a time axis between a time-division multiplexed signal light pulse train and a control light pulse in the all-optical time-division light pulse separation circuit of the present invention.

FIG. 8 is a diagram showing a configuration example of an optical demultiplexer 15 having one input and N outputs.

FIG. 9 is a diagram showing a first configuration example of a control light source 13 that generates a control light pulse train having linear chirping.

FIG. 10 is a diagram showing a second configuration example of the control light source 13 that generates a control light pulse train having linear chirping.

FIG. 11 is a diagram showing a simulation result by numerical calculation of the all-optical time division optical pulse separation circuit of the present invention.

FIG. 12 is a diagram showing a simulation result by numerical calculation of the all-optical time-division optical pulse separation circuit of the present invention.

FIG. 13 is a diagram showing a configuration of a second embodiment of the all-optical time division optical pulse separation circuit of the present invention.

FIG. 14 is a diagram showing a configuration of a first embodiment of the all-optical TDM-WDM conversion circuit of the present invention.

FIG. 15 is a diagram showing a first configuration example of an optical demultiplexer 17;

FIG. 16 is a diagram showing a positional relationship on a time axis between a time-division multiplexed signal light pulse train and a control light pulse in the all-optical TDM-WDM conversion circuit of the present invention.

FIG. 17 is a diagram showing a second configuration example of the optical demultiplexer 17;

FIG. 18 is a diagram showing a first configuration example of a conventional all-optical time-division optical pulse separation circuit.

FIG. 19 is a diagram showing the operation principle of a first configuration example of a conventional all-optical time-division optical pulse separation circuit.

FIG. 20 is a diagram illustrating a second configuration example of a conventional all-optical time-division optical pulse separation circuit.

FIG. 21 is a diagram showing a third configuration example of a conventional all-optical time-division optical pulse separation circuit.

FIG. 22 is a diagram showing a third configuration example of the control light source 13 that generates a control light pulse train having linear chirping.

FIG. 23 is a diagram showing a configuration example of a chirp adjusting unit.

FIG. 24 is a diagram showing a configuration example of a polarization dispersion compensating means.

FIG. 25 is a diagram illustrating a configuration example of a polarization dispersion compensation unit.

FIG. 26 is a diagram illustrating a configuration example of a polarization dispersion compensation unit.

FIG. 27 is a diagram showing a second embodiment of the all-optical time division optical pulse separation circuit of the present invention.

FIG. 28 is a diagram showing a power spectrum of a time-division separated signal after optical-electrical conversion.

FIG. 29 is a diagram showing a configuration example of a second embodiment of the all-optical TDM-WDM conversion circuit of the present invention.

[Explanation of symbols]

Reference Signs List 1,12 optical multiplexer 2,15,17 optical demultiplexer 3,14 optical Kerr medium 4 phase change 5 optical frequency shift 6 optical coupler 7,13 control light source 8,11 optical amplifier 9 nonlinear optical medium 16 on / off Extinction ratio improving means (SA) 18 Polarization dispersion compensation means 19 Birefringent optical Kerr medium 21 Optical splitter 22-1 to 22-N Optical bandpass filter 23 Reflection type diffraction grating 24 Array waveguide diffraction grating 31 White pulse generation Optical fiber 32 chirp adjusting means 33 tunable bandpass optical filter 34 normal dispersion optical fiber 50 Fabry-Perot cavity semiconductor mode-locked laser 52 chirped fiber grating 53 optical circulator

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04J 14/08 3/00

Claims (16)

[Claims] 1. A time-division multiplexed signal optical pulse train of an optical frequency νs obtained by time-divisionally multiplexing N (N is an integer of 2 or more) low-order group signal channels is input, adjusted to a predetermined light intensity, and output. An optical intensity adjusting means, having chirping that synchronizes with a low-order group signal channel of the time-division multiplexed signal optical pulse train and monotonically changes in time at an optical frequency different from the optical frequency νs, and has N low-frequency signals; A control light source having a time width including the next-order signal channel and generating a control light pulse having a repetition equal to that of the lower-order signal channel; A pulse train, an optical multiplexing unit that multiplexes the control optical pulse, and an output light of the optical multiplexing unit, and outputs the light according to the presence or absence of a signal optical pulse of each low-order group signal channel of the time-division multiplexed signal optical pulse train. When the control light pulse The control optical pulse corresponding to each of the low-order group signal channels is provided by locally providing cross-phase modulation on the interaxis and inducing an optical frequency shift that compensates for the chirping of the control optical pulse in the optical frequency axis direction. An optical Kerr medium that modulates the optical intensity of the optical frequency ν ₁ , ν ₂ ,..., Ν _N component, and a light transmitted through the optical Kerr medium corresponds to a low-order group signal channel of the time-division multiplexed signal optical pulse train. Optical frequency ν
All-optical time-division optical pulse separation circuit, comprising: an optical demultiplexer for demultiplexing control optical pulses of ₁ , ν ₂ ,..., Ν _N and outputting the demultiplexed control pulses to ports corresponding to respective optical frequencies. . 2. The all-optical time-division optical pulse separation circuit according to claim 1, wherein said light intensity adjusting means is configured such that the time-division multiplexed signal optical pulse train in the optical Kerr medium applies cross-phase modulation to the control optical pulse. An all-optical time-division optical pulse separation circuit, which is an optical amplification means for amplifying a time-division multiplexed signal optical pulse train so that the optical intensity becomes sufficient. 3. The all-optical time-division optical pulse separation circuit according to claim 1, wherein the optical Kerr medium has a positive non-linear refractive index, and the control optical pulse has an optical frequency from the leading end to the trailing end of the pulse. An all-optical time-division optical pulse separation circuit having a down-chirp monotonically decreasing. 4. The all-optical time-division optical pulse separation circuit according to claim 1, wherein the optical Kerr medium has a negative nonlinear refractive index, and the control optical pulse has an optical frequency from the leading end to the trailing end of the pulse. An all-optical time-division optical pulse separation circuit characterized by having a monotonically increasing up-chirp. 5. An all-optical time-division optical pulse separation circuit according to claim 1, wherein the optical Kerr medium has birefringence and compensates for polarization dispersion between two orthogonal main axes. An all-optical time-division optical pulse separation, wherein the control light has a polarization in which polarization components in two orthogonal principal axes of the optical Kerr medium having birefringence have the same intensity. circuit. 6. A time-division multiplexed signal optical pulse train of an optical frequency vs obtained by time-divisionally multiplexing N (N is an integer of 2 or more) low-order group signal channels is input, adjusted to a predetermined light intensity, and output. An optical intensity adjusting means, having chirping that synchronizes with a low-order group signal channel of the time-division multiplexed signal optical pulse train and monotonically changes in time at an optical frequency different from the optical frequency νs, and has N low-frequency signals; A control light source having a time width including the next-order signal channel and generating a control light pulse having a repetition equal to that of the lower-order signal channel; and a time-division multiplexed signal light whose light intensity has been adjusted by the light intensity adjusting means. A pulse train, an optical multiplexing unit that multiplexes the control optical pulse, and an output light of the optical multiplexing unit, and outputs the light according to the presence or absence of a signal optical pulse of each low-order group signal channel of the time-division multiplexed signal optical pulse train. When the control light pulse The control optical pulse corresponding to each of the low-order group signal channels is provided by locally providing cross-phase modulation on the interaxis and inducing an optical frequency shift that compensates for the chirping of the control optical pulse in the optical frequency axis direction. An optical Kerr medium that modulates the optical intensity of the optical frequency ν ₁ , ν ₂ ,..., Ν _N component; and a time-division multiplexed signal optical pulse train of the optical frequency νs and an optical frequency ν ₁ , ν ₂ ,…, ν _N
An optical demultiplexing means for demultiplexing the control optical pulse train, and outputting the control optical pulse train as a wavelength division multiplexed signal optical pulse train instead of the time division multiplexed signal optical pulse train. WDM conversion circuit. 7. The all-optical TDM-WDM according to claim 6.
In the conversion circuit, the light intensity adjusting means amplifies the time-division multiplexed signal light pulse train in the optical Kerr medium such that the time-division multiplexed signal light pulse train has sufficient light intensity to give cross-phase modulation to the control light pulse. All-optical TDM- characterized by being optical amplification means
WDM conversion circuit. 8. The all-optical TDM-WDM according to claim 6,
In the conversion circuit, the optical Kerr medium has a positive nonlinear refractive index, and the control optical pulse has a down chirp in which the optical frequency monotonously decreases from the leading end to the trailing end of the pulse.
-WDM conversion circuit. 9. The all-optical TDM-WDM according to claim 6,
In the conversion circuit, the optical Kerr medium has a negative nonlinear refractive index, and the control light pulse has an up-chirp whose optical frequency monotonically increases from the leading end to the trailing end of the pulse.
-WDM conversion circuit. 10. The all-optical TDM-WD according to claim 6.
In the M conversion circuit, the optical Kerr medium has birefringence, and includes a polarization dispersion compensating means for compensating polarization dispersion between two orthogonal main axes, and the control light is the optical Kerr medium having birefringence. 2. The all-optical TDM-WDM conversion circuit, wherein the two orthogonal polarization components in the main axis direction have polarizations having the same intensity. 11. The all-optical time-division optical pulse separation circuit according to claim 5, wherein the polarization dispersion compensating means is arranged so that two principal axes of the optical Kerr medium having equal length birefringence are orthogonal to each other. An all-optical time-division optical pulse separation circuit characterized by having a cascade connection configuration. 12. The all-optical TDM-W according to claim 10.
In the DM conversion circuit, the polarization dispersion compensating means has a configuration in which two optical Kerr media having equal-length birefringence are connected in cascade such that their main axes are orthogonal to each other. WDM conversion circuit. 13. The all-optical time-division optical pulse separation circuit according to claim 5, wherein the polarization dispersion compensating means includes two optical Kerr media having equal length birefringence, and a λ / 2 plate interposed therebetween. An all-optical time-division optical pulse separation circuit, wherein the all-optical type time-division optical pulse separation circuit is configured to be cascade-connected with each other. 14. The all-optical TDM-W according to claim 10.
In the DM conversion circuit, the polarization dispersion compensator has a configuration in which two optical Kerr media having birefringence of equal length are connected in cascade with a λ / 2 plate interposed therebetween. TDM-WDM conversion circuit. 15. The all-optical time division optical pulse separation circuit according to claim 5, wherein the polarization dispersion compensating means rotates two equal-length birefringent optical Kerr media by 90 degrees Faraday rotation therebetween. An all-optical time-division optical pulse separation circuit having a cascade-connected configuration with a child interposed therebetween. 16. The all-optical TDM-W according to claim 10.
In the DM conversion circuit, the polarization dispersion compensating means has a configuration in which two optical Kerr media having birefringence of equal length are connected in cascade with a 90-degree Faraday rotator interposed therebetween. Type TDM-WD
M conversion circuit.