JPH0399483A - Pulse laser device - Google Patents

Abstract

PURPOSE:To obtain output pulse laser rays always locked in a longitudinal mode by injection by a method wherein a part of the output pulse laser rays of a slave pulse laser device is monitored to synchronously control the pulse laser device. CONSTITUTION:A feedback loop composed of a detector 20, a computer 9, a piezoelectric driver 10, and a piezoelectric element 11 is built in a pulse laser device of this design. The oscillation starting time of the optical waveform or the energy waveform of the laser rays measured by the detector 20 is obtained by the computer 9, and the piezoelectric element 11 is made to start operating corresponding to the obtained result. A resonator is changed in length so as to make an oscillation delay time between a reference time and an oscillation starting time minimal. By this setup, slave laser rays locked by injection can be always oscillated.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is directed to injecting a weak pulsed laser beam from a driving side pulsed laser device to a driven side pulsed laser device. The present invention relates to a pulsed laser device with an injection lock configuration, which oscillates an intense pulsed laser beam having the same wavelength as the pulsed laser beam on the drive side from the device.

(Prior art) As this type of pulse laser device, for example, TE A
-C02 laser is present. This configuration is shown in FIG.

In FIG. 6, 1 is a pulse laser device on the driving side (hereinafter referred to as a master laser), and 2 is a master laser beam from the master laser 1. 3 to 6 are components of the driven side pulse laser device (hereinafter referred to as slave laser), 3 is a discharge section, and 4 is an output mirror.
5 is a rear mirror, and 6 is an injection mirror. A part of the master laser beam 2 output from the master laser 1 is reflected by the injection mirror 6 and guided into the resonator of the slave laser, whereby the slave laser generates a pulse with the same wavelength as the master laser beam 2. A condition is created in which it is easy to oscillate laser light. Master Laser 1. And the slave lasers (3 to 6) constitute an optical system of the injection lock.

7 is a beam splitter that reflects a part of the pulsed laser light output from the output mirror 4 and guides it to the monitoring detector 8.

The monitoring detector 8 has a function of continuously measuring the interference output on the output side or the transmission side using a power meter and sending the signal to the computer 9.

The computer 9 has a function of processing the signal sent from the detector 8 and sending the processing result to the piezo driver 10.

The piezo driver 10 has the function of amplifying the signal sent from the computer 9 and applying an appropriate voltage to the piezo element 11. The piezo element 11 changes its thickness according to the applied voltage, and the slave It has the function of adjusting the laser cavity length.

Reference numeral 12 indicates a pulsed slave laser beam output from the output mirror, and reference numeral 13 indicates an interference output on the output side.

Reference numeral 14 indicates a master laser beam transmitted through the injection mirror 6, and reference numeral 15 indicates an interference output on the transmission side.

In conventional pulsed laser devices, including the device shown in Fig. 6, control to maintain mode locking involves treating the slave laser resonator as an interferometer, moving the resonator length with a piezo element, etc., and controlling the injection light. Feedback control is performed using the interference output.

However, when using the interference light on the output side in this way, there is a drawback that the high output pulse of the slave laser is superimposed, and as the number of repetitions increases, it becomes difficult to judge the interference light. Furthermore, when using the interference light on the transmission side, there is a drawback that the master laser light that passes through the injection mirror is strong against the interference output, and contrast cannot be obtained.

As a result, feedback control becomes ineffective, and the longitudinal mode rotor becomes unstable as it either engages or disengages.

(Problems to be Solved by the Invention) As described below, in the conventional pulse laser device with an injection lock configuration, when the number of oscillation repetitions increases, the output pulse laser light must always be kept in a longitudinal mode-locked state. I couldn't keep it.

The present invention was proposed in order to solve the problems of the prior art, and its purpose is to create a control system that can always maintain the output pulsed laser light in a longitudinal mode-locked state by injection. The object of the present invention is to provide an excellent pulse laser device having the following characteristics.

[Structure of the Invention] (Means for Solving the Problems) The pulse laser device of the present invention is a pulse laser device with an injection lock configuration, and a detection system that monitors a part of the output pulse laser light from the pulse laser device on the driven side. The present invention is characterized in that it includes a detector and a control section that performs tuning control of the pulse laser device on the driven side in accordance with a detection signal from the detector.

(Function) In the present invention having the configuration as described above, the output pulse laser beam from the pulse laser device on the driven side is constantly monitored by the detector, and based on the monitoring result, the control unit controls the output pulse laser light from the pulse laser device on the driven side. By feedback-controlling the pulse laser device, it is possible to always oscillate laser light that is longitudinally mode-locked.

(Example) Below, the pulse laser device of the present invention will be explained using the TEA shown in FIG.
- An example applied to a CO2 laser will be specifically described with reference to the drawings. Here, claims 1 to 3 are defined as
5 to 5, claim 4 to FIGS. 1 and 2, claim 5 to FIGS. 1 and 3, claim 6 to FIGS. Range 7 will be explained with reference to FIGS. 1 and 5. Note that the same parts as those in the prior art shown in FIG. 6 are denoted by the same reference numerals, and the description thereof will be omitted.

In FIG. 1, 20 is a photodetector for monitoring the pulsed slave laser light 12 reflected by the beam splitter 7, or an energy detector Tearly, which has a function of detecting only the pulsed laser. In the configuration shown in FIG. 1, a feedback loop is constructed using the detector 20, the computer 9, the piezo driver 10, and the piezo element 11. Note that the other parts are the same as the conventional example.

Then, the computer 9 determines the oscillation start time of the pulsed laser light waveform or energy waveform measured by the detector 20, moves the piezo element 11 accordingly, and calculates the oscillation delay time from the reference time to the oscillation start time. Change the resonator length so that it is the minimum. Thereby, the injection-locked slave laser light can always be oscillated. In this case, any of the times shown in FIGS. 2 to 5 is used as the oscillation start time.

Figure 2 is an example of determining the oscillation delay time from the optical waveform.The two points of 20% and 80% of the peak output are connected with a straight line, and the intersection of the straight line and the ground level is set as the oscillation start time, and the reference time is set as the reference time. (For example, the discharge start time) is the oscillation delay time.

Figure 3 is an example of determining the oscillation delay time from the optical waveform. A tangent is drawn from the 50% point of the peak output, the intersection of the tangent and the ground level is set as the oscillation start time, and the reference time (
For example, this is the case where the oscillation delay time is defined as the oscillation delay time (discharge start time).

Figure 4 is an example of determining the oscillation delay time from the optical waveform, where the oscillation start time is the time when the peak output occurs and the oscillation delay time is the time between the reference time (for example, the discharge start time). .

Figure 5 is an example of determining the oscillation delay time from the optical waveform, with the time at which 10% of the peak output occurs as the oscillation start time, and the time between the reference time (e.g. discharge start time) as the oscillation delay time. This is the case.

In the above embodiment, the rear mirror 5 is moved by the piezo element 11 to control the resonator length of the slave laser, but in the present invention, instead of the rear mirror 5, the output mirror 4 is moved, It is similarly applicable to a configuration in which the resonator length is controlled.

Further, the reference time is not limited to the discharge start time, and the oscillation start time can also be determined not only from the optical waveform but also from the energy waveform, and can be freely set.

Further, the present invention is not limited to the TEA-C02 laser of the above embodiment, but is applicable to all laser devices having an injection lock configuration, such as gas lasers and solid-state lasers.

As described in "Effects of the Invention" 2, in the pulse laser device of the present invention, in the injection lock type pulse laser device, a part of the output pulse laser light from the pulse laser device on the driven side is monitored, and this detection is performed. By performing tuning control of the pulsed laser device on the driven side according to the signal, the injection lock, which previously did not lock stably, can be fixed.
Since it can be applied stably even when the number of repetitions increases, it is possible to always obtain output pulsed laser light that is longitudinally mode-locked by injection.
You can get excellent results.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing one embodiment of a pulse laser device according to the present invention, FIGS. 2 to 5 are waveform diagrams showing different setting examples of oscillation start times, and FIG. 6 is a circuit diagram showing an example of a pulse laser device according to the present invention. FIG. 2 is a circuit diagram showing an example of a laser device. 1... Master laser, 2... Master laser light,
3... Discharge part, 4... Output mirror 5... Rear mirror 6... Injection mirror, 7... Beam splitter, 8... Detector, 9... Computer,
10... Piezo driver 11... Piezo element,
12...Slave laser light, 13...Output side interference output, 14...Transmitted master laser light, 15...
Transmission side interference output, 20...detector.

Claims (8)

[Claims] (1) A pulsed laser device on the driving side and a pulsed laser device on the driven side are provided, and a weak pulsed laser beam is incident from the pulsed laser device on the driving side to the pulsed laser device on the driven side,
In a pulsed laser device with an injection lock configuration in which a pulsed laser device on the driven side oscillates an intense pulsed laser beam having the same wavelength (longitudinal mode-locked) as the pulsed laser beam on the driving side, the pulsed laser device from the pulsed laser device on the driven side 1. A pulsed laser device comprising: a detector that monitors a portion of the pulsed laser beam; and a control section that performs tuning control of a driven-side pulsed laser device in accordance with a detection signal from the detector. (2) The control unit performs tuning control by minimizing the oscillation delay time from the reference time of the output light waveform or output energy waveform of the pulsed laser light to be monitored to the oscillation start time of the pulsed laser device on the driven side. The pulse laser device according to claim 1, wherein the pulse laser device performs the following steps. (3) The control unit changes the resonator length of the pulsed laser device on the driven side by the adjusting means, and performs feedback control so as to always be in a longitudinal mode-locked state. Pulsed laser equipment. (4) The pulsed laser device according to claim 3, wherein a piezo element is used as an adjusting means for changing the resonator length of the pulsed laser device on the driven side. (5) The control unit sets the oscillation start time at the intersection of the ground level and a straight line connecting two appropriate points of the output light waveform of the pulsed laser light to be monitored or the rising edge of the output energy waveform, and starts this oscillation from the reference time. 2. The pulse laser device according to claim 1, wherein tuning control is performed using the time up to the time as an oscillation delay time. (6) The control unit sets the oscillation start time at the intersection of the ground level and the tangent of the output light waveform of the pulsed laser light to be monitored or an appropriate point of the rising edge of the output energy waveform, and from the reference time to this oscillation start time. 2. The pulse laser device according to claim 1, wherein tuning control is performed using oscillation delay time. (7) The control unit performs tuning control by setting the time when the output light waveform or output energy waveform of the pulsed laser beam to be monitored reaches its peak as the oscillation start time, and setting the time from the reference time to this oscillation start time as the oscillation delay time. The pulse laser device according to claim 1, characterized in that: (8) The control unit sets the time when the output light waveform of the pulsed laser light to be monitored or the rising part of the output energy waveform exceeds an arbitrary output threshold as the oscillation start time;
Claim 1, characterized in that tuning control is performed using the oscillation delay time from the reference time to this oscillation start time.
The pulse laser device described in Section 1.