JPH05121842A - Injection lock synchronization controller - Google Patents

Abstract

PURPOSE:To elevate the time stability without using oscillation delay time in the synchronization detection using real laser pulse by judging the synchronization state based on the magnitude of the amplitude of the wave by beat in respect of a feedback mechanism. CONSTITUTION:The peak of the temporal wave of a laser is made a, and the width from the peak to the minimum point appearing first is made b. A wave measuring instrument 21 measures a reflected beam, and outputs a wave signal to a digitizer 22. The digitizer 22 converts the wave signal into a digital signal, and sends the digital signal to a computer 23. The computer 23 seeks b/a which shows the amplitude of the beat wave based on this digital signal. Furthermore, the computer 23 sends the control signal, which changes the optical length of a laser oscillator so that this b/a may be minimum, to a piezocontroller 24. The piezocontroller 24 drives a piezoelement 25 according to the given control signal, and changes the optical length of the laser oscillator. This way, it keeps the synchronization state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tuning control device for a laser resonator using an injection lock method.

[0002]

2. Description of the Related Art Generally, a pulse-pumped laser oscillator simultaneously oscillates at a plurality of resonance frequencies determined by the optical length of a laser resonator. Therefore, several methods have been carried out to oscillate this at a single frequency, and one of them is a laser resonator using an injection lock method.

A laser resonator using the injection lock method is a combination of a parent laser (hereinafter, referred to as a master laser) and a child laser (hereinafter, referred to as a slave laser) resonator, which is formed from a master laser. A laser beam that is a weak seed of the laser beam is sent to the slave laser resonator, and a strong laser beam of the same quality as the master laser beam is obtained by using the gain of the strong laser excitation region of the slave laser resonator.

FIG. 4 shows an example of a conventional laser resonator using the injection lock method.
That is, the master laser 1 oscillated at a single frequency in advance
Is adjusted to the required intensity by the attenuator 2 and is injected into the gain 5 of the slave laser resonator through the folding mirror 3 and the injection mirror 4. Using this injected master laser light as a seed, it is possible to grow oscillation of a pulse laser and obtain strong laser light of the same quality as the master laser light.

As described above, the laser resonator using the injection lock method can oscillate the laser at a frequency determined by the frequency of the master laser. At this time, the oscillation frequency of the master laser and the resonance frequency determined by the optical length of the slave laser resonator must match (tune).

Therefore, it is necessary to provide an injection lock tuning control device in the laser resonator using the injection lock method. The injection lock tuning controller includes a detector 8 for detecting the tuning state of the laser resonator, a feedback mechanism 9 for controlling the optical length of the laser resonator based on the detected polarization direction signal, An adjusting mechanism 10 for adjusting the optical length of the laser resonator according to the feedback signal is provided, and the oscillation frequency of the master laser and the resonant frequency of the slave laser resonator are tuned.

[0007]

By the way, as a method of detecting the tuning state in the detector 8, the intensity of the master laser output from the output mirror 6 of the slave laser resonator is measured by a power meter to determine the resonance state. A method of investigating and a method of utilizing the fact that the time from the pulse excitation to the start of oscillation is minimized during tuning are used.

However, the injection lock tuning controller using the above detection method has the following problems to be solved. That is, the former has a problem that it does not necessarily match the tuning state in the oscillating state because the tuning detection is performed during non-oscillation. The latter is
Since it is necessary to use the oscillation delay time for the tuning, there is a drawback that the oscillation delay time becomes large at every constant period during control and the variation (jitter) of the oscillation delay time becomes large.

The present invention has been proposed in order to solve the above-mentioned drawbacks of the prior art, and its object is to perform synchronous detection using an actual laser pulse and without using an oscillation delay time. It is to realize an injection lock tuning control device with high time stability.

[0010]

SUMMARY OF THE INVENTION The present invention is a tuning control device arranged in a laser resonator using an injection lock method, and a waveform measuring device for measuring the output waveform of the laser, Injection mechanism including a feedback mechanism for determining a tuning state based on the generated waveform and transmitting a signal for controlling the optical length of the laser resonator, and an adjusting mechanism for adjusting the optical length of the laser resonator by the control signal In the lock tuning control device, the feedback mechanism determines the tuning state based on the magnitude of the amplitude of the waveform due to the beat.

[0011]

The present invention having the above construction operates as follows. That is, when tuning the injection lock,
Since the laser resonator oscillates at a single resonance frequency, its oscillating laser waveform has a smooth waveform with no beat.
On the other hand, when the injection lock is detuned, the laser resonator simultaneously oscillates at a plurality of frequencies, so that the oscillation laser waveform becomes a beat waveform.

Therefore, in the injection lock tuning controller of the present invention, when the waveform measured by the waveform measuring device is a smooth waveform without a beat, the feedback mechanism determines that the injection lock is in the tuning state. However, if the waveform measured by the waveform measuring device is a beat waveform, the feedback mechanism determines that the injection lock is in the detuning state,
A control signal that minimizes the amplitude of the waveform due to the beat is sent to the adjusting mechanism. The adjusting mechanism receives this signal and adjusts the optical length of the laser resonator. As a result, the injection lock synchronization state can be maintained at all times.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the injection lock tuning controller of the present invention will be described with reference to FIG. The same members as those of the conventional type shown in FIG. 4 are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 1, a beam splitter 20 is provided on the back side of the output mirror 6. A waveform measuring instrument 21 is provided so that the reflected light from the beam splitter 20 is sent. As the waveform measuring device 21, there is a Joule meter or the like for detecting a component orthogonal to the polarization direction of the master laser, and the output waveform of the reflected light is measured. In addition, the waveform measuring instrument 21 has a digitizer 2
2 is connected, and a computer 23 is connected to this digitizer 22. The digitizer 22 and the computer 23 constitute a feedback mechanism that determines a tuning state and sends out a signal for controlling the optical length of the laser resonator.

Further, a piezo controller 24 is connected to the computer 23, and a piezo element 25 is connected to the piezo controller 24. The piezo element 25 is attached to the rear mirror 7. These piezo controllers 2
4 and the piezo element 25 constitute an adjustment mechanism for adjusting the optical length of the laser resonator.

The relationship between the difference between the frequency of the injected light and the resonance frequency of the resonator and the oscillation frequency of the slave laser will be described with reference to FIG. As shown on the left side of the figure, when the frequency of the injected light and the resonance frequency of the resonator substantially match (tuned state), the slave laser oscillates at the single resonance frequency of the nearest resonator. Therefore, the output waveform becomes a smooth waveform with no beat. On the other hand, as shown on the right side of the figure, when the frequency of the injected light and the resonant frequency of the resonator are deviated (detuned state), the slave laser oscillates simultaneously at two frequencies close to the frequency of the injected light. Therefore, the output waveform becomes a beat waveform.

If the peak of the time waveform of the laser is a and the width from the peak to the minimum point that appears first is b, the amplitude of the waveform due to the beat can be expressed by b / a. That is, b / a becomes 0 at the time of perfect tuning, and b / a becomes 1 when the two resonance frequencies are completely detuned and oscillate with the same intensity. Therefore, single frequency oscillation can be performed by adjusting the optical length of the laser resonator so that b / a is minimized.

The injection lock tuning controller of this embodiment is constructed so that the oscillation frequency of the master laser and the resonance frequency of the slave laser resonator are tuned, paying attention to the above points. It is as follows.

That is, when the beam splitter 20 reflects a part of the light extracted from the output mirror 6 to the waveform measuring instrument 21, the waveform measuring instrument 21 measures the reflected light and outputs a waveform signal to the digitizer 22. The digitizer 22 converts the waveform signal into a digital signal and converts the digital signal into the computer 2
Send to 3.

The computer 23 obtains the b / a indicating the amplitude of the beat waveform based on this digital signal. Further, the computer 23 sends a control signal for changing the optical length of the laser resonator to the piezo controller 24 so that this b / a becomes minimum. The piezo controller 24 drives the piezo element 25 in accordance with the applied control signal to change the optical length of the laser resonator. In this way, the injection lock can always be kept in sync.

As described above, according to the injection lock tuning controller of this embodiment, since the synchronous detection is performed by using the actual laser pulse, the tuning state always matches the tuning state in the oscillation state. Further, since it is not necessary to use the oscillation delay time for tuning, the jitter becomes small and the control with high time stability becomes possible.

The present invention is not limited to the above embodiment, but also includes the embodiment shown in FIG. In the embodiment shown in the drawings, the piezo controller 24 is used as the adjusting mechanism.
Further, a master laser oscillation frequency stabilizing device 31 is provided in place of the piezo element 25, and tuning control is performed by controlling the oscillation frequency of the master laser. That is, similarly to the embodiment shown in FIG. 1, the computer 23 based on the output waveform measured by the waveform measuring device 21 outputs a control signal for minimizing b / a indicating the amplitude of the beat waveform of the master laser. It is sent to the oscillation frequency stabilizing device 31. As a result, the oscillation frequency stabilizing device 31 changes the oscillation wave number of the master laser. With such an embodiment, the same effect as that of the above embodiment can be obtained.

[0023]

As described above, according to the present invention, the feedback mechanism is the tuning control using the real laser light for judging the tuning state based on the magnitude of the amplitude of the waveform due to the beat and the oscillation. Since delay time is not used, in principle, tuning control with high time stability could be performed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of an injection lock tuning control device according to the present invention.

FIG. 2 is a principle diagram of an injection lock.

FIG. 3 is a configuration diagram of another embodiment of the injection lock tuning controller according to the present invention.

FIG. 4 is a configuration diagram of a conventional injection lock tuning control device.

[Explanation of symbols]

 1 Master Laser 2 Attenuator 3 Folding Mirror 4 Injection Mirror 5 Gain 6 Output Mirror 7 Rear Mirror 20 Beam Splitter 21 Waveform Measuring Instrument 22 Digitizer 23 Calculator 24 Piezo Controller 25 Piezo Element 31 Oscillation Frequency Stabilizer a Laser Waveform Peak b Width from peak to first appearing minimum point b / a Waveform amplitude due to beat

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[Procedure amendment]

[Submission date] December 11, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

Therefore, it is necessary to provide an injection lock tuning control device in the laser resonator using the injection lock method. This injection lock tuning controller includes a detector 8 for detecting the tuning state of the laser resonator, and a feedback mechanism 9 for controlling the optical length of the laser resonator based on the detected signal.
And an adjusting mechanism 10 for adjusting the optical length of the laser resonator according to the feedback signal, and are configured so that the oscillation frequency of the master laser and the resonance frequency of the slave laser resonator are tuned.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

As shown in FIG. 1, a beam splitter 20 is provided on the back side of the output mirror 6. A waveform measuring instrument 21 is provided so that the reflected light from the beam splitter 20 is sent. As the waveform measuring device 21, photoelectric
There are tubes, photon drags, etc., and the output waveform of the reflected light is measured. A digitizer 22 is connected to the waveform measuring instrument 21, and a computer 23 is connected to the digitizer 22. The digitizer 22 and the computer 23 constitute a feedback mechanism that determines a tuning state and sends out a signal for controlling the optical length of the laser resonator.

Claims (1)

[Claims] 1. A tuning control device arranged in a laser resonator using an injection lock method, wherein a waveform measuring device for measuring an output waveform of the laser and a tuning state are judged by the measured waveform. A feedback mechanism for sending a signal for controlling the optical length of the laser cavity, and an adjusting mechanism for adjusting the optical length of the laser cavity by the control signal An injection lock tuning control device characterized in that the mechanism judges the tuning state based on the magnitude of the amplitude of the waveform due to the beat.