JPH05121814A - Laser oscillator using injection method - Google Patents

Abstract

PURPOSE:To provide a laser oscillator by using an injection method capable of stably producing a laser beam of high quality and large output having a waveform subjected to injection locking regardless of external influences such as heat and preferably used at general industrial levels. CONSTITUTION:A part of a laser beam 21 from a master laser oscillator 1 is divided to obtain a monitor beam 22 by a dividing means 4. The monitor beam 22 is made incident on a monitor means 9 while periodically blocked by a chopper means 14, and an output monitor signal is generated by a monitor signal generating means 13. By a synchronizing signal generating means 16, a slave laser oscillator 2 is triggered in synchronization with the chopper means 14. A micro-driving means 7 is controlled by a control means 17 on the basis of the output monitor signal, and the resonator length of the slave laser oscillator 2 is adjusted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection type laser oscillator, and more particularly to the structure of a laser device and an injection lock system using the same.

[0002]

2. Description of the Related Art Conventionally, in a pulsed pump laser oscillator,
As a method of obtaining high-quality laser light with a single frequency,
The injection locking method is known in the academic field. In this method, a driving side laser oscillator and a driven side laser oscillator, which continuously oscillate at a single frequency by a known means, are combined, and a weak seed laser beam is introduced from the driving side laser oscillator to the driven side laser oscillator. This is a method of obtaining a strong laser beam of the same quality as the laser beam on the driving side by using the gain of the strong laser excitation region of the side laser oscillator. Generally, as a scientific term, the driving-side laser oscillator is called a master laser, and the driven-side laser oscillator is called a slave laser. Therefore, in the following description, these academic terms will be mainly used.

FIG. 3 is a block diagram showing an example of an injection type laser oscillator which has been used in the field of conventional academic research. First, the configuration of this laser oscillator will be described below. In FIG. 3, 1 is a master laser and 2 is a slave laser. The oscillation longitudinal mode of the master laser 1 is single, and the stabilizer 3 is provided to stabilize the longitudinal mode.

The slave laser 2 reflects a part of the laser light 21 emitted from the master laser 1 and introduces it onto the optical axis of the resonator of the slave laser 2, and an output mirror 5 constituting the resonator. And rear mirror 6
have. In this case, the injection mirror 4
Are arranged on the axis of the laser light 21 emitted from the master laser 1, and the output mirror 5 and the rear mirror 6 are arranged so as to face each other with a strong laser excitation region inside the slave laser 2 interposed therebetween. There is.

The output mirror 5 or the rear mirror 6 has a laser beam of the master laser 1 and a slave laser 2 introduced therein.
A piezo element 7 for controlling the cavity length for tuning the longitudinal mode with the cavity length and the piezo driver 8 for driving the piezo element 7 are provided. In the figure, the piezo element 7 and the piezo driver 8 are provided on the rear mirror 6 side as an example.

On the other hand, on the axis of the laser light 21 emitted from the master laser 1, a power meter 9 is arranged so as to sandwich the injection mirror 4, and a laser light (monitor light) 22 which has passed through the injection mirror 4 is provided. Is input to monitor the output of the laser light 21 from the master laser 1. Further, a beam splitter 10 that divides the laser light into two is arranged on the axis of the laser light 23 emitted from the slave laser 2.

Further, a detector 11 for detecting the waveform of the laser light is arranged on the axis of a part of the laser light 24 reflected by the beam splitter 10. The transient recorder 12 is connected to the detector 11. The transient recorder 12 is the detector 1
It is a device that monitors whether the waveform of the laser light detected by 1 has a single frequency or whether the master laser and the slave laser are out of synchronization and has a beating waveform.

Next, the operation of the laser oscillator having the above structure will be described. That is, in the master laser 1, a very high quality laser beam, although weak, is produced by various methods such as using a grating and an etalon. However, in such a master laser 1, a very delicate optical element is used, and since these optical elements do not have resistance to a large-power laser beam, a large output cannot be obtained.

Therefore, with the configuration as shown in FIG. 3, a weak laser beam 21 from the master laser 1 is introduced into the slave laser 2 to obtain a strong laser beam 23. That is, as shown in FIG. 3, when the weak laser light 21 from the master laser 1 is incident on the injection mirror 4, a part of it is introduced onto the resonator optical axis of the slave laser 2. Slave laser 2
The laser light introduced into the inside passes through the strong laser excitation region of the slave laser 2, grows in the resonator of the slave laser 2 by the gain of the excitation region, and becomes the strong laser light 23 to the outside. Is emitted.

[0010]

By the way, in the laser oscillator having the above configuration, when the weak laser light 21 from the master laser 1 is introduced into the slave laser 2 and the slave laser 2 is oscillated, Since the longitudinal modes of 1 and the slave laser 2 do not normally match and are slightly deviated, the laser light 23 emitted from the slave laser 2 has a beating waveform. This waveform is a part of the laser light 2 reflected by the beam splitter 10.
4 is detected by the detector 11 and monitored by the transient recorder 12.

A laser beam 2 having such a beating waveform
In order to make the waveform 3 locked with injection, a voltage is applied from the piezo driver 8 to the piezo element 7 of the slave laser 2, and the piezo element 7 is driven by this, and the resonator length of the slave laser 2 is changed. Change. On the other hand, the output of the laser beam 21 from the master laser 1 is monitored by the power meter 9, and the piezo element 7 is fixed when the value reaches a minimum value.

That is, when the injection lock occurs, the oscillation frequency of the master laser 1 and the slave laser 2
Since the longitudinal mode frequencies of the two coincide with each other, interference occurs, and the value of the power meter 9 that monitors the output of the laser light 21 of the master laser 1 decreases, so when the value of the power meter 9 is near the minimum value , The injection lock is applied. Therefore, when the value of the power meter 9 reaches the minimum value, as described above, the piezo element 7
By fixing, the laser light 22 having a waveform in which the longitudinal modes of the master laser 1 and the slave laser 2 coincide with each other and the injection lock is applied can be obtained.

However, in the apparatus configuration as shown in FIG. 3, a strong pulsed light from the slave laser 2 may enter the power meter 9 for the weak laser light from the master laser 1. As a result, there is a risk of damaging the power meter 9. Further, the power meter 9 cannot faithfully represent the power of a waveform such as pulsed light having a relatively fast rise and a quick fall, and the pulsed light is expressed like noise, so the master laser 1 There is also a drawback that the output of the laser beam 21 from the laser cannot be accurately monitored. Even if the above operation is performed in such a state, it is not possible to stably obtain a laser beam having a waveform with an injection lock.

Further, if the voltage of the piezo driver 8 is fixed as it is after the above operation, the resonator length of the slave laser 2 changes due to external influences such as a change in room temperature. As a result, the longitudinal modes of the master laser 1 and the slave laser 2 are deviated from each other, so that the laser light 23 emitted from the slave laser 2 has a beating waveform again.

The present invention was proposed in order to solve the problems of the prior art as described above, and its purpose is to provide a high-quality injection-locked waveform regardless of external influences such as heat. -To obtain a laser oscillator of an injection system, which can stably obtain a high-power laser beam and is suitable for use at a general industrial level.

[0016]

A laser oscillator according to the injection system of the present invention has a driving side laser oscillator and a driven side laser oscillator, and emits a weak seed laser beam from the driving side laser oscillator. A laser beam on the driving side is introduced into the driven side laser oscillator, and a gain of a strong laser excitation region of the driven side laser oscillator is used to obtain a powerful laser beam of the same quality as the driving side laser beam. In the injection type laser oscillator described above, a minute driving unit provided in the resonator of the driven-side laser oscillator and adjusting the resonator length, and a part of the driving-side laser light are split as monitor light. Splitting means, chopper means for periodically blocking the monitor light, and the monitor light incident through the chopper means, Monitor means for monitoring the output of the laser light, monitor signal generating means for generating an output monitor signal of the drive-side laser light from the output of the drive-side laser light monitored by the monitor means, and the chopper means. Synchronization signal generating means for generating a synchronization output signal of the above as a trigger signal of the driven side laser oscillator, and control means for inputting the output monitor signal and controlling the minute driving means based on the data. It is characterized by

That is, in the injection type laser oscillator of the present invention, the laser light from the master laser is incident on the monitor means through the chopper means, the trigger of the slave laser is driven in synchronization with the chopper means, and the laser is monitored. The resonator length of the slave laser is adjusted by feedback control based on the output of the laser light.

More specifically, as the dividing means, as described in the prior art, for example, an injection mirror for introducing the laser beam from the master laser into the flavor laser can be used as the dividing means. In addition to this, it is also possible to use a beam splitter. That is, in this case, the laser light emitted from the master laser is once split by the beam splitter, one of them is introduced into the slave laser, and the other is used as the monitor light. On the other hand, a power meter as described above is generally used as the monitor means.

[0019]

The operation of the present invention having the above construction is as follows. First, since the slave laser trigger is driven by the synchronous output signal of the chopper means for blocking the laser light (monitor light) from the dividing means, even if the injection mirror is used as the dividing means, the slave laser It is possible to reliably prevent the strong pulsed light from entering the monitor means. Therefore, there is no risk of damaging the monitoring means such as the power meter, and the output of the laser light from the master laser can be accurately monitored.

Therefore, in the present invention, the output signal of the output monitor signal can be obtained because the output signal of the monitor beam can be accurately generated by the monitor signal generating means from the output of the laser beam accurately monitored. Based on this, the fine driving means can be controlled by the control means, and the resonator length of the slave laser can be adjusted appropriately. By performing such an operation, it is possible to stably obtain a high-quality, high-power laser beam having a waveform locked with injection. Also, even if the cavity length of the slave laser changes due to external influences such as heat,
Since the above operation can be appropriately performed as necessary, it is possible to always obtain a high-quality, high-power laser beam having a waveform locked with injection.

[0021]

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2. Here, FIG. 1 is a configuration diagram showing an embodiment of a laser oscillator according to the injection method of the present invention, and FIG. 2 is a chopper blade and a chopper rotation number detector (synchronization signal generating means) in the laser oscillator of FIG.
It is explanatory drawing which shows the arrangement | positioning relationship with respect to the laser beam.

First, the structure of the laser oscillator shown in FIG. 1 will be described. In this embodiment, a continuous oscillation CO ₂ laser is used as the master laser (driving side laser oscillator) 1, and a slave laser (driven side laser oscillator) 2 is used as the slave laser (driven side laser oscillator) 2.
A pulsed TEA CO ₂ laser is used.
Further, the master laser 1 has a grating inside, and wavelength selection is performed. Further, the master laser 1 has a single oscillation longitudinal mode, and the stabilizer 3 is provided as a longitudinal mode stabilizing mechanism.

On the other hand, as is clear from comparison between FIGS. 1 and 3, the basic structure of this embodiment is the same as that of the prior art shown in FIG. That is, the slave laser 2 has an injection mirror (splitting means) 4 for introducing the laser light 21 from the master laser 1, an output mirror 5 and a rear mirror 6 which form a resonator. The rear mirror 6 has a piezo element (fine driving means) 7 for controlling the resonator length.
And a piezo driver 8 for driving the piezo element 7. Further, a power meter (monitoring means) 10 for monitoring the output of the laser light (monitor light) 22 transmitted through the injection mirror 4 and a beam splitter 10 for splitting the laser light 23 emitted from the slave laser 2 are provided. A detector 11 for detecting the waveform of the light 24 and a transient recorder 12 are provided.

In addition to the basic structure described above, the present embodiment further has the following structure. That is, an A / D converter (monitor signal generation means) 13 is connected to the power meter 9, and an output monitor signal is generated from the output of the laser light 21 from the master laser 1 monitored by the power meter 9. Is becoming

The injection mirror 4 on the axis of the laser light 21 emitted from the master laser 1 is also used.
Between the power meter 9 and the power meter 9, there is provided a chopper device (chopper means) 14 for periodically interrupting the laser light (monitor light) 22 transmitted through the injection mirror 4. The chopper device 14 includes a chopper blade 15, a device main body that controls the rotation speed of the chopper blade 15, and a chopper rotation detector 16 that outputs a signal in synchronization with the rotation speed of the chopper blade 15. The chopper rotation speed detector 16 outputs a synchronous output signal for opening / closing the chopper wing 15, and is connected to an external trigger of the slave laser 2.

The chopper device 14 is such that when one of the chopper wings 15 comes to the detection position of the chopper rotation speed detector 16, that is, as shown in FIG. Is set so that the wing 15 of the other chopper intercepts the laser beam 22 when it overlaps with the chopper rotation speed detector 16 arranged directly below the rotation shaft 15a. Then, in such a state, the chopper rotation number detector 16 outputs a synchronous output signal, and the synchronous output signal is input to an external trigger of the slave laser 2 to oscillate the slave laser 2.

Further, reference numeral 17 in the drawing denotes a computer (control means) connected to the A / D converter 13. This calculator 17
Generates a control signal based on the data of the monitor signal generated by the A / D converter 11, and is set to control the piezo driver 8 via the D / A converter 18 by this control signal. ing. The D / A converter 18 has a function of converting the control signal from the computer 17 into an analog signal.

When operating the laser oscillator of the present invention having the above-mentioned structure, the following operation is performed. That is, first, the laser light 21 from the master laser 1 is injected into the slave laser 2, and the chopper device 14 is set to a predetermined rotation speed.

In order to obtain a stable injection-locked waveform, the applied voltage of the piezo driver 8 is first changed from 0 to 6 V by a command from the computer 17. This corresponds to the amount of movement of the piezo element 7 having moved by more than a half wavelength of the laser wavelength. As described above, while the applied voltage of the piezo driver 8 is changed, the laser light 22 transmitted through the injection mirror 4 is incident on the power meter 9 while being periodically blocked by the chopper device 14, so that the power meter 9 causes The output of the laser beam 21 from the master laser 1 is monitored, an output monitor signal is generated by the A / D converter 13, and the data is sent to the computer 17. The calculator 17 calculates the amount of movement of the piezo element 7 when the output value becomes a minimum value, generates a control signal, and outputs the control signal via the piezo driver 8.
Is changed by a small amount, and the movement amount of the piezo element 7 is controlled so that the output value is always the minimum value.

In this case, in this embodiment, the external trigger of the slave laser 2 is driven in synchronization with the position of the chopper blades 15 of the chopper device 14, that is, in the state where the laser light is blocked. Therefore, the powerful pulsed light of the slave laser 2 does not enter the power meter 9. Therefore, there is no risk of damaging the power meter 9, and the output of the laser light 21 from the master laser 1 can be accurately monitored by the power meter 9.

Therefore, in the present embodiment, the output of the laser beam accurately monitored by the power meter 9 produces an accurate output monitor signal by the A / D converter 11, so that the computer 17 calculates the accurate output monitor signal. Control the piezo element 7 based on the output monitor signal data,
The cavity length of the slave laser 2 can be adjusted appropriately. By performing such an operation, it is possible to stably obtain a high-quality, high-power laser beam having a waveform locked with injection. In addition, even if the cavity length of the slave laser changes due to external influences such as heat, the above operation can be appropriately performed as necessary, so that high-quality, large-sized waveforms with injection locked waveforms are always available. Output laser light can be obtained.

The present invention is not limited to the above embodiment, and for example, the laser beam 2 of the master laser 1 is used.
In order to measure the intensity of 1 instead of measuring the laser beam 22 that has passed through the injection mirror 4,
A configuration is also possible in which 1 is divided by a beam splitter, one of them is used as monitor light, and the output of the laser light of the master laser 1 is measured by this monitor light. Further, instead of installing the piezo element 7 on the rear mirror 6, it is possible to install it on the output mirror 5.

[0033]

As described above, according to the present invention,
It is possible to stably obtain a high-quality, high-power laser beam having an injection-locked waveform regardless of external influences such as heat, and is an injection-type laser suitable for use at a general industrial level. An oscillator can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a laser oscillator by an injection method of the present invention.

FIG. 2 is an explanatory diagram showing an arrangement relationship of a chopper blade and a chopper rotation speed detector (synchronization signal generating means) with respect to laser light in the laser oscillator of FIG.

FIG. 3 is a configuration diagram showing an example of a conventionally used injection type laser oscillator.

[Explanation of symbols]

 1 ... Master laser (driving side laser oscillator) 2 ... Slave laser (driven side laser oscillator) 3 ... Stabilizer 4 ... Injection mirror (splitting means) 5 ... Output mirror 6 ... Rear mirror 7 ... Piezo element (fine driving means) 8 ... Piezo Driver 9 ... Power meter (monitoring means) 10 ... Beam splitter 11 ... Detector 12 ... Transient recorder 13 ... A / D converter (monitor signal generating means) 14 ... Chopper device (chopper means) 15 ... Chopper wings 16 ... Chopper rotation Number detector (synchronization signal generating means) 17 ... Calculator (control means) 18 ... D / A converter 21-24 ... Laser light

Claims (1)

[Claims] 1. A driving-side laser oscillator and a driven-side laser oscillator are provided, wherein the driving-side laser oscillator emits laser light that is a weak seed, and the driving-side laser light is introduced into the driven-side laser oscillator. , Configured to obtain a strong laser beam of the same quality as the laser beam on the driving side by using a gain of a strong laser excitation region of the driven-side laser oscillator,
In the injection-type laser oscillator, a minute driving unit provided in the resonator of the driven-side laser oscillator and adjusting the resonator length thereof, and a dividing unit for dividing a part of the driving-side laser light as monitor light. A chopper means for periodically interrupting the monitor light; a monitor means for injecting the monitor light through the chopper means to monitor an output of the laser light on the driving side; and a monitor means monitored by the monitor means. From the output of the laser light on the driving side, a monitor signal generating means for generating an output monitor signal of the laser light on the driving side, and a synchronous output signal of the chopper means, a synchronizing signal for generating the trigger signal of the driven side laser oscillator. Generating means and the output monitor signal are input, and the minute driving means is based on the data. And a control means for controlling the laser.