JPS6220386A - Pulse laser device - Google Patents

Abstract

PURPOSE:To make waveform characteristics excellent and to generate laser light highly efficiently, by providing a slave oscillator and an injecting laer oscillator in a resonator, injecting the generated laser ligth in the slave oscillator, and performing injection lock oscillation. CONSTITUTION:A slave oscillator has an exciting part 11 comprising an electron-beam excited KrF laser. A semitransparent mirror 12 and a front mirror 13 are arranged on both sides of the exciting part 11. A Faraday rotor 14 is provided between the front mirror 13 and the exciting part 11. The Faraday rotor 14 has a feature that a polarizing rotary angle is added even when output light is imputted in the reverse direction. Therefore, pulses are generated only by the rotation of the polarizing surface by the Faraday rotor 14. There s not loss in the laser output. The linearly polarized laser light, whose pulse width is shorter than the reciprocating time of the light in the resonator of the slave oscillator, is generated. The laser ligth is injected in the slave oscillator, and the injection lock oscillation is performed. The waveform characteristics becomes excellent and the pulse laser light can be generated highly efficiently in this simple structure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a pulsed laser device that generates pulsed laser light.

(Technical background of the invention and its problems) In recent years, much research has been carried out using pulsed laser light on nonlinear optics and its application to laser radar, laser distance measurement, high-speed photography, precision laser machining, etc. However, conventionally known pulsed laser devices used in such research include those that generate pulsed laser light by using, for example, a Q-switch or internal optical modulation. .

However, devices that use Q-switches require high voltage to drive switching elements such as Pockels cells, which increases the size of the device and makes it difficult to obtain reproducible optical pulse waveforms. There were drawbacks. Those that perform unidirectional optical modulation are difficult to obtain stable oscillation due to competition between pulses, and cannot generate efficient pulses due to variable i1 loss.

[Purpose of the invention]

The present invention makes it possible to generate an optical pulse train without using a switch and without performing loss modulation, thereby generating pulsed laser light with a simple configuration, good waveform characteristics, and high efficiency, and generating 1q pulses. The purpose is to provide a laser device.

[Summary of the invention]

In order to achieve the above object, the present invention includes a 7J slave oscillator in which a Faraday rotator is inserted in a resonator, and an injection laser oscillator, and the light of the slave oscillator is transmitted from the injection laser oscillator. A linearly polarized laser beam with a pulse width shorter than the round trip time is generated, and this laser beam is injected into the slave oscillator to perform injection-locked oscillation.

[Embodiments of the invention]

FIG. 1 is a schematic diagram of a pulse 1 noser device according to an embodiment of the present invention, and numeral 10 in the figure indicates a slave oscillator. This slave oscillator has an excitation section 11 made of an electron beam pumped KrF laser, and a semi-transparent mirror 12 and a front mirror 13 are disposed at both ends of the excitation section 11, respectively. A Faraday rotator 14 is inserted between the two. Note that 15 and 16 are apertures. The excitation section 11 is equipped with a switch section 20, and a trigger laser oscillator 17 is connected to this switch section 20.
Trigger laser light is supplied from the mirrors 18 and 19 through reflecting mirrors 18 and 19, thereby causing oscillation at a constant timing. still,
A control circuit 21 generates a timing signal for the i-Riga laser oscillator 17.

On the other hand, in the Faraday rotator 14, the plane of polarization of light propagating in a material to which a magnetic field parallel to the direction of travel of the light is applied is determined by the following formula: (1) is the Verdet constant of the material, H is the strength of the magnetic field applied in the direction of travel of the light, This method utilizes the so-called Faraday effect, in which the material length is rotated by an angle expressed by the relationship θ-VHL, and has the characteristic that the polarization rotation angle is added even when the output light is incident in the opposite direction. have For example, when the rotation angle of the Faraday rotator is set to 45 degrees, when a linearly polarized injection laser beam is input into the resonator as shown in FIG. 2, this injection laser beam passes through the Faraday rotator 14. When the plane of polarization is rotated by 45 degrees, the plane of polarization is further rotated by 45 degrees when it is reflected by the front mirror 13 and enters from the opposite direction, resulting in a 90 degree angle to the injected light.
It will be rotated.

The laser device of this embodiment also includes a mask oscillator 22 for generating injection laser light. This mask oscillator 22 uses a short pulse oscillation discharge type KrF laser.
In accordance with the timing instructed by the control circuit 21, an injection laser beam whose pulse width is shorter than the optical round trip time of the resonator of the slave oscillator 10 is generated. The injected laser beam passes through reflecting mirrors 23 and 24, and then is linearly polarized by a polarization separator 25 that separates it into two i-line light components, and is injected into the slave oscillator 10.

With such a configuration, for example, the slave oscillator 10
Assume that the optical reciprocating distance of the resonator is 1'2 ris, and in this state, when the master oscillator 22 generates an injection laser beam with a pulse width of 4 ns and injects it into the slave oscillator 10, this injection laser beam enters the excitation section. After being amplified in a laser medium 11, the light passes through a Faraday rotator 14, where it is given a constant rotation θ of the plane of polarization. When the laser beam given the rotation of the polarization plane is reflected by the reflecting mirror 13 and enters the Faraday rotator 14 from the opposite direction, the laser beam is given a rotation of the polarization plane of approximately θ, thereby causing the injection The polarization plane of the light is rotated by 2θ, and after being amplified by the laser medium of the excitation unit 11, the light is outputted via the semi-transparent mirror 12. On the other hand, the laser beam reflected by the semi-transparent mirror 12 undergoes the same process as the first pulse laser beam, and the plane of polarization is further rotated by 20, and is output from the semi-transparent mirror 12 as the second pulse laser beam. Ru. At this time, the output levels of these output laser beams are substantially equal because they are not affected by attenuation or the like by the Faraday rotator 14 at all.

Similarly, the plane of polarization of the injected laser beam is rotated by 2θ by the Faraday rotator 14 each time it makes one round trip within the resonator of the slave oscillator 10, and is output from the semi-transparent mirror 12.

FIG. 3 shows Faraday rotation, with the rotation angle θ of the trochanter 14 being 45°,
An example of the waveform of the output E noser light is shown when the oscillation time width of the excitation unit 11 is 100 ns. Note that this output waveform is output 1. ,,/- out of the light (the same as t) and 180° co-rotated with the polarization separator',) 5)'-('''' Separation extraction l
3, which is denoted by ヮ, and (in the case of 2, injection 1) -
Even if we separate and extract the polarization planes of 90° and 270", the waveforms of the two opposites are shown in Figure 4. Figures 3 and 4
The waveform in the figure is Isunemo Injection 1 Nori°尤/) - Slay 1
Two round trips inside the resonator of the oscillator 10 (1-4 times required)
f) with a pulse interval corresponding to 24 ns), so q
Complementary i (relationship) Jl.

In this embodiment, the Faraday rotator 144 is inserted into the resonator of the Slave 7M resonator 10, and the injected laser beam with a pulse width shorter than the optical round trip time of the slave oscillator 10 is injected into the slave oscillator 10. One laser beam is injected from the laser beam oscillator 22 (due to injection-locked oscillation, the plane of polarization has a rotation proportional to the number of times that the laser beam reciprocates within the resonator of the laser beam oscillator 10). will be obtained.

At this time, the voltage inserted into the resonator is 1 = 1, which is a direct current.
1, and the pulses are generated by the Faraday cotrochanter 14 (only due to the co-rotation of the light plane, so it is similar to loss modulation) of the 4I:1 noser output. Therefore, a KrF laser, which is a non-storage type laser, can generate pulses efficiently without causing losses.
It is extremely suitable for use as a Rayleigh device for inertial nuclear fusion, which requires pulses of the same type as 1 or 4 before 0 ns.

It should be noted that the present invention is not limited to the above-mentioned embodiments (4). j゛Rotating f1 mirror 3
It consists of an unstable shaker with a V-arranged rear mirror 32.
The polarization separator 34 outputs the rate tr)ll; suppressed by -C as well as J': Qs, and in the above embodiment, the rotation angle of the one-knob 7 Radet rotator 14 is set to 45°. In this case, if the rotation angle is set to, for example, about 40', the output pulsed light will be set to λ, for example, as shown in Fig. 6. Can be modulated. 1 Furthermore, as the slave oscillator, a dye laser, solid-state laser, etc. may be used in addition to the KrF laser, and the master oscillator may also be a slave oscillator.
An appropriate laser may be selected depending on the frame of the oscillator.

In addition, slave oscillator configuration) equipment application furrows, etc.
J and C can also be implemented with various modifications without departing from the gist of the present invention.

〔Effect of the invention〕

As detailed above, according to the present invention, a slave oscillator in which a Noah Arab rotor is inserted in a resonator is provided, and an injection laser oscillator is also provided, and the resonance of the L-distributed slave oscillator from this injection laser oscillator. A switch is used by generating linearly polarized laser light with a pulse width shorter than the light reciprocation time of the device, and injecting this laser light into the slave oscillator to cause injection oscillation. Optical pulse train without loss modulation
〇- It is possible to generate 7, this t'+, L: A pulse laser device with a simpler configuration, good waveform characteristics, and can generate pulse 1 noser light at a high da 1 rate. Can you provide?

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a pulsed laser device according to an embodiment of the present invention, Fig. 2 is a schematic diagram used to explain the operation of the Noah Arab rotator, and Figs. 3 and 4 are examples of the waveform of the output pulsed light. FIG. 5 is a waveform diagram showing another embodiment of the present invention.
FIG. 6 is a schematic diagram of a slave oscillator that performs t';i-. FIG. 6 is a waveform diagram of output pulsed light obtained by another embodiment of the present invention. 10...Slave oscillator, 11...Excitation section, 12.
... Semi-transparent mirror, 13.33... Forward mirror, 14... Faraday rotator, 15.16... Aperture, 17...
Trigger 1 nose oscillator, 1B, 19, 23, 24...
Reflector, 20... switch section, 21... control circuit,
22... Master oscillator, 25... Polarization separator, 32
... Rear mirror, 34... Polarization separator.

Claims (3)

[Claims] (1) A slave oscillator in which a Faraday rotator is inserted into the resonator, and a linearly polarized laser beam with a pulse width shorter than the optical round trip time of the resonator is injected into the slave oscillator and the injection is locked into the slave oscillator. A pulsed laser device comprising an injection laser oscillator for oscillating. (2) The pulse laser device according to claim (1), wherein the slave oscillator uses an unstable resonator as a resonator. (3) The pulse laser device according to claim (1), wherein a magnetic field is applied to the Faraday rotator to rotate its deflection plane by 45° each time the injected laser beam passes through.