JPH08110538A - Optical parametric circuit - Google Patents

Abstract

(57) [Abstract] [Purpose] To realize an optical parametric circuit that separates strong pumping light, four-wave mixing light, and signal light into different ports. [Structure] An optical nonlinear medium that induces a third-order optical parametric effect, a 2-input 2-output optical coupler, a first optical waveguide having a length L ₁ and a propagation constant K ₁ (ω), and a length L ₂ , a second optical waveguide having a propagation constant K ₂ (ω), and the length and the propagation constant of each optical waveguide have a predetermined relationship,
Light with a carrier angular frequency ω _s enters from the input port of
When the light having the carrier angular frequencies ω _p1 and ω _p2 is incident from the second input port, the light having the carrier angular frequency ω _s amplified from the first input port of the optical coupler and the carrier angular frequency ω _f (= ω _p1 + ω _p2 −ω _s ) is emitted and the carrier angular frequencies ω _p1 and ω _p2 are output from the second input port of the optical coupler.
Emits light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention utilizes the third-order optical parametric effect induced in an optical nonlinear medium to amplify an optical signal, all-optical switching (optical pulse demultiplexing), wavelength conversion, and phase conjugation. The present invention relates to an optical parametric circuit used as each means of light generation (spectrum inversion).

[0002]

2. Description of the Related Art FIG. 12 shows the configuration of a conventional optical parametric circuit. In the figure, a signal light S (carrier angular frequency ω _s ) and pumping lights P ₁ and P ₂ (carrier angular frequencies ω _p1 and ω
_{The p2} ) is coupled by the optical multiplexer 11, and simultaneously input to the optical nonlinear medium 12 and propagated to induce a third-order optical parametric effect. Then, the signal light S is amplified and the four-wave mixing light F having the carrier angular frequency ω _f is generated by the four-light mixing process. Here, the signal light S, the pump light P ₁ ,
P ₂ , the carrier angular frequencies ω _s , ω _{p1 of} the four-wave mixed light F,
The relationship between ω _p2 and ω _f is ω _s + ω _f = ω _p1 + ω _{p2 according} to the energy conservation law.

In the conventional configuration shown in FIG. 12, all of the amplified signal light S ′, the pumping lights P ₁ and P ₂ , and the four-wave mixed light F are emitted from the optical nonlinear medium 12 in the same direction so that they overlap each other. An optical filter was indispensable for extracting desired light. For example, in order to extract only the four-wave mixed light F, the wavelength filter 13 that passes only the light having the carrier angular frequency ω _f is used.

[0004]

By the way, the excitation light P ₁ ,
The light intensity of P ₂ is usually higher than the light intensity of the amplified signal light S ′ or the four-wave mixing light F. Therefore, the wavelength filter 13 needs to have a high isolation that can largely suppress the excitation light. In particular, when the wavelength difference from the pumping light is small, it is difficult to sufficiently suppress the pumping light with a single-stage wavelength filter, and it is inevitable to increase loss and complicate the configuration by combining multiple stages. .

An object of the present invention is to provide an optical parametric circuit capable of separating strong pumping light, four-wave mixing light and signal light into different ports.

[0006]

According to the optical parametric circuit of claim 1, light having carrier angular frequencies ω _s , ω _p1 , ω _p2 , and ω _f having a relationship of ω _s + ω _f = ω _p1 + ω _p2 is interposed. An optical nonlinear medium that induces a third-order optical parametric effect, and a 2-input 2-output optical coupler that splits lights of carrier angular frequencies ω _s , ω _p1 , ω _p2 , and ω _f with equal intensity and equal polarization, respectively. , A first optical waveguide having a length L ₁ and a propagation constant K ₁ (ω) coupling the first output port of the optical coupler and one end of the optical nonlinear medium, and the second output port of the optical coupler. Length L ₂ for coupling with the other end of the optical nonlinear medium, propagation constant K ₂ (ω)
And a second optical waveguide, the length and propagation constant of the first optical waveguide and the second optical waveguide are an integer n and an allowable error α
When (0 ≦ α <1/2), {K ₂ (ω _s ) + K ₂ (ω _f ) −K ₂ (ω _p1 ) −K ₂ (ω _p2 )} L ₂ =
{K ₁ (ω _s ) + K ₁ (ω _f ) −K ₁ (ω _p1 ) −K ₁ (ω _p2 )} L ₁ +
Light having a carrier angular frequency ω _s is input from the first input port of the optical coupler and light having carrier angular frequencies ω _p1 and ω _p2 is input from the second input port. When incident, the light of carrier angular frequency ω _s amplified from the first input port of the optical coupler and the light of carrier angular frequency ω _f (= ω _p1 + ω _p2 − ω _s ) generated in the optical nonlinear medium From the second input port of the optical coupler, and the carrier angular frequencies ω _p1 , ω
_{Emit p2} light.

In the optical parametric circuit of claim 2, the optical nonlinear medium, the optical coupler, the first optical waveguide and the second optical waveguide have polarization maintaining properties. An optical parametric circuit according to a third aspect of the invention has means for blocking light having carrier angular frequencies ω _p1 and ω _p2 emitted from the second input port of the optical coupler.

According to another aspect of the optical parametric circuit of the present invention, the carrier angular frequency ω incident on the first input port of the optical coupler is ω.
comprises a light _s, the means for separating the light of the first carrier angular frequency omega _s emitted from the input port, omega _f.

An optical parametric circuit according to a fifth aspect of the present invention comprises means for separating the light having the carrier angular frequency ω _s emitted from the first input port of the optical coupler from the light having the carrier angular frequency ω _f .

An optical parametric circuit according to a sixth aspect of the present invention comprises means for suppressing light having carrier angular frequencies ω _p1 and ω _p2 emitted from the first input port of the optical coupler. An optical parametric circuit according to a seventh aspect is provided with a plurality of the optical parametric circuits according to the fourth aspect, and means for allowing only the light having the carrier angular frequency ω _f to pass through the input / output of each stage of the optical parametric circuit and the carrier angular frequency ω. _s are connected in cascade through alternating means for passing only light.

An optical parametric circuit according to an eighth aspect comprises a plurality of the optical parametric circuits according to the fourth aspect, and an optical parametric circuit of each stage outputs the carrier angular frequency ω.
The light of _f is separated, and the light of carrier angular frequency ω _s is connected in cascade via a means for sending the light to the next stage.

An optical parametric circuit according to a ninth aspect comprises means for connecting a plurality of the optical parametric circuits according to the fourth aspect in a cascade, and separating light having a carrier angular frequency ω _f from the output of the final stage optical parametric circuit. Prepare

[0013]

FIG. 1 shows the basic configuration of the optical parametric circuit of the present invention. In the figure, the optical nonlinear medium 12 is inserted into an optical waveguide that connects the ports of the 2 × 2 optical coupler 20. Here, the length of the optical waveguide 21 connecting the port and the optical nonlinear medium 12 is L ₁ , and the propagation constant is K ₁ (ω).
Let L _{2 be} the length of the optical waveguide 22 that connects the port and the optical nonlinear medium 12, and let K ₂ (ω) be the propagation constant. The optical coupler 20 has carrier angular frequencies ω _s , ω _p1 , ω _p2 , and ω _f.
Has the characteristic of splitting the light of the same intensity and polarization.

The signal light S having the carrier angular frequency ω _s is incident from the port of the optical coupler 20 and is branched to the port with equal intensity and equal polarization. However,
The signal light S emitted from the port which is a cross port with respect to the port is 90 degrees in phase with the signal light S emitted from the port which is a through port. Therefore, the complex electric field amplitude of the signal light S at the port is A
When _s, complex electric field amplitude of the signal light S at port becomes _{A s exp (-iπ / 2)} .

The pumping lights P ₁ and P ₂ having the carrier angular frequencies ω _p1 and ω _p2 are incident from the port of the optical coupler 20,
Each is split into ports with equal intensity and polarization. However, the pumping light P _1, P ₂ emitted from the port to which the cross port with respect to port, and the phase of the light is delayed by 90 degrees with respect to excitation light P _1, P ₂ emitted from the port to which the through port . Therefore, when the complex electric field amplitude of the pumping light P _1, P ₂ at the port and A _p1, A _p2, complex electric field amplitude of the pumping light P _1, P ₂ in the port _{A p1 exp (-iπ / 2)} , A p2 exp (-iπ / 2).

As described above, the signal light S and the pumping lights P ₁ and P ₂ branched to the port of the optical coupler 20 are supplied to the optical waveguide 2.
The light propagates clockwise in the order of 1 → optical nonlinear medium 12 → optical waveguide 22 → port. Here, from the port to the optical waveguide 21
Complex electric field amplitude of the clockwise signal light S incident on the optical nonlinear medium 12 via the A _sR and excitation light P _1, P ₂ of the complex electric field amplitude _A p1R, A p2R _{is, A sR = A s exp (} - iK ₁ (ω _s ) L ₁ ) ... (1) A _p1R = A _p1 exp (−iK ₁ (ω _p1 ) L ₁ −iπ / 2) (2) A _p2R = A _p2 exp (−iK ₁ (ω _p2 ) L ₁ −iπ / 2) (3)

On the other hand, the signal light S and the pumping lights P ₁ and P ₂ branched to the port of the optical coupler 20 propagate counterclockwise in the order of the optical waveguide 22 → optical nonlinear medium 12 → optical waveguide 21 → port. Here, the complex electric field amplitude A _sL of the counterclockwise signal light S and the complex electric field amplitude A of the pumping lights P ₁ and P ₂ incident on the optical nonlinear medium 12 from the port via the optical waveguide 22.
_p1L, A _{p2L is, A sL = A s exp (} -iK 2 (ω s) L 2 -iπ / 2) ... (4) A p1L = A p1 exp (-iK 2 (ω p1) L 2) ... ( 5) A _p2L = A _p2 exp (−iK ₂ (ω _p2 ) L ₂ ) ... (6)

In the optical nonlinear medium 12, due to the third-order optical parametric effect induced by the signal light S and the pumping lights P ₁ and P ₂ propagating simultaneously in the clockwise and counterclockwise directions, respectively,
The signal light S is amplified and the carrier angular frequency ω _f (= ω _p1 +
The four-wave mixing light F of ω _p2 −ω _s ) is generated. The right-handed component and the left-handed component are incident on the optical coupler 20 again and interfere with each other.

However, the signal light S (amplified signal light S ')
And the pumping lights P ₁ and P ₂ undergo a phase change due to wavelength dispersion in the optical nonlinear medium 12 and the optical waveguides 21 and 22, and a phase change due to a nonlinear effect (self-phase modulation, mutual phase modulation) in the optical nonlinear medium 12. However, there is no phase difference between clockwise and counterclockwise. Therefore, this circuit is
It operates as a so-called optical loop mirror for (amplified signal light S ′) and pumping lights P ₁ , P ₂ (DBMortim
ore, "Fiber loop reflectors", IEEE Journal of Lightw
ave Technology, vol.6, pp.1217-1224, 1988), the amplified signal light S'is emitted to the port and the pump lights P ₁ and P ₂ are emitted to the port 100% respectively, and the amplified signal light S'is emitted.
And the excitation lights P ₁ and P ₂ can be completely separated.

On the other hand, the complex electric field amplitude A of the clockwise signal light S represented by the equations (1), (2) and (3) and the clockwise four-wave mixing light F generated from the pumping lights P ₁ and P _{2 fR} is A _fR = cA _sR ^* A _p1R A _p2R = cA _s ^* A _p1 A _p2 exp [i (K ₁ (ω _s ) −K ₁ (ω _p1 ) −K ₁ (ω _p2 )) L ₁ −iπ ]… (7) Further, the complex electric field amplitude A _fL of the counterclockwise signal light S and the counterclockwise four-wave mixing light F generated from the pumping lights P ₁ and P _{2 represented} by the equations (4), (5), and (6) is A _fL = cA _sL ^* A _p1L A _p2L = cA _s ^* A _p1 A _p2 exp [i (K ₂ (ω _s ) −K ₂ (ω _p1 ) −K ₂ (ω _p2 )) L ₂ + iπ / 2] ( 8) Note that c is a proportional constant.

The complex electric field amplitudes A ₄ and A ₃ when the clockwise and counterclockwise four-wave mixing light F reaches the port via the optical waveguides 22 and 21, respectively, are A ₄ = A _fR exp (- iK ₂ (ω _f ) L ₂ ) = cA _s ^* A _p1 A _p2 exp [−i (K ₁ (ω _f ) L ₁ + K ₂ (ω _f ) L ₂ )] exp (iΔK ₁ L ₁ −i π) ... (9) A ₃ = A _fL exp (−iK ₁ (ω _f ) L ₁ ) = cA _s ^* A _p1 A _p2 exp [−i (K ₁ (ω _f ) L ₁ + K ₂ (ω _f ) L ₂ ). ] exp (iΔK ₂ L ₂ + iπ / 2) (10) In addition, ΔK ₁ = K ₁ (ω _s ) + K ₁ (ω _f ) −K ₁ (ω _p1 ) −K ₁ (ω _p2 ) ... (11) ΔK ₂ = K ₂ (ω _s ) + K ₂ (ω _f ). -K is a _{2 (ω p1) -K 2 (} ω p2) ... (12).

In the optical coupler 20, the clockwise and counterclockwise 4
Wave mixing light F interfere, port 4 complex electric field amplitude A ₁ of the wave mixing light F, A ₂ emitted in, _{is, A 1 αA 3 + A 4} exp (-iπ / 2) α exp (iΔK 2 L ₂ ) + exp (iΔK ₁ L ₁ ) ... (13) A ₂ ∝A ₃ exp (−iπ / 2) + A ₄ ∝exp (iΔK ₂ L ₂ ) −exp (iΔK ₁ L ₁ ) ... (14) It Therefore, when the optical waveguides 21 and 22 satisfy the condition of ΔK ₂ L ₂ = ΔK ₁ L ₁ + 2nπ (n is an integer) (15), the four-wave mixing light F is used as a port.
It can be emitted 100% and can be completely separated from the excitation lights P ₁ and P ₂ emitted to the port.

When a predetermined allowable error α (0 ≦ α <1/2) is recognized in the condition shown in the equation (15), ΔK ₂ L ₂ = ΔK ₁ L ₁ + (2n ± α) π (n is Integer)… (16) In that case, although the level of the four-wave mixed light F emitted to the port is lowered according to the tolerance α, the isolation with respect to the excitation lights P ₁ and P ₂ emitted to the port is not affected, so that it is practical. There is no problem above.

By constructing the optical parametric circuit as described above, it is possible to separate the amplified signal light S ′ and the pumping lights P ₁ and P ₂ without using a wavelength separating means such as a wavelength filter. . Furthermore, by using the optical waveguides 21 and 22 that satisfy the conditions shown in the equations (15) and (16),
The generated four-wave mixing light F and the excitation lights P ₁ and P ₂ can be separated. Note that the noise component contained in the pumping lights P ₁ and P ₂ is also emitted from the port together with the pumping lights P ₁ and P ₂ , so that it does not mix into the signal light S ′ and the four-wave mixing light F.

According to a second aspect of the present invention, each part is of a polarization maintaining type, and a third aspect is for preventing the pumping light from returning.
According to a fourth aspect of the present invention, input / output light is separated.
Is configured as an optical amplifier or a wavelength conversion circuit, and claim 6 is a configuration for suppressing light having carrier angular frequencies ω _p1 and ω _p2 mixed in light having carrier angular frequencies ω _s and ω _f , Claims 7 and 8 constitute an optical pulse demultiplexing circuit, and claim 9 constitutes an optical pulse multiplexing circuit. Each function will be described in detail in the following second to eleventh embodiments.

[0026]

FIG. 2 shows the configuration of the first embodiment of the present invention.
The feature of the present embodiment is that in the basic configuration shown in FIG. 1, the degenerate pump light, that is, the carrier angular frequency is ω _p = ω _p1 =
This is where the excitation light P of ω _p2 is used.

In this embodiment, when the signal light S having the carrier angular frequency ω _s is incident from the port of the optical coupler 20 and the pump light P having the carrier angular frequency ω _p is incident from the port, the carrier in the optical nonlinear medium 12 is Angular frequency ω _f (= 2ω _p −
The four-wave mixed light F of ω _s ) is generated. The four-wave mixed light F and the amplified signal light S ′ are emitted from the port of the optical coupler 20, and the excitation light P is emitted from the port.

In an actual optical parametric circuit,
Since the degenerate pumping light P is often used as in the present embodiment, the degenerate pumping light P is used in the following embodiments.

FIG. 3 shows the configuration of the second embodiment of the present invention. The feature of this embodiment is that each part of the basic configuration shown in FIG. 1 is a polarization maintaining type, a polarization maintaining type optical coupler 23, a polarization maintaining type optical nonlinear medium 24, and a polarization maintaining type optical waveguide 25. , 26
Is used (Claim 2).

The polarization crosstalk in the optical parametric circuit is caused by the pumping light P for the signal light S and the four-wave mixing light F.
Cause deterioration of isolation. Therefore, by making each part a polarization maintaining type, polarization crosstalk in the circuit is suppressed and the isolation of the pumping light P with respect to the signal light S and the four-wave mixing light F is improved. In addition, also in the embodiments described below, the polarization crosstalk in the circuit can be suppressed by making each part a polarization maintaining type.

FIG. 4 shows the configuration of the third embodiment of the present invention. The feature of this embodiment is that in the basic configuration shown in FIG.
The pumping light P emitted from the port of the optical coupler 20 is blocked (claim 3).

In the optical parametric circuit of the present invention, the amplified signal light S'and pumping light P are returned to the input ports respectively. Therefore, the particularly strong excitation light P may adversely affect the excitation light source. Therefore, the optical isolator 27 is connected to the port of the optical coupler 20 where the pumping light P enters.
Is arranged to block the excitation light P emitted from the port. An optical circulator may be used instead of the optical isolator 27.

FIG. 5 shows the configuration of the fourth embodiment of the present invention. The feature of this embodiment is that in the basic configuration shown in FIG.
The signal light S incident on the port of the optical coupler 20 is separated from the amplified signal light S ′ and the four-wave mixing light F emitted from the port (claim 4).

In the optical parametric circuit of the present invention, the incoming signal light S and the outgoing signal light S ′ and the four-wave mixing light F pass through the same port of the optical coupler 20, so they are separated. Requires configuration. Therefore, an optical circulator 28 is arranged at the port of the optical coupler 20,
The signal light S is separated from the amplified signal light S ′ and the four-wave mixed light F.

FIG. 6 shows the configuration of the fifth embodiment of the present invention. The feature of this embodiment is that the optical parametric circuit is configured as an optical amplifier (claim 5).

In the present embodiment, in addition to the configuration of the fourth embodiment, a wavelength filter 29 that passes only the amplified signal light S '(carrier angular frequency ω _s ) is used. As the pumping light P (carrier angular frequency ω _p ), CW (continuous wave) pumping light is used or a pumping light pulse train synchronized with the signal light S is used. As a result, when the signal light S is incident on the port of the optical coupler 20 via the optical circulator 28, the amplified signal light S ′ can be extracted from the port via the optical circulator 28 and the wavelength filter 29.

It is applied to the optical waveguides 21 and 22 (1
The conditions of the expressions (5) and (16) relate to the four-wave mixing light F and do not affect the isolation between the amplified signal light S ′ and the pump light P. Therefore, when functioning as an optical amplifier of the signal light S as in the present embodiment, (15), (1
The condition of equation (6) is unnecessary. Also, in equation (16), α =
When it is set to 1, the four-wave mixed light F having the carrier angular frequency ω _f is emitted from the port of the optical coupler 20, so that the wavelength filter 29 is unnecessary.

FIG. 7 shows the configuration of the sixth embodiment of the present invention. The feature of this embodiment resides in that the optical parametric circuit is configured as a wavelength conversion circuit (claim 5).

In this embodiment, in addition to the structure of the fourth embodiment, a wavelength filter 13 that allows only four-wave mixed light F (carrier angular frequency ω _f ) to pass is used. Also, the excitation light P
As the (carrier angular frequency ω _p ), CW (continuous wave) pumping light is used, or a pumping light pulse train synchronized with the signal light S is used. As a result, when the signal light S (carrier angular frequency ω _s ) is incident on the port of the optical coupler 20 via the optical circulator 28, the optical circulator 2 from the port.
8. The four-wave mixed light F can be extracted via the wavelength filter 13. The carrier angular frequency ω _f (= 2ω _p −ω _s ) of the four-wave mixed light F can be tuned by changing the carrier angular frequency ω _p of the pumping light P.

Also, instead of the optical circulator 28 and the wavelength filter 13, an optical demultiplexer for separating the carrier angular frequencies ω _s and ω _f can be used to separate and extract only the four-wave mixed light F. .

The configuration of the present embodiment is such that when a pumping light pulse having a pulse width sufficiently wider than that of the CW pumping light or the signal light S is used, the input signal light spectrum is inverted with respect to the carrier angular frequency ω _p of the pumping light. It can be operated as a so-called spectrum inverting circuit (phase conjugate mirror) that generates four-wave mixed light having a symmetrical spectrum. This makes it possible to compensate for waveform broadening due to chromatic dispersion or spectrum broadening due to self-phase modulation (Watanabe
et al., "Compensation of chromatic dispersion in as
ingle-mode fiber by optical phase conjugation ", I
EEE Photonics Technology Letters, vol.5, pp.92-95,
1993).

In the fifth and sixth embodiments, the pumping light P is separated from the signal light S ′ amplified by the optical coupler 20 or the four-wave mixing light F, but the pumping light P enters the port. Even if it leaks, it can be removed by the wavelength filters 29 and 13, so that the isolation with respect to the excitation light P can be further improved. Also, a wavelength filter that suppresses the excitation light P may be provided independently. Also, the second
In the case of the polarization maintaining configuration as in the embodiment, the isolation of the pumping light P can be further improved by using the polarizer together to suppress the leaking pumping light P due to the polarization crosstalk. (Claim 6).

FIG. 8 shows the configuration of the seventh embodiment of the present invention. The feature of the present embodiment is that a two-input one-output optical gate circuit (optical AN is provided with the same configuration as the wavelength conversion circuit of the sixth embodiment.
D circuit).

[0044] In this embodiment, the signal light S of the carrier angular frequency omega _s, 'an input light pulse S _in, S' S and _in, the excitation light P of the carrier angular frequency omega _p and the gate light pulse G, carrier angle The four-wave mixed light F having the frequency ω _f (= 2ω _p −ω _s ) is used as the output light pulse S _out . When the input optical pulse S _in and the gate optical pulse G are incident so as to overlap each other in the optical nonlinear medium 12 (time slot t ₂ ), the output optical pulse S in
_out occurs. This output light pulse S _out is taken out through the wavelength filter 13 that passes only the carrier angular frequency ω _f .

FIG. 9 shows the configuration of the eighth embodiment of the present invention. The feature of this embodiment is that an optical pulse demultiplexing circuit for demultiplexing the time-division multiplexed optical pulse signal is realized by connecting the optical gate circuits of the seventh embodiment in a plurality of stages (claim 7).

In the present embodiment, _in response to the input optical pulse S _in having the carrier angular frequency ω _s , the gate optical pulse G ₁ having the carrier angular frequency ω _p is input to the first stage optical gate circuit, and its time slot ( carrier angular frequency ω _f (= t ₂ , t ₄ )
The output optical pulse S _out1 of 2ω _p −ω _s ) is output. As a result, first, the two channels of the time slot (t ₂ , t ₄ ) are separated. Next, with _{respect to} the output optical pulse S _out1 of the carrier angular frequency ω _f , the gate optical pulse G ₂ of the carrier angular frequency ω _p is input to the second stage optical gate circuit, and the carrier is input to the time slot (t ₄ ). Angular frequency ω _s (= 2ω _p −ω _f )
The output optical pulse S _out2 is output. As a result, one channel of the time slot (t ₄ ) in which both the gate optical pulses G ₁ and G ₂ are finally turned on is separated.

In the first-stage optical gate circuit, an output optical pulse (four-wave mixing light) S _out1 having a carrier angular frequency ω _f is generated from an input optical pulse S _in having a carrier angular frequency ω _s . In the second stage optical gate circuit, the carrier angular frequency ω _{s is changed} from the output optical pulse S _out1 having the carrier angular frequency ω _f.
Output light pulse (4 light wave mixed light) S _out2 is generated. As a result, the output light pulse S _out2 has the same wavelength as the input light pulse S _in . Therefore, the wavelength filter 1 that allows only the carrier angular frequency ω _f to pass through the first-stage optical gate circuit.
3 is used, and a wavelength filter 29 that passes only the carrier angular frequency ω _s is used in the second-stage optical gate circuit.

FIG. 10 shows the configuration of the ninth embodiment of the present invention. The feature of the present embodiment is that optical wavelength demultiplexers 30-1 and 30- for separating carrier angular frequencies ω _s and ω _f are used instead of the wavelength filters 13 and 29 used in the optical pulse separation circuit of the eighth embodiment.
2 is used (claim 8).

In the present embodiment, for the input optical pulse S _in having the carrier angular frequency ω _s , the gate optical pulse G ₁ having the carrier angular frequency ω _p is input to the first stage optical gate circuit, and its time slot ( carrier angular frequency ω _f (= t ₂ , t ₄ )
2ω _p −ω _s ) output optical pulse S _out1 is generated. The output optical pulse S _out1 is demultiplexed by the optical demultiplexer 30-1 to separate the two channels of the time slot (t ₂ , t ₄ ).

[0050] At this time, the other port of the optical demultiplexer 30-1, an input light pulse S _'in the amplified carrier angular frequency omega _s is output and input into the next stage of the optical gate circuit. In the second stage optical gate circuit, the carrier angular frequency ω _p
Input gate optical pulse G ₂ and generate an output optical pulse S _out2 of carrier angular frequency ω _f (= 2ω _p −ω _s ) in the time slot (t ₁ , t ₃ ). This output light pulse S
By demultiplexing _out2 with the optical demultiplexer 30-2, the two channels of the time slots (t ₁ , t ₃ ) are separated.

At this time, the input optical pulse S " _in having the amplified carrier angular frequency ω _s is output to the other port of the optical demultiplexer 30-2. Therefore, in this embodiment, the optical demultiplexer is used. By connecting a plurality of optical gate circuits via 30, a predetermined channel can be separated any number of times, and the input optical pulse S _in can be amplified and output.

FIG. 11 shows the configuration of the tenth embodiment of the present invention. The feature of the present embodiment is that an optical pulse multiplexing circuit for multiplexing the input optical pulses S _in1 and S _in2 is realized by the same configuration as the optical pulse demultiplexing circuit of the eighth embodiment (claim 9).

In this embodiment, the optical circulator 28-is connected to the port of the optical coupler 20-1 of the first-stage optical gate circuit.
A clock pulse C having a carrier angular frequency ω _s is input via 1. Further, the input optical pulse S _in1 having the carrier angular frequency ω _p is input to the port. At this time, in the optical nonlinear medium 12-1, the carrier angular frequency ω _f (= 2ω _p −) in the time slot (t ₂ , t ₄ ) of the first input optical pulse S _in1.
An output light pulse (four-wave mixing light) S _{out1 of} ω _s ) is generated and emitted from the port together with the clock pulse C ′ amplified in the time slot (t ₂ , t ₄ ).

The clock pulse C'and the output light pulse S
_out1 is _input from the optical circulator 28-1 to the port of the optical coupler 20-2 via the optical circulator 28-2 of the second stage optical gate circuit. Further, the input optical pulse S _in2 having the carrier angular frequency ω _p is input to the port. At this time, in the optical nonlinear medium 12-2, in the time slot (t ₁ , t ₃ ) of the second input optical pulse S _in2 , the output optical pulse (four optical waves) of the carrier angular frequency ω _f (= 2ω _p −ω _s ). Mixed light) S _out2 is generated and the optical pulse S output from the port
It is emitted together with _out1 and the clock pulse C ″ amplified in the time slot (t ₁ , t ₃ ).

The wavelength filter 13 blocks this clock pulse C ″ and outputs the output optical pulse S of the carrier angular frequency ω _f.
Only _out1 and S _out2 are passed. In this way, the output optical pulses S _out1 and S _{out2 of} the carrier angular frequency ω _f in which the input optical pulses S _in1 and S _in2 of the carrier angular frequency ω _s are multiplexed.
Is obtained.

[0056]

As described above, in the optical parametric circuit of the present invention, the signal light S and the pumping lights P ₁ and P ₂ are coupled without using the optical multiplexing / demultiplexing means such as the wavelength filter and further amplified. The signal light S ′ and the excitation lights P ₁ and P ₂ can be separated and taken out. Furthermore, by using an optical waveguide that satisfies a predetermined condition, it is possible to separate the generated four-wave mixing light F and the excitation lights P ₁ and P ₂ . Since the noise component included in the pumping light is emitted together with the pumping light, unnecessary noise is not superimposed on the signal light and the four-wave mixing light.

Therefore, by using the optical parametric circuit of the present invention, amplification of optical signals, all-optical switching (optical pulse demultiplexing), wavelength conversion, and generation of phase conjugate light can be achieved without being affected by high-level pumping light. (Spectrum inversion)
Becomes possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of an optical parametric circuit of the present invention.

FIG. 2 is a block diagram showing a configuration of a first embodiment (degenerate pump light) of the present invention.

FIG. 3 is a block diagram showing the configuration of a second embodiment (polarization maintaining type) of the present invention.

FIG. 4 is a block diagram showing a configuration of a third embodiment (excitation light return blocking) of the present invention.

FIG. 5 is a block diagram showing a configuration of a fourth embodiment (separation of input / output light) of the present invention.

FIG. 6 is a block diagram showing the configuration of a fifth embodiment (optical amplifier) of the present invention.

FIG. 7 is a block diagram showing the configuration of a sixth embodiment (wavelength conversion circuit) of the present invention.

FIG. 8 is a seventh embodiment of the present invention (optical gate circuit (optical AND
FIG. 3 is a block diagram showing the configuration of (circuit)).

FIG. 9 is a block diagram showing the configuration of an eighth embodiment (optical pulse separation circuit) of the present invention.

FIG. 10 is a block diagram showing the configuration of a ninth embodiment (optical pulse separation circuit) of the present invention.

FIG. 11 is a tenth embodiment of the present invention (optical pulse multiplexing circuit).
Block diagram showing the configuration of FIG.

FIG. 12 is a block diagram showing a configuration of a conventional optical parametric circuit.

[Explanation of symbols]

11 Optical Multiplexer 12 Optical Nonlinear Medium 13 Wavelength Filter (ω _f ) 20 Optical Coupler 21, 22 Optical Waveguide 23 Polarization-Maintaining Optical Coupler 24 Polarization-Maintaining Optical Nonlinear Medium 25, 26 Polarization-Maintaining Type Optical waveguide 27 Optical isolator 28 Optical circulator 29 Wavelength filter (ω _s ) 30 Optical demultiplexer

Claims (9)

[Claims] 1. Lights of carrier angular frequencies ω _s , ω _p1 , ω _p2 , and ω _f having a relationship of ω _s + ω _f = ω _p1 + ω _p2 are interposed 3
An optical nonlinear medium that induces the following optical parametric effect, a 2-input 2-output optical coupler that splits light having carrier angular frequencies ω _s , ω _p1 , ω _p2 , and ω _f with equal intensity and equal polarization, respectively. A first optical waveguide having a length L ₁ and a propagation constant K ₁ (ω) coupling the first output port of the optical coupler and one end of the optical nonlinear medium; and a second output of the optical coupler. A second optical waveguide having a length L ₂ and a propagation constant K ₂ (ω) for coupling the port and the other end of the optical nonlinear medium, and the lengths of the first optical waveguide and the second optical waveguide And the propagation constant is an integer n and an allowable error α (0 ≦ α <1/2), {K ₂ (ω _s ) + K ₂ (ω _f ) −K ₂ (ω _p1 ) −K ₂ (ω _p2 )} L ₂ =
{K ₁ (ω _s ) + K ₁ (ω _f ) −K ₁ (ω _p1 ) −K ₁ (ω _p2 )} L ₁ +
Light having a carrier angular frequency ω _s from the first input port of the optical coupler, and light having carrier angular frequencies ω _p1 and ω _p2 from the second input port. Of the carrier angular frequency ω _s amplified from the first input port of the optical coupler.
Of light and the carrier angular frequency ω _f (= ω _p1 + ω _p2 −ω _s ) generated in the optical nonlinear medium are emitted, and the carrier angular frequency ω _p1 from the second input port of the optical coupler,
An optical parametric circuit that emits light of ω _p2 . 2. The optical parametric circuit according to claim 1, wherein the optical nonlinear medium, the optical coupler, the first optical waveguide, and the second optical waveguide have polarization maintaining properties. . 3. The optical parametric circuit according to claim 1, further comprising means for blocking light having carrier angular frequencies ω _p1 and ω _p2 emitted from the second input port of the optical coupler. Optical parametric circuit. 4. The optical parametric circuit according to claim 1, wherein light having a carrier angular frequency ω _s incident on the first input port of the optical coupler and carrier angular frequency ω emitted from the first input port. An optical parametric circuit having means for separating the light of _s and ω _f . 5. The optical parametric circuit according to claim 1, which separates light having a carrier angular frequency ω _s emitted from the first input port of the optical coupler and light having a carrier angular frequency ω _f. An optical parametric circuit characterized by having. 6. The optical parametric circuit according to claim 1, further comprising means for suppressing light having carrier angular frequencies ω _p1 and ω _p2 emitted from the first input port of the optical coupler. Optical parametric circuit to do. 7. A plurality of optical parametric circuits according to claim 4, a means for allowing only the light of carrier angular frequency ω _f to pass through the input and output of each stage of optical parametric circuit, and only the light of carrier angular frequency ω _s . An optical parametric circuit characterized in that it is connected in cascade via means for alternately passing through. 8. A plurality of optical parametric circuits according to claim 4 are provided, light having a carrier angular frequency ω _f is separated from the output of each stage of optical parametric circuits, and light having a carrier angular frequency ω _s is provided to the next stage. An optical parametric circuit characterized in that the optical parametric circuits are connected in cascade via a means for transmitting. 9. A plurality of optical parametric circuits according to claim 4 are connected in cascade, and means for separating the light of the carrier angular frequency ω _f from the output of the final stage optical parametric circuit is provided. Optical parametric circuit.