JP2003043528A - 4-wave mixer using ring laser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a 4-wave mixer using a ring laser which has a constitution simpler than conventional one and can easily change a wavelength for use though a conventional mixer requires signal light and exciting light and admits of simplification and has restrictions on applicable frequencies. SOLUTION: The 4-wave mixer is provided with a first optical coupler, a gain medium, a second optical coupler, an optical path connecting a second output end of the second optical coupler and a second input end of the first optical coupler, a first optical filter arranged on an optical path connecting a first output end of the second optical coupler and the second input end of the first optical coupler, an optical delay device, a constitution for inputting an optical signal to a first input end of the first optical coupler, and a constitution for sending the optical signal from the first output end of the second optical coupler.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device utilizing the four-wave mixing phenomenon in a gain medium that occurs in a mode-locked laser having a ring structure, and more particularly to an optical division demultiplexer, an optical sampling device, or an optical wavelength converter. And a four-wave mixing device using a ring laser.

[0002]

2. Description of the Related Art There are already known some devices utilizing the four-wave mixing phenomenon that occurs when light from a plurality of light sources is passed through an optical medium exhibiting a non-linear response.

For example, reference 1 (S. Kawawanishi, T. Moriok
a, O.Kamatani, H.Takara, JMJacob, and M.Saruwatar
i, “100Gbit / s all-optical demultiplexing using four
-wavemixing in a traveling wave laser diode amplif
ier ”, Electron.Lett., vol.30, no.12, pp.981-982,
Jun. 9, 1994., (S. Kawanishi, T. Morioka, O. Kamatani, H. Takara, JM Jacob, M. Saruwatari, "Using a four-wave mixing like traveling-wave laser diode amplifier 10
0 Gbit / s all-optical demultiplexing ", Electron.Le
tt., Vol. 30, No. 12, pp. 981-982, June 9, 1994)), as shown in FIG. 7 (a), two types of light, that is, the input light and the light from the clock light generator are used. A demultiplexing device that demultiplexes the demultiplexed optical signal by performing four-wave mixing by simultaneously passing the light from the light source through one element demultiplexing (DEMUX) element traveling wave laser diode amplifier is described. Has been done. In this device, one of the two light sources is a modulated optical signal and the other is an optical pulse from a mode-locked EDF (erbium-doped fiber laser).

In the apparatus shown in FIG. 7A, the four-wave mixing light is output only when the clock light coincides with the input light shown in FIG. 7B as indicated by the dotted line. It is to perform demultiplexing.

In this multiplexer / demultiplexer, the multiplexer / demultiplexer (DE
The MUX) element performs the operation of extracting (switching) the signal light of the time-determined repetition (clock) from the demultiplexed demultiplexed (DEMUX) signal light (input). A clock light generator was needed. With this configuration, there was still room for simplification.

Further, Japanese Patent Laid-Open No. 9-33967 discloses that
A four-wave mixing light generation circuit capable of separating and extracting four-wave mixing light (wavelength conversion light, phase conjugate light) from signal light and pumping light without using wavelength separation means such as a wavelength filter, and the same are used. An optical circuit is disclosed. this is,
The third port of the 2 × 2 optical branching coupler and the optical nonlinear medium are connected by a dispersive medium having a predetermined length and a propagation constant, and the fourth port and the optical nonlinear medium have a predetermined length and a propagation constant. The signal light S (carrier angular frequency ω _S ) and the pumping lights P1, P2 (carrier angular frequency ω _P1 ,
ω _P2 ) is input from the first port of the optical branching coupler, and the four-wave mixed light (carrier angular frequency ω _f = ω _P1 + ω _P2 − ω _S ) generated from the optical nonlinear medium is extracted from the second port. .

The optical circuit disclosed here requires signal light and pumping light as in the above-described device, and an independent generator is used to generate pumping light. There was room for simplification.

Reference 2 (Shin Arahira, Yukio Kato, Ogawa)
Yo, also using four-wave mixing in mode-locked DBR lasers
Wavelength Conversion Experiment ", 2001 Spring Bibliography Proceedings, 29a-ZV
-8, p. 1173, 2001.), as shown in FIG.
Fabry-Perot mode-locking of light from two light sources
Generated by this laser through a distributed feedback (DBR) laser
Describes a wavelength conversion device that performs four-wave mixing with the generated optical pulse
Has been done. In this device, signal light (wavelength = λ
s), four-wave mixing (FWM) light (wavelength =
λ _FWM) And mode-locked light (wavelength = λp) and signal light
(Wavelength = λs) is output.

This device is characterized in that it has fewer constituent parts than the device of the above-mentioned document 1. However, since it is a monolithic structure, it is an integrated type, so that it is difficult to control the resonator length, and it is difficult to adjust the separation frequency or the oscillation wavelength. If the oscillating wavelength cannot be changed, it may happen that the signal light that matches or is close to the oscillating wavelength cannot be separated.

[0010]

As described above, in the above-mentioned device utilizing the four-wave mixing phenomenon, the signal light and the pumping light are required, and the pumping light is generated in order to generate the pumping light. Due to the use of the light generator, this configuration still has room for simplification and limits the applicable frequencies.

The present invention has been proposed in view of the above,
An object of the present invention is to provide a four-wave mixing device using a ring laser which has a simpler structure than the conventional structure and whose wavelength to be used can be easily changed.

[0012]

In order to achieve the above object, the present invention provides a conventional laser oscillator and a non-linear element by performing four-wave mixing using the non-linear response characteristic of a gain medium in a laser resonator. The first invention in the present invention is a first optical coupler having at least a first input end, a second input end, and an output end, and It has a gain medium connected to the first optical coupler having a gain characteristic with respect to the laser light used by an optical path, and at least an input end, a first output end, and a second output end connected to the gain medium by an optical path. A second optical coupler and a second
Optical path connecting the second output end of the optical coupler and the second input end of the first optical coupler, and the first output end of the second optical coupler and the first optical coupler of the first optical coupler. A first optical filter arranged on an optical path connecting the second input end and an optical delay device; a configuration for inputting an optical signal to the first input end of the first optical coupler; The optical signal is transmitted from the first output end of the optical coupler.

Further, in the above structure, other light of the intended four-wave mixing light is also included. However, in order to select only the four-wave mixing light, the second invention in the present invention is at least the second invention. 1st with 1 input and 2nd input and output
Optical coupler, a gain medium connected to the first optical coupler having a gain characteristic with respect to the laser light to be used by an optical path, and at least an input end, a first output end, and a first output end connected to the gain medium by an optical path. A second optical coupler having two output terminals, an optical path connecting the second output terminal of the second optical coupler and the second input terminal of the first optical coupler, and the second optical path A first optical filter arranged on an optical path connecting a first output end of the optical coupler and a second input end of the first optical coupler, and an optical delay device, and a first optical coupler of the first optical coupler. A configuration for inputting an optical signal to the first input end;
The second optical filter is connected to the first output end of the optical coupler by the optical path, and the optical signal is transmitted from the second optical filter.

The third aspect of the present invention is the first aspect.
Alternatively, in the configuration of the second invention, in order to configure the mode-locked laser, the above-mentioned first or second
In addition to the configuration of the invention described above, an optical modulator is further arranged on the optical path connecting the first output end of the second optical coupler and the second input end of the first optical coupler. I am trying.

In addition, in a fourth aspect of the present invention, in order to configure an optical division demultiplexer, in addition to the configuration of the above-mentioned third aspect, a first input end, a second input end and an output are provided. A first optical coupler having an end, a gain medium connected to the first optical coupler having a gain characteristic with respect to the laser light to be used by an optical path, and at least an input end connected to the gain medium by an optical path. A second optical coupler having a first output end and a second output end, and an optical path connecting a second output end of the second optical coupler and a second input end of the first optical coupler. And a first optical filter, an optical delayer, and an optical modulator arranged on an optical path connecting the first output end of the second optical coupler and the second input end of the first optical coupler. And a first optical pulse signal input to the first input end of the first optical coupler, and An optical division demultiplexing device is configured by outputting a four-wave mixing light generated when the second optical pulse signal generated by the hard-locked laser is superposed on the gain medium. .

In addition, in a fifth aspect of the present invention, in order to configure an optical sampling device, in addition to the configuration of the third aspect described above, a first input end, a second input end and an output end are provided. A first optical coupler having the same, a gain medium connected to the first optical coupler having a gain characteristic with respect to the laser light used by an optical path, and at least an input end connected to the gain medium by an optical path and a first optical medium. A second optical coupler having an output end and a second output end, and an optical path connecting the second output end of the second optical coupler and the second input end of the first optical coupler, A first optical filter, an optical delay device, and an optical modulator arranged on an optical path connecting the first output end of the second optical coupler and the second input end of the first optical coupler; , A mode-locked laser is configured, and a configuration in which a repetitive signal is input to the first input end of the first optical coupler, The optical sampling device is configured by including a configuration for changing a modulation signal input to the container, a unit for converting the output optical signal into an electrical signal, and a unit for displaying the electrical signal. .

A sixth aspect of the present invention is, in addition to the configuration of the third aspect of the invention described above, to configure an optical frequency converter, a first input end, a second input end and an output end. A first optical coupler having a gain, a gain medium connected to the first optical coupler having a gain characteristic with respect to the laser light used by an optical path, and at least an input end connected to the gain medium by an optical path And an optical path connecting the second output end of the second optical coupler and the second input end of the first optical coupler. , A first optical filter, an optical delayer, and an optical modulator arranged on an optical path connecting the first output end of the second optical coupler and the second input end of the first optical coupler And form a mode-locked laser.
Structure for inputting a repetitive signal to the first input end of the optical coupler, means for generating a synchronizing signal synchronized with the repetitive signal input to the first input end, and the optical modulation of the synchronizing signal. The optical frequency conversion device is configured by including the configuration for inputting to the device.

The seventh aspect of the present invention is to satisfy the oscillation condition of the mode-locked laser so that the sixth aspect of the invention described above can be achieved.
In addition to the configuration of the invention described above, there is provided means for adjusting the optical path length of the resonator of the mode-locked laser by adjusting the optical delay device according to the information regarding the frequency of the repetitive signal input to the first input terminal. It is characterized by that.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. First, an optical division demultiplexing apparatus will be shown as a first embodiment, an optical sampling apparatus will be shown as a second embodiment, and an optical frequency conversion apparatus will be shown as a third embodiment. In addition, about the code | symbol attached | subjected to drawing, what has the same function or the same shape, and it is not necessary to distinguish with a different code | symbol, it demonstrates using the same code | symbol.

First, as a first embodiment, FIG. 1 shows a first embodiment which constitutes an optical division multiplexer / demultiplexer. Figure 1
The device is an optical coupler 1, an isolator 2, an oscillation wavelength =
1.55 μm band semiconductor optical amplifier 3, isolator 4,
An optical coupler 5, an optical filter 6 having a transmission wavelength of 1.55 μm and a bandwidth of 3 nm, a delay device 7, a polarization plane controller 8, a modulator 9,
Optical splitter 1 of a mode-locked laser device having a ring-shaped resonator composed of a polarization controller 10 and an optical path connecting them.
From the mode-locked laser section, the optical pulse signal is input from the optical multiplexer 5 to the outside of the mode-locked laser section, and separated by the optical filter 6 having a transmission wavelength of 1.54 μm and a bandwidth of 3 nm. Configured to obtain an optical signal.

The oscillation wavelength of the mode-locked laser device can be arbitrarily set by the optical filter 6 (transmission wavelength = λ _P ) inserted in the resonator. Since an optical filter capable of changing the transmission wavelength is already on the market, it can be used. As is well known, when a signal from a 10 GHz high frequency oscillator 20 is applied to the modulator 9, mode lock occurs and pulse oscillation occurs. Further, the modulator 9 may be an intensity modulator, a phase modulator, or a polarization modulator. Isolators 2, 4
Is an optical element capable of propagating light in one direction,
As a result, the ring structure is such that the light circulates in one direction. The modulator 9 is used to modulate the circulating light in accordance with an integral multiple of the circulating time, whereby mode locking occurs and an optical pulse is generated. Further, the circulation time of the optical pulse in the ring resonator is continuously variable by a time delay device (TimeDelay). Since a time delay device capable of changing the delay time is already on the market, this can be used. Polarization plane controller (PC) 8 and 1 inserted in the resonator
0 is used to match the polarization because the semiconductor optical amplifier 3 and the modulator 9 have polarization dependency. Similarly, it is desirable that the optical path is also composed of a polarization maintaining optical fiber.

For example, when a signal light of wavelength = 1.56 μm is input to this optical division demultiplexer, 10% of it is a mode-locked laser by the optical coupler 1 (input = 10%, ring resonator = 90%). Input to the device section. In the semiconductor optical amplifier of the mode-locked laser device, an optical signal passed through the optical coupler 1 is an optical pulse (wavelength λ _p = 1.55) in which the input signal light of wavelength λ _s = 1.56 μm circulates in the ring.
(4 μm), the four-wave mixing phenomenon occurs due to the nonlinearity of the gain medium, and a new optical signal is generated. This is the light (wavelength λ _d = 1.
54 μm) (DEMUX light).

The separated light is taken out of the resonator by the optical coupler 5 (ring resonator = 90%, output = 10%). However, the light extracted here includes the input optical signal (wavelength = λ _s ) and mode-locked pulse light (wavelength = λ _s ).
Since λ _p ) and the separated light (wavelength = λ _d ) are mixed, only the separated light (wavelength = λ _d ) is extracted using the optical filter 11 (transmission wavelength = λ _d ).

By such an operation, when the repetition frequency of the light pulse of the mode-locked laser device is f (Hz), only the input pulse that coincides with the light pulse is separated, so that a plurality of pulses having the same repetition frequency are obtained. It is obvious that any pulse train can be separated from a signal in which the pulse trains are mixed at appropriate intervals.

As a second embodiment of the optical division demultiplexer, an embodiment of the optical division demultiplexer using a half fiber amplifier is shown in FIG. The apparatus shown in FIG. 2 is the same as the semiconductor optical amplifier 3 in the first embodiment, except that the fiber amplifier 1
It is replaced by 5. This fiber amplifier 15
Is composed of an erbium-doped optical fiber 12, a laser diode 14 having an oscillation wavelength of 1480 nm and an output of 200 nW, and a two-wavelength multiplex demultiplexer 13 as its pumping light source. In this 2-wavelength multiplex demultiplexer 13, 1.55
The light of μm is transmitted as it is, and the light of 1.48 μm is coupled. Here, by inputting the pumping light so as to propagate in the direction opposite to the direction of the input optical signal, interference by the pumping light can be avoided. The features of this device are:
Compared with the optical division demultiplexer according to the first embodiment described above, a short optical pulse can be generated, and there is an effect that time resolution can be increased in performing optical sampling and the like.

Next, as a second embodiment, FIG. 3 shows a third embodiment configured as an optical sampling device.
This is for observing the pulse waveform of the pulse light source. The optical signal from the pulse light source 20 is input to the sampling unit 17 having the same configuration as in FIG. Here, it is assumed that the pulse light source 20 is performing pulse oscillation according to a high frequency signal from the high frequency oscillator 21 (oscillation frequency = 10 GHz). This high frequency signal is periodically phase-shifted at a lower frequency (frequency = 100 Hz) of the phase shifter 22 according to the electric signal from the sawtooth oscillator 23.
The phase-shifted high frequency signal is supplied to the optical modulator 9 of the sampling unit. The repetition frequency of the pulse oscillation of the mode-locked laser formed in the sampling unit 17 slightly fluctuates around the original high frequency signal, so that the oscillation pulse of the mode-locked laser fluctuates slightly with time. become. The four-wave mixed light of the pulse that slightly fluctuates with time and the pulsed light from the pulsed light source is detected by the photodetector (P
D) is converted to an electric signal by 3, filtered by a low-pass filter, amplified by an amplifier to a sufficient voltage, and observed by an oscilloscope 24. At that time, the voltage of the sawtooth wave on the horizontal axis,
By observing the output of the photodetector on the vertical axis, the pulse waveform of the pulse light source can be obtained.

Next, a fourth embodiment constructed as an optical sampling device is shown in FIG. This is for observing the pulse waveform of the pulse light source. The optical signal from the pulsed light source 20 is branched by the optical coupler 30, and a part of the optical signal is converted into an electric signal by the photodetector 31 to be filtered by the filter 3
After being filtered by 2, the sync signal is generated by the sync oscillator 33. The method of generating this synchronization signal is well known,
For example, there is a phase locked loop (PLL) circuit. This synchronizing signal is phase-modulated and phase-shifted according to the electric signal from the sawtooth oscillator 23. This phase shifted high frequency signal is
It is supplied to the optical modulator 9 of the sampling unit 17. As a result, the repetition frequency of the pulse oscillation of the mode-locked laser of the sampling unit 17 fluctuates slightly around the original high frequency signal, so that the oscillation pulse of the mode-locked laser fluctuates slightly with time. Become. The four-wave mixed light of the pulse that slightly fluctuates with time and the pulsed light from the pulse light source is converted into an electric signal by the photodetector 3, and the sawtooth voltage is plotted on the horizontal axis to output the photodetector. The pulse waveform of the pulse light source can be obtained by observing with the oscilloscope 24 with the vertical axis.

Next, as a third embodiment, FIG. 5 shows a fifth embodiment configured as an optical frequency converter. This is a laser light source 1 which is a pulse light source or a continuous light source.
The light from 9 is input, four-wave mixed light with the laser light by the ring laser unit is generated, and the four-wave mixed light is selected and output by the optical filter 11 to convert the frequency of the input laser light. Is to do. Here, it is obvious that the input optical signal may be pulsed light or continuous light. Further, it is obvious that the laser light from the ring laser may be pulsed light or continuous light.

Next, a sixth embodiment constructed as an optical frequency converter is shown in FIG. This is for converting the frequency of the pulsed light. The optical signal from the pulse light source 20 is branched by the optical coupler 30, a part of which is converted into an electric signal by the photodetector 31, filtered by the filter 32, and then generated by the synchronous oscillator 33. It This synchronizing signal is amplified by the power amplifier 36 and then added to the modulator 9 for mode synchronization. Further, since the resonator length does not always match the mode-locking frequency as it is, the frequency of the signal from the output of the PLL circuit is detected by the frequency meter 34, and the delay device 7 is connected to the computer based on the detection result. It is controlled by the control device 35 used.

In this way, by making the input pulsed light and the pulsed light generated by the mode-locked laser positionally coincide with each other, it is possible to perform four-wave mixing between the pulsed lights having large peak powers. Therefore, frequency conversion of pulsed light can be efficiently performed.

[0031]

Since the present invention has the above-mentioned structure,
The effects described below can be achieved. First
In the present invention, the four-wave mixing is performed by using the nonlinear response characteristic of the gain medium in the ring laser resonator, so that the laser oscillator and the nonlinear element have been conventionally used, but this configuration is simplified. I was able to.

Further, in the second invention, only the desired optical signal is selected by the optical filter from the plurality of optical signals generated by the four-wave mixing light, so that the output optical signal can be used easily. .

Further, in the third aspect of the invention, the optical modulator is arranged in the laser resonator, so that it can be operated as a mode-locked laser.

Further, according to the fourth aspect of the present invention, by inputting an optical pulse while operating as a mode-locked laser, an optical division demultiplexer according to the oscillation pulse of the mode-locked laser can be constructed. .

According to the fifth aspect of the invention, while operating as a mode-locked laser, an optical pulse is input and the modulation frequency input to the optical modulator is changed, so that the oscillation pulse of the mode-locked laser is sampled. It became possible to configure the optical sampling device.

In the sixth or seventh aspect of the invention, an optical pulse is input while operating as a mode-locked laser, and a signal synchronized with the input pulse is input to the optical modulator, whereby the efficiency is improved. An optical frequency converter that can convert the frequency of an optical pulse can now be constructed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment constituting an optical division demultiplexer.

FIG. 2 is a block diagram showing a second embodiment which constitutes an optical division demultiplexer.

FIG. 3 is a block diagram showing a third embodiment of the optical sampling device.

FIG. 4 is a block diagram showing a fourth embodiment of the optical sampling device.

FIG. 5 is a block diagram showing a fifth embodiment of the optical frequency converter.

FIG. 6 is a block diagram showing a sixth embodiment constituting an optical frequency converter.

7A and 7B are diagrams showing a demultiplexing device that demultiplexes a split-multiplexed optical signal according to a conventional technique, FIG. 7A is a block diagram thereof, and FIG. 7B is a timing diagram showing a pulse operation. is there.

FIG. 8 is a diagram showing a wavelength conversion device that performs wavelength conversion of laser light according to a conventional technique, (a) is a block diagram thereof, and (b) is a spectrum arrangement diagram of output light.

[Explanation of symbols]

1 Optical coupler 2 Isolator 3 Semiconductor optical amplifier 4 Isolator 5 Optical coupler 6 Optical filter 7 delay device 8 Polarization controller 9 modulator 10 Polarization controller 11 Optical filter 12 Erbium-doped optical fiber 13 Two-Wavelength Multiplexer 17 Sampling unit 19 Laser light source 20 pulse light source 21 high frequency oscillator 22 Phase shifter 23 Two-Wavelength Multiplexer 24 Oscilloscope 25 amps 26 filters 30 Optical coupler 31 Photodetector 32 filters 33 Synchronous oscillator 34 Frequency meter 35 Control device 36 Power Amplifier

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Wataru Nakajo             4-2-1 Kanaikitamachi, Koganei City, Tokyo Independent             Communications Research Institute F term (reference) 2K002 AA02 AA04 AB12 BA02 BA03                       CA13 CA15 DA10 DA11 EA29                       EA30 HA31                 5F072 AB09 AB13 AK06 LL17 LL19                       MM03 MM07 PP07 QQ04 SS08                       YY11 YY15

Claims (7)

[Claims] 1. An optical path to a first optical coupler having at least a first input end, a second input end and one output end, and a first optical coupler having a gain characteristic with respect to a laser beam used. A gain medium connected to the gain medium, a second optical coupler having at least one input end, a first output end, and a second output end connected to the gain medium by an optical path; and a second optical coupler. Second
An optical path connecting the output end of the first optical coupler and the second input end of the first optical coupler, and the first output end of the second optical coupler and the second input end of the first optical coupler. A first optical filter and an optical delay unit arranged on an optical path connecting the optical path, a configuration for inputting an optical signal to a first input end of the first optical coupler, and a first optical coupler for the second optical coupler. A four-wave mixing apparatus using a ring laser, wherein the optical signal is transmitted from an output end. 2. A first optical coupler having at least a first input end, a second input end, and one output end, and a first optical coupler having a gain characteristic with respect to a laser beam used, in an optical path. A gain medium connected to the gain medium, a second optical coupler having at least one input end, a first output end, and a second output end connected to the gain medium by an optical path; and a second optical coupler. Second
An optical path connecting the output end of the first optical coupler and the second input end of the first optical coupler, and the first output end of the second optical coupler and the second input end of the first optical coupler. A first optical filter and an optical delay unit arranged on an optical path connecting the optical path, a configuration for inputting an optical signal to a first input end of the first optical coupler, and a first optical filter for the second optical coupler. A second optical path connected to the output end
A four-wave mixing device using a ring laser, comprising: an optical filter of 1) and a configuration in which an optical signal is transmitted from the second optical filter. 3. A four-wave mixing device using a ring laser according to claim 1, wherein the first output end of the second optical coupler and the second output end of the first optical coupler.
A four-wave mixing device using a ring laser, wherein an optical modulator is further arranged on the optical path connecting the input end of the. 4. A four-wave mixing device using a ring laser according to claim 3, wherein the first optical coupler has at least a first input end, a second input end and an output end, and a laser used. It has a gain medium connected to a first optical coupler having a gain characteristic for light by an optical path, and at least one input end, a first output end, and a second output end connected to the gain medium by an optical path. A second optical coupler, an optical path connecting the second output end of the second optical coupler and the second input end of the first optical coupler, and the first optical coupler of the second optical coupler. A first optical filter, an optical delay device, which is arranged on an optical path connecting the output end of the first optical coupler and the second input end of the first optical coupler.
A mode-locked laser is configured by the optical modulator and the optical modulator, and the first optical pulse signal input to the first input end of the first optical coupler and the second optical pulse generated by the mode-locked laser described above. A four-wave mixing device using a ring laser, characterized in that an optical division demultiplexing device is constructed by outputting four-wave mixing light generated when the signal and the gain medium are superposed on each other. 5. A four-wave mixing device using a ring laser according to claim 3, wherein the first optical coupler has at least a first input end, a second input end, and one output end, A gain medium connected by an optical path to a first optical coupler having a gain characteristic for the laser light used, and at least one input end, a first output end, and a second output end connected to the gain medium by an optical path. A second optical coupler having a second optical coupler, a second output end of the second optical coupler, and a first optical coupler.
Is arranged on the optical path connecting the second input end of the optical coupler and the optical path connecting the first output end of the second optical coupler and the second input end of the first optical coupler. A mode-locked laser is configured by the first optical filter, the optical delay device, and the optical modulator, and a configuration in which a repetitive signal is input to at least the first input end of the first optical coupler, and the above optical modulation An optical sampling device is configured by including a configuration for changing a modulation signal input to a container, a unit for converting an output optical signal into an electric signal, and a unit for displaying the electric signal. Four-wave mixer using a ring laser. 6. A four-wave mixing device using a ring laser according to claim 3, wherein the first optical coupler has at least a first input end, a second input end, and one output end, A gain medium connected by an optical path to a first optical coupler having a gain characteristic for the laser light used, and at least one input end, a first output end, and a second output end connected to the gain medium by an optical path. A second optical coupler having a second optical coupler, a second output end of the second optical coupler, and a first optical coupler.
Is arranged on the optical path connecting the second input end of the optical coupler and the optical path connecting the first output end of the second optical coupler and the second input end of the first optical coupler. A mode-locked laser is configured by the first optical filter, the optical delay device, and the optical modulator, and a configuration in which a repetitive signal is input to the first input end of the first optical coupler, and the first input A ring characterized in that an optical frequency conversion device is configured by including means for generating a synchronization signal synchronized with a repetitive signal input to an end, and a configuration for inputting the synchronization signal to the optical modulator. Four wave mixer using a laser. 7. The four-wave mixing device using the ring laser according to claim 6, further comprising: adjusting an optical delay device according to information about a frequency of a repetitive signal input to the first input end. A four-wave mixing device using a ring laser, comprising means for adjusting the optical path length of the resonator of the mode-locked laser.