JPH11194375A - Optical modulating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical modulating device which can obtain stable output light. SOLUTION: A light pulse train S2 is inputted from a control pulse light source 2 to an optical modulator 4, which outputs a pulse pattern S4. The pulse pattern S4 is inputted to a beam splitter 14 in a spatial interference system 10. A light pulse train S1 is inputted from a ultrasonic pulse light source 1 to a beam splitter 7 and transmitted. The transmitted light th1 is made incident on a beam splitter 11 in the spatial interference system 10. The incident transmitted light th1 is branched into two systems of transmitted light th2 and reflected light re4 , which after traveling as optical space parallel lights in the spatial interference system 10 in mutually opposite directions, return to the beam splitter 11 to generate interference lights if1 and if2 . The interference light if1 is passed through the beam splitter 7 and an optical 211 and outputted as an output light S21 and the interference light if2 is passed through an optical filter 22 and outputted as an output light S22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to, for example, optical communication,
The present invention relates to an optical information processing device and an optical modulation device that modulates an optical pulse train used in an optical computer and the like.

[0002]

2. Description of the Related Art Conventionally, techniques in such a field include:
For example, there is one described in the following literature. Literature; IEICE, IEICE Technical Report, LQE96-11 (1996-0
5), Kutsuzawa et al., "Ultra-high-speed optical pulse generation and coding experiments using mode-locked semiconductor lasers", P.61-66. Development is urgent. As elemental technologies constituting a signal pulse light source, stable generation of an ultra-high-speed and ultra-short optical pulse train and a high-speed optical modulation method for modulating this are indispensable.

Various research reports have been made on an ultrashort pulse generation method using a semiconductor laser. Among them, a passively mode-locked semiconductor laser has attracted attention as an ultrafast pulsed light source exceeding terahertz. One of the problems when using a passively mode-locked semiconductor laser in an optical communication system is that the output light has a large jitter. Can be improved. On the other hand, regarding the light modulation method, the current technology
The number of bits of the modulation signal is limited by the speed of the electronic device around the semiconductor laser. Therefore, in order to obtain an ultra-high-speed signal pulse of several hundred gigabits, it is necessary to generate an optical pulse train that can be electrically modulated and multiplex it on the time axis after the modulation. On the other hand, a method has been proposed in which a high-speed optical pulse train is generated in advance, and only one integral channel of the repetition is extracted and modulated in multiple stages. In such a multi-stage modulation system, an ultra-high-speed optical modulator that operates in picoseconds or less is required.

FIG. 2 is a configuration diagram of a conventional light modulation device described in the above-mentioned document. In this optical modulator, the ultrafast pulse light source 1 generates an optical pulse train S1 having a repetition frequency of f (Hz), and the control pulse light source 2 has a repetition frequency of f / N (H
z) (where N is an integer) of the control light pulse S2 is generated. The pulse pattern generator 3 generates a pulse pattern S3 having a repetition frequency f / N, and the control light pulse S2 is modulated by the optical modulator 4 based on the pulse pattern S3 to generate f /
A modulated optical pulse train S4 encoded by N (bits / s) is generated. The optical pulse train S1 and the modulated optical pulse train S4 are
TOAD (Terahertz Optical Asymmetric Demultiplexe)
r) sent to 5. The TOAD 5 is a high-speed optical switch using nonlinearity such as a semiconductor optical amplifier, and the switching operation is controlled by the ON state and the OFF state of the modulated optical pulse train S4. The optical pulse train S1 is
Coupler 5c via circulator 5a and fiber 5b
And is branched into two systems by the coupler 5c. One system includes a nonlinear medium (TWA (Tra) such as a coupler 5c to a fiber 5d, a polarization controller 5e, a fiber 5f, a coupler 5g, a fiber 5h, and a semiconductor optical amplifier.
veling Wave Ampliphier)) The light travels sequentially through 5i, fiber 5j, optical delay unit 5k, and fiber 51, and reaches coupler 5c. The other system proceeds in this loop in the opposite direction. At this time, the difference between the times when the traveling lights CW and CCW traveling in these two directions are affected by the nonlinear medium (TWA) is the gate time of the TOAD5.

That is, the gate time ΔT is represented by ΔT = 2Δx / v, where Δx is the optical distance between the midpoint of the optical path of the loop and the nonlinear medium 5i, and v is the speed of light. The gate time ΔT is different between the input light CW and the input light C.
Since it is determined by the difference 2Δx of the optical distance from the CW to the nonlinear medium 5i, a high-speed switching operation of picoseconds or less is possible in principle. Then, the traveling lights CW and CCW interfere with each other in the optical coupler 5c, and a band-pass filter (hereinafter referred to as B
From 5 m at a repetition frequency f / NHz with the same data pattern as the pulse pattern S3 (this is called PF)
An optical pulse train S5 encoded as positive logic is output, and an optical pulse train S6 encoded at a repetition frequency fHz and a data pattern opposite to the pulse pattern S3 at a repetition frequency of fHz (this is referred to as encoded negative logic) is output from the BPF 6. Is output.

[0006]

However, the conventional optical modulator shown in FIG. 2 has the following problems. FIG.
In the optical modulator of the above, since each component in the TOAD 5 is connected by each fiber, the optical pulse trains S5 and S6 may become unstable. For example, the polarization planes of the traveling lights CW and CCW rotate due to the influence of vibration of each fiber due to an external force, expansion and contraction of each fiber due to a temperature change, and the interference between the traveling light CW and the traveling light CCW becomes unstable. Therefore, there is a problem that the intensity of the optical pulse trains S5 and S6 fluctuates with time. As a method of solving this, there is a method in which each fiber is composed of a polarization-maintaining optical fiber. In this case, in the optical coupler 5c that causes interference between the traveling lights CW and CCW, a branching ratio between the polarization plane and the light intensity is used. At the same time. In addition, in each connection portion of each component such as the optical coupler 5c and the optical delay unit 5k, the traveling light CW,
It is necessary to confirm the state of the polarization plane of CCW,
5 becomes complicated. Furthermore, since the polarization maintaining optical fiber is expensive, there is a problem that the price of the entire optical modulator increases.

[0007]

According to a first aspect of the present invention, there is provided an optical modulation apparatus comprising: a first optical pulse generator for generating a first optical pulse train having a repetition frequency of f;
A second light source that generates a second optical pulse train having the same phase as the first optical pulse train and a repetition frequency f / N (where N is an integer), and the same phase as the first optical pulse train A pulse pattern generator that generates a pulse pattern having a repetition frequency of f / N, an optical modulator that modulates the second optical pulse train based on the pulse pattern to generate an encoded modulated optical pulse train, A transmission reflector that transmits the first light pulse train and outputs a first transmitted light, and reflects a given first interference light to output a first reflected light; Transmitting the inside as optical space parallel light, performing interference based on the level of each light pulse in the modulated light pulse train with the first transmitted light, and applying the first interference light to the transmission reflector. And a second signal complementary to the first interference light. A spatial interference system that outputs interference light, a first optical filter that generates only first output light by passing only a wavelength component of the first optical pulse train from the first reflected light, and a second optical filter that generates the first output light. A second optical filter that generates only a second output light by passing only the wavelength component of the first optical pulse train from the interference light.

The spatial interference system transmits the first transmitted light, generates a second transmitted light having the same phase as the first transmitted light, and reflects the given second reflected light. And the second
A third reflected light having a phase opposite to that of the reflected light is generated, and a third reflected light having the same phase as the second reflected light is transmitted through the second reflected light.
And transmits the first transmitted light to reflect the first transmitted light.
Generating a fourth reflected light having the opposite phase to the transmitted light, and reflecting the given fifth reflected light to generate a sixth reflected light having the same phase as the fifth reflected light; The fifth reflected light is transmitted to generate a fourth transmitted light having the same phase as the fifth reflected light, and the third reflected light and the fourth transmitted light interfere with each other to produce the first reflected light. And a first transmission / reflection means for generating the second interference light by causing the sixth reflected light and the third transmitted light to interfere with each other.

Further, the spatial interference system reflects the second transmitted light to generate a seventh reflected light having a phase opposite to that of the second transmitted light, and provides a given eighth reflected light. First reflecting means for reflecting the reflected light to generate the fifth reflected light having a phase opposite to that of the eighth reflected light; and reflecting the seventh reflected light to form the seventh reflected light. Generates a ninth reflected light having a phase opposite to that of the first, and reflects the given first phase adjustment light to generate the first reflected light.
A second reflecting means for generating the eighth reflected light having the opposite phase to the phase adjusting light, and transmitting the modulated light pulse train;
The second reflected light is reflected to generate the second reflected light having the same phase as the second reflected light, and the fourth reflected light is reflected to reflect the fourth reflected light. A second transmitting / reflecting means for generating a tenth reflected light having the same phase as the light, and the tenth reflected light based on the level of each light pulse in the modulated light pulse train transmitted from the second transmitting / reflecting means. Phase adjustment means for performing phase adjustment on reflected light to generate the first phase adjustment light, and performing phase adjustment on the ninth reflected light to generate the second phase adjustment light; Are provided.

In the second invention, the phase adjustment means of the first invention is a non-linear medium for performing phase adjustment on the ninth and tenth reflected lights based on the level of each light pulse in the modulated light pulse train. Make up. According to the first and second aspects of the present invention, since the optical modulator is configured as described above, the first light source generates the first optical pulse train, and the second light source generates the second optical pulse train.
Is generated. Further, a pulse pattern is generated from the pulse pattern generator. The second optical pulse train is modulated by an optical modulator based on the pulse pattern, and an encoded modulated light pulse train is generated. The first
Is transmitted through the transmission reflector and output as the first transmitted light.

The first transmitted light is transmitted by the first transmitting / reflecting means as optical space parallel light, and a second transmitted light having the same phase as the first transmitted light is generated. The second transmitted light is reflected by the first reflection means, and a seventh reflected light having a phase opposite to that of the second transmitted light is generated. The seventh reflected light is reflected by the second reflecting means, and ninth reflected light having a phase opposite to that of the seventh reflected light is generated. The modulated light pulse train is transmitted by the second transmission / reflection means and provided to the phase adjustment means. The ninth reflected light is phase-adjusted by phase adjusting means based on the level of each light pulse in the modulated light pulse train, and is generated as second phase-adjusted light. The second phase adjusting light is reflected by the second transmitting / reflecting means, and a second reflected light having the same phase as the second phase adjusting light is generated. The second reflected light is reflected by the first transmitting and reflecting means, and a third reflected light having a phase opposite to that of the second reflected light is generated. Further, the second reflected light is transmitted by the first transmitting and reflecting means, and third transmitted light having the same phase as the second reflected light is generated.

On the other hand, the first transmitted light is reflected by the first transmitting / reflecting means, and a fourth reflected light having a phase opposite to that of the first transmitted light is generated. The fourth reflected light is reflected by the second transmission / reflection means, and a tenth reflected light having the same phase as the fourth reflected light is generated. The tenth reflected light is phase-adjusted by the phase adjusting means based on the level of each light pulse in the modulated light pulse train, and is generated as first phase-adjusted light. The first phase-adjusting light is the second phase-adjusting light.
, And an eighth reflected light having a phase opposite to that of the first phase adjusting light is generated. The eighth reflected light is reflected by the first reflecting means, and a fifth reflected light having a phase opposite to that of the eighth reflected light is generated. The fifth reflected light is reflected by the first transmitting / reflecting means, and a sixth reflected light having the same phase as the fifth reflected light is generated. The fifth reflected light is transmitted by the first transmitting / reflecting means, and a fourth transmitted light having the same phase as the fifth reflected light is generated. Then, in the first transmitting / reflecting means, the third reflected light and the fourth transmitted light interfere with each other to generate first interference light, and the sixth reflected light and the third The second interference light is generated by interference with the transmitted light. The first interference light is reflected by the transmission reflector and output as first reflected light. The first reflected light passes only the wavelength component of the first optical pulse train through the first optical filter, and the first output light is output. The second interference light passes only the wavelength component of the first optical pulse train through the second optical filter, and the second interference light passes through the second optical filter.
Is output. Therefore, the above problem can be solved.

[0013]

FIG. 1 is a block diagram of an optical modulation device showing an embodiment of the present invention. This optical modulation device is composed of, for example, a mode-locked semiconductor laser and a drive power supply for the same, as in the conventional FIG. 2, and generates a first light pulse train S1 having a repetition frequency f (for example, an ultra-high-speed A pulse light source 1 and a pulse laser such as a mode-locked semiconductor laser or a gain-switched semiconductor laser and a drive power supply for the laser. The pulse laser has the same phase as the optical pulse train S1 and a repetition frequency f / N (where N is an integer). A second light source (for example, a control pulse light source) 2 for generating an optical pulse train S2, a pulse pattern generator 3 for generating a pulse pattern S3 having the same phase as the optical pulse train S1 and a repetition frequency f / N, and an optical pulse train. S2 is modulated based on the pulse pattern S3,
And an optical modulator 4 for generating an encoded modulated optical pulse train S4. The control pulse light source 2 and the pulse pattern generator 3 are supplied with a synchronization signal sync from the ultrafast pulse light source 1 so that the light pulse train S1, the light pulse train S2, and the pulse pattern S3 have the same phase. It has become.

The optical modulation device includes an optical pulse train S1.
Transmitted through the first output a transmitted light th _1, a first interference light an if ₁ first transmission reflector for outputting reflected light re ₁ reflects the given and (e.g., a beam splitter) 7
And the transmitted light th ₁ transmits inside as light parallel light,
Perform interference based on the level of each optical pulse in the modulated optical pulse train S4 with respect to the transmitted light th _1, and outputs an interference light an if ₁ wherein the first given to the transmissive reflector 7, the interference light an if ₁ a first optical filter for generating a spatial interference system 10 for outputting a complementary second interference light an if _2, the first output light S21 is passed through only the wavelength component of the optical pulse sequence S1 from the reflected light re ₁ and 21, the second output light S2 and the second interference light an if ₂ passes only the wavelength component of the optical pulse sequence S1
And a second optical filter 22 for generating the second optical filter 2.

The spatial interference system 10 has first transmission / reflection means (for example, a beam splitter) 11. Beam splitter 11 is transmitted through the transmitted light th ₁ generates a second transmitted light th ₂ of the transmitted light th ₁ and the same phase, and reflects the second reflected light re ₂ given reflected light generating a third reflected light re _third opposite phase to re _2, generates a reflected light re ₂ and the third transmitted light th ₃ identical phase passes through the reflected light re _2, the transmission reflecting light th ₁ and generates a fourth reflected light th ₄ of opposite phase relative to the transmitted light th _1. Further, the beam splitter 11 reflects the reflected light re ₅ fifth given to produce reflected light re ₆ of the sixth reflected light re ₅ the same phase, the reflected light re
₅ to generate a _fourth transmitted light th ₄ having the same phase as the reflected light re ₅ , and the reflected light re ₃ and the transmitted light th ₄
DOO generates the interference light an if ₁ the first by interference, and generates a reflected light re ₆ and the interference light an if ₂ of the second interfere with each other the transmitted light th _3. Transmitted light t
h ₂ is a first reflection means (for example, a total reflection mirror) 12
To be incident on.

The total reflection mirror 12 reflects the transmitted light th ₂ and the seventh reflected light re having an opposite phase to the transmitted light th ₂ .
₇ generates the reflected light re ₅ of opposite phase to the reflected light re ₈ reflects the reflected light re ₈ eighth given and
Is generated. The reflected light re ₇ is incident on a second reflecting means (for example, a total reflection mirror) 13. The total reflection mirror 13, the reflected light re ₇ ninth reflected light re ₉ of opposite phase to the reflected light re ₇ reflects the
And reflects the given first phase adjustment light ph ₁ to generate the reflected light re ₈ having a phase opposite to that of the phase adjustment light ph ₁ .

The spatial interference system 10 has a second transmission / reflection means (for example, a beam splitter) 14. The beam splitter 14 transmits the modulated light pulse train S4,
Given second reflects the phase adjustment light ph ₂ to generate the reflected light re ₂ of the phase adjustment light ph ₂ and the same phase, the reflected light re ₄ and reflects the reflected light re ₄ The tenth reflected light re ₁₀ having the same phase is generated. The reflected lights re ₉ and re ₁₀ are incident on a phase adjusting means (for example, a nonlinear medium) 15. Nonlinear medium 1
5, for example, a semiconductor optical amplifier or the like, based on the level of each optical pulse in the modulated optical pulse train S4, which is transmitted from the beam splitter 14, the performing a phase adjustment to the reflected light re ₁₀ phase adjustment light ph ₁ and adjust the phase of the reflected light re ₉ to obtain the phase-adjusted light p.
It is intended to generate a h _2.

Next, the operation of FIG. 1 will be described. Repetition frequency f / NHz generated by the control pulse light source 2 (N is an integer)
Is input to the optical modulator 4, and the optical modulator 4 outputs a pulse pattern S4 encoded at f / N (bits / sec). The pulse pattern S4 is shaped into spatially parallel light via a collimator lens or the like (not shown) and input to the beam splitter 14 in the spatial interference system 10. On the other hand, an optical pulse train S1 having a repetition frequency of fHz output from the ultrafast pulse light source 1 is shaped into spatially parallel light via a collimator lens or the like (not shown) and transmitted through the beam splitter 7. The transmitted light th _{1 that} has been transmitted is
The light is incident on a beam splitter 11 in the spatial interference system 10. Transmitted light th incident on the beam splitter 11
₁ is branched into two systems of a transmitted light th ₂ and a reflected light re _4, and as spatial parallel light, the spatial interference system 10
After traveling through the inside, the beam returns to the beam splitter 11 and is transmitted and reflected.

That is, the transmitted light th ₁ is transmitted to the beam splitter 1
It is transmitted in 1, transmitted light th of the transmitted light th ₁ and the same phase
₂ is generated. Transmitted light th ₂ is reflected by the total reflection mirror 12, the reflected light re ₇ in opposite phase relative to the transmitted light th ₂
Is generated. The reflected light re ₇ is reflected by the total reflection mirror 13, the reflected light re ₉ antiphase is generated for the reflected light re _7. The modulated light pulse train S <b> 1 is transmitted through the beam splitter 14 and provided to the nonlinear medium 15. The reflected light re ₉ is phase-adjusted by the nonlinear medium 15 based on the level of each light pulse in the modulated light pulse train S 1 and is generated as phase-adjusted light ph ₂ . Phase adjustment light ph ₂ is reflected by the beam splitter 14, the reflected light re ₂ of the phase adjustment light ph ₂ and the same phase are generated. Reflected light re ₂ is reflected by the beam splitter 11, the reflected light re ₃ antiphase is generated for the reflected light re _2. The reflected light re ₂ is transmitted by the beam splitter 11, and a transmitted light th ₃ having the same phase as the reflected light re ₂ is generated.

On the other hand, the transmitted light th ₁ is transmitted to the beam splitter 1
Is reflected by 1, the reflected light re ₄ of opposite phase relative to the transmitted light th ₁ is generated. The reflected light re ₄ is reflected by the beam splitter 14, and the reflected light r having the same phase as the reflected light re ₄
e ₁₀ is generated. The reflected light re ₁₀ is a modulated light pulse train S
Based on the level of each light pulse in 4, the phase is adjusted by the nonlinear medium 15 and generated as phase adjusted light ph ₁ . Phase adjustment light ph ₁ is reflected by the total reflection mirror 13, the reflected light re ₈ antiphase is generated for the phase adjustment light ph _1. The reflected light re ₈ is reflected by the total reflection mirror 12, and a reflected light re ₅ having a phase opposite to that of the reflected light re ₈ is generated. The reflected light re ₅ is reflected by the beam splitter 11,
It reflected light re ₅ and reflected light re ₆ of the same phase are generated. Further, the reflected light re ₅ is transmitted by the beam splitter 11, transmitted light th ₄ of reflected light re ₅ and the same phase are generated.

[0021] Here, if there is no optical pulse train S4, the light passing through the nonlinear medium 15, the phase does not change, it becomes the same phase and the reflected light re ₃ and transmitted light th _4, the interference light there reinforce each other if ₁ is generated. Also, reflected light re
₆ and is reversed phase with transmitted light th _3, since mutually cancel each other, the interference light an if ₂ is not generated.

On the other hand, when there is an optical pulse train S4, an optical pulse train having a level such that the reflected light re ₃ and the transmitted light th ₄ have opposite phases and the reflected light re ₆ and the transmitted light th ₃ have the same phase. When S4 is input to the nonlinear medium 15, the reflected light re ₃ and the transmitted light th ₄ cancel each other, so that
Interference light an if ₁ is not generated. The reflected light re ₆ and the transmitted light th ₃ reinforce each other to generate interference light if ₂ . That is, the optical pulse train S1 input to the spatial interference system 10 is switched by the optical pulse train S4, and the switching cycle is N / f (sec). The gate time T of this switching window is: T = (the midpoint of the optical path of the spatial interference system 10 and the nonlinear medium 1
5), which is expressed by the optical distance between the position c and the speed c of the non-linear medium 15 and is not limited by the relaxation time of the nonlinear medium 15 (that is, the recovery time of the gain of the semiconductor optical amplifier).
The duty ratio of the interference lights if ₁ and if ₂ can be reduced.
The optical pulse train S1 input to the spatial interference system 10, since in the spatial interference system 10 is an optical space parallel light, the polarization plane of the light is always kept stable interference light an if _1, an if ₂ is obtained Can be Interference light an if ₁ is reflected by the beam splitter 7, reflected light re ₁ is generated. Since the reflected light re ₁ includes the optical pulse train S4, only the frequency component of the optical pulse train S1 passes through the optical filter 21, and the output light S21 is generated. Similarly, since the interference light an if ₂ includes an optical pulse train S4, the optical pulse sequence S1 through the optical filter 22
Only the frequency component of the light passes through, and the output light S22 is generated. FIG. 3 is a time chart showing the relationship between the output light S21 and S22 of FIG. 1, the gate time T of the switching window of the spatial interference system 10, and the light pulse train S1, in which the vertical axis represents light intensity and the horizontal axis represents time. t has been taken.

In FIG. 3, among the optical pulse trains S1 input to the spatial interference system 10, the pulses a and d entering the switching window have a bit rate f / N (bits / sec) in the output light S21 (this embodiment). In the embodiment, N = 3) encoding is performed with negative logic, and output light S22 is encoded using positive logic. Light pulses b and c that do not enter the switching window appear only in the output light S21. Thus, the spatial interference system 10
Is the optical pulse train S input from the beam splitter 11
To 1, when attention is focused on the interference light an if ₂ operates in the gate period N / f (sec), and the gate time T f /
N when acting as an AND gate encoded in (bits / sec), focused on the interference light an if _1, the same N
Acts as an AND gate. Further, if such a modulation method is applied N times to the output light S21, the light pulse a, d, light pulses b, e,... Are sequentially encoded into the light pulse train S1, and f (bits / sec) ) Is obtained.

As described above, in this embodiment, instead of the conventional fiber loop interference system, the spatial interference system 10 in which the optical spatial parallel light is transmitted is used. Not affected by expansion or contraction or vibration. Therefore, the polarization plane of the traveling light is always maintained, and the stable interference light i
f ₁ and if ₂ are obtained. Therefore, it is possible to generate the stable output lights S21 and S22 by encoding the ultrafast optical pulse train S1. Note that the present invention is not limited to the above embodiment, and various modifications are possible. For example, there are the following modifications. (A) The beam splitters 7, 11, and 14 may be other members as long as they transmit and reflect light, such as a half mirror. (B) The total reflection mirrors 12 and 13 may be other mirrors as long as they totally reflect light.

[0025]

As described above in detail, according to the first and second aspects of the present invention, instead of the conventional fiber loop interference system, a spatial interference system in which optical spatial parallel light is transmitted is used. Therefore, it is not affected by expansion and contraction or vibration of the fiber as in the related art. Therefore, the plane of polarization of the traveling light is always maintained, and stable first and second interference lights are obtained. Therefore, it is possible to encode the first optical pulse train and generate stable first and second output lights.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a light modulation device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a conventional light modulation device.

FIG. 3 is a time chart of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultra-high-speed pulse light source 2 Control pulse light source 3 Pulse pattern generator 4 Optical modulator 7, 11, 14 Beam splitter 10 Spatial interference system 12, 13, Total reflection mirror 15 Nonlinear medium 21, 22, Optical filter

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hiroshi Ogawa 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd.

Claims (2)

[Claims] 1. A first light source for generating a first optical pulse train having a repetition frequency f, and a second light having a repetition frequency f / N (N is an integer) having the same phase as the first optical pulse train. A second light source for generating a pulse train; and a repetition frequency f / N having the same phase as the first light pulse train.
A pulse pattern generator that generates a pulse pattern of: an optical modulator that modulates the second optical pulse train based on the pulse pattern to generate an encoded modulated optical pulse train; and transmits the first optical pulse train. A transmission reflector for outputting a first transmitted light and reflecting a given first interference light to output a first reflected light; wherein the first transmitted light is internally parallel as an optical space. To transmit
Interfering with the first transmitted light based on the level of each light pulse in the modulated light pulse train, outputting the first interference light to be provided to the transmission reflector, and outputting the first interference light A spatial interference system that outputs a second interference light complementary to the first light, and a first light that generates only a first output light by passing only a wavelength component of the first optical pulse train from the first reflected light. An optical modulator, comprising: a filter; and a second optical filter that generates only a second output light by passing only a wavelength component of the first optical pulse train from the second interference light. The interference system transmits the first transmitted light to generate second transmitted light having the same phase as the first transmitted light, and reflects the given second reflected light to generate the second reflected light. A third reflected light having a phase opposite to that of the light is generated, the second reflected light is transmitted, and the third reflected light is in the same position as the second reflected light. A third transmitted light of a phase is generated, the first transmitted light is reflected to generate a fourth reflected light having a phase opposite to the first transmitted light, and a given fifth reflected light is provided. Is reflected to generate a sixth reflected light having the same phase as the fifth reflected light, and is transmitted through the fifth reflected light to generate a fourth transmitted light having the same phase as the fifth reflected light. And causing the third reflected light and the fourth transmitted light to interfere with each other to generate the first interference light, and causing the sixth reflected light and the third transmitted light to interfere with each other. A first transmission / reflection means for generating the second interference light; and a means for reflecting the second transmission light to generate and provide a seventh reflection light having a phase opposite to that of the second transmission light. A first reflecting means for reflecting the obtained eighth reflected light to generate the fifth reflected light having a phase opposite to that of the eighth reflected light, and reflecting the seventh reflected light to produce the fifth reflected light. For the seventh reflected light A second generating a ninth reflected light having an opposite phase and reflecting the given first phase adjusting light to generate the eighth reflected light having a phase opposite to that of the first phase adjusting light; Reflecting means for transmitting the modulated light pulse train, reflecting the given second phase adjusting light to generate the second reflected light having the same phase as the second phase adjusting light, and A second transmitting / reflecting means for reflecting the fourth reflected light to generate a tenth reflected light having the same phase as the fourth reflected light; and the modulated light pulse train transmitted from the second transmitting / reflecting means. Based on the level of each light pulse, phase adjustment is performed on the tenth reflection light to generate the first phase adjustment light, and phase adjustment is performed on the ninth reflection light, Phase adjusting means for generating the second phase adjusting light;
An optical modulation device, comprising: 2. The method according to claim 1, wherein the phase adjusting unit is configured to control the ninth and first pulses based on a level of each light pulse in the modulated light pulse train.
2. The light modulation device according to claim 1, wherein the light modulation device is configured by a nonlinear medium that performs phase adjustment on the reflected light of zero.