JP2001308426A - Pulse laser oscillating method and oscillating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pulse laser oscillating device where the pulse width of an oscillating laser light beam is shortened and the pulse laser light beam of high peak power can be oscillated. SOLUTION: A Q switch element 5 and a cavity damp element 10 formed of electro-optic crystal are arranged between resonators constituted of two high reflection factor mirrors 3 and 14, and a 1/4λvoltage is applied to the Q switch element 5. Thus, it is functioned as a 1/4λ board and Q switch oscillation is performed. When the light intensity becomes maximum, the 1/4λ voltage is applied to the cavity damp element 10 and it is functioned as the 1/4λ board so as to perform cavity damping. The pulse laser light beam of a high peak level can be obtained by taking out the laser beam in a cavity at a stretch to an outer part through a polarizing beam splitter 11.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse laser oscillation method.
In particular, the present invention relates to a solid-state laser pumped by a semiconductor laser.
Short pulse laser light with high peak power using
Causes laser ablation and laser light waves
It is useful to apply when performing length conversion. 2. Description of the Related Art A semiconductor laser pumped solid-state laser device has a hole.
Material processing such as drilling, cutting, welding, exposure and surface modification,
It is applied to all processing such as surface treatment such as king, etc.
Generate pulsed laser light and use it
That is being done. Here, the semiconductor laser pumped solid-state laser
When using a laser device to obtain pulsed laser light,
Since the pump power of the body laser is small,
To obtain an output pulse laser beam with large peak power
I have. That is, a laser medium is excited by an excitation medium.
If you continue, the population inversion will increase and the loss of the resonator will be reduced.
Laser oscillation occurs when the gain of the laser exceeds the gain. This
Before the laser oscillation occurs, increase the loss of the resonator further.
If you do, the population inversion (population distribution density) will increase,
The loss is so great that laser oscillation does not occur. This state
When the loss is rapidly reduced in a short period of time,
Since the gain is large, laser oscillation occurs in a short time.
This is a pulse with small pulse width and large energy
Output. This is called Q-switch oscillation. FIG. 12 shows a conventional technique capable of performing Q-switch oscillation.
FIG. 2 is a block diagram showing a pulse laser oscillation device according to a surgical operation.
You. The pulse laser oscillation device is a semiconductor laser pumped solid
It is formed by a laser device. As shown in the figure,
The laser medium 1 is formed of a YAG laser rod or the like,
Laser light is emitted using the semiconductor laser 2 as an excitation light source.
High reflectivity mirrors 3 are provided on both end faces of the laser medium 1, respectively.
And a partial reflection mirror 4 are provided.
Is formed. Space (cavity) sandwiched between resonators
Inside, a Q-switch element 5 formed of an electro-optic crystal is biased.
Optical beam splitter 6 and 1/4 wavelength (hereinafter referred to as λ)
I do. ) It is arranged together with the plate 7. Here, the semiconductor laser
The user 2 operates in CW (continuous wave) or Q-
CW (quasi-continuous wave) operation is performed. Also, the Q switch element 5
Was supplied with a pulse voltage of 1 / 4λ by the high voltage pulser 9.
At this time, it functions as a λλ plate. In addition, polarized beams
The splitter 6 transmits P-polarized light and reflects S-polarized light.
Used. In such a pulse laser oscillation device, a half
Excitation of the laser medium 1 by the excitation light of the conductor laser 2
Then, light is emitted from the laser medium 1. This synchrotron radiation
The S-polarized light component is reflected by the polarization beam splitter 6.
Is discharged outside. On the other hand, the P-polarized light component of the linearly polarized light
Represents a high reflectance through the Q switch element 5 and the １ ／ λ plate 7
The light enters the mirror 3 and is reflected by the high-reflectance mirror 3.
The polarization beam is again transmitted through the ４λ plate 7 and the Q switch element 5.
To the beam splitter 6. Here, the Q switch element 5
When no voltage is applied, the polarization beam splitter
The P-polarized light transmitted through 6 only passes through here
Is reflected by the high-reflectance mirror 3 and reciprocates on the λλ plate 7
By doing so, S-polarized light is obtained. This S polarized light is Q switch
The polarization beam splitter 6 is reached via the element 5 where
It is reflected and discharged outside. That is, in such a state
Laser oscillation occurs due to large loss in the cavity.
Not. On the other hand, the high-voltage pulser 9
(A waveform of which is shown in FIG. 13A).
And the Q switch element 5 function as a １ ／ λ plate. this
As a result, the P-polarized light transmitted through the polarization beam splitter 6 is Q-split.
By reciprocating between the switch element 5 and the λλ plate 7,
Rotate to P-polarized light. This P-polarized light is a polarized beam split
The laser medium 1 after passing through the light source 6 and reciprocating in the resonator.
Amplified. As a result, the loss decreases rapidly,
The gain of the laser increases accordingly, and the laser medium 1
Large peak after a certain delay time determined by loss etc.
A short-pulse laser beam with
Show. ) Is transmitted through the partial reflection mirror 4 and taken out.
It is. In other words, a large peak value due to the Q switch oscillation
Is obtained. [0007] However, as described above,
Obtaining pulsed laser light with a semiconductor laser pumped solid-state laser device
In a pulse laser oscillation device, the excitation power of the semiconductor laser 2 is
Since the power is small, the gain is shared using the Q-switch element 5.
Extremely high gain in the laser medium 1 even when stored in the vibrator
Difficult to form, resulting from such low gain
The resulting laser light has a relatively long pulse width. sand
In other words, laser ablation processing or changing the wavelength of laser light
When switching, a short pulse laser beam with a pulse width of about 10 nS
Is preferable, but the half of the prior art as described above is used.
In a solid-state laser device excited by a conductor laser, Q-switch oscillation
Even if it is performed, the pulse width is about several tens to 100 ns.
Therefore, it is not possible to use a pulse laser beam with a sufficiently short pulse width.
could not. To shorten the pulse width, the pulse
Laser light is reduced by shortening the cavity length of the laser oscillator.
Reducing the time for reciprocating between resonators and semiconductor for excitation
It can also be realized by improving the excitation output of the body laser 2.
However, there is a limit to shortening the pulse width, and 10 nS
It is extremely difficult to reduce
Was. Also, if the cavity length is shortened, the beam spreads
Beam quality degradation such as an increase in angle occurs.
In addition, the repetition rate of the laser
When the output of the body laser 2 is changed,
The gain achieved will also vary. Therefore, the laser beam output energy
If not only the energy but also the pulse width changes at the same time
The above problem also arises. The present invention has been made in view of the above prior art, and has been developed in consideration of a resonator.
Do not shorten the length or increase the power of the excitation light source.
To reduce the pulse width of the oscillation laser
Pulse laser emission capable of oscillating pulse laser light
It is an object to provide a vibration method and an oscillation device. [0010] The present invention for achieving the above object.
The configuration of the pulse laser oscillation method according to the present invention has the following features.
I do. 1) Excitation of laser medium by excitation light source
Then, the light radiated from this laser medium is reciprocally amplified by the resonator.
Laser oscillation method for obtaining pulsed laser light
Laser light between the high-reflectance mirrors on both sides of the laser medium.
Make the Q switch oscillate in a completely confined state,
Continue near the peak level of the pulsed light accumulated in the chamber.
Performed cavity dump and accumulated inside the resonator.
Pulse by instantaneously extracting energy to the outside
Obtaining laser light. According to the present invention, sandwiched between resonators
Laser light has become sufficiently large in the open space (cavity)
Light trapped in the cavity at the moment
Can be taken out. 2) The pulse laser emission described in 1) above
In the vibration method, the width is smaller than the spectrum width of the output laser light.
Continuous wave laser light is used as seed light, and this seed light enters the resonator.
Fire. According to the present invention, Q switch oscillation and key
The output laser that is extracted to the outside by the
Laser light having a spectrum width can be used. The structure of the pulse laser oscillation device is as follows.
Features a point. 3) a laser medium for exciting the laser medium
Resonator for reciprocating amplification of light emitted by light source and laser medium
Laser device for obtaining pulsed laser light with
High-reflectance mirrors on both sides of the laser medium
Q-switch element and cavity between resonators arranged
Disposes a dump element and completely closes the laser beam inside the resonator
Oscillates Q-switch oscillation in the embedded state and accumulates in the resonator
In the vicinity of the peak level of the pulsed laser light,
Activate the cavity dump device, and then perform cavity dump.
The energy stored inside the resonator is instantaneously
It is configured to be taken out. According to the present invention,
Space oscillated by Q-switch oscillation and sandwiched by resonators
In the cavity while being amplified reciprocally in the (cavity)
When the trapped laser beam becomes sufficiently large
Then, this laser light is instantaneously externally
Can be taken out. 4) The pulse laser emission described in 3) above
In a vibration device, a Q switch element and a cavity dump element
Are distributed on both sides of the laser medium,
Adjacent to each of the switch element and cavity dump element
Then, a polarization beam splitter is arranged, and Q switch oscillation
Laser light amplified by
That it can be output to In the present invention
When the Q switch is not operating, the polarization
Use a beam splitter to block laser light from going back and forth between resonators
On the other hand, the operation of the Q switch causes the laser
Reciprocal amplification of light is performed, which closes the cavity.
When the contained laser light becomes sufficiently large,
Operate the bite dump element and use the cavity dump
The laser light in the resonator can be taken out to the outside at once.
You. 5) The pulse laser emission described in 4) above
In a vibration device, a Q switch element and a cavity dump element
Each element is made of an electro-optic crystal. According to the invention
Then, both Q switch oscillation and cavity dump
Laser light generated in proportion to the voltage applied to the electro-optic crystal
Polarization state via phase difference generated in X-axis and Y-axis direction components
Can be realized by changing 6) Pulse laser emission described in 4) above
Q-switch element made of acousto-optic crystal in vibration device
That you did. According to the present invention, the Q-switch oscillation generates
What is achieved by refracting the optical axis with a crystal
Can be. 7) Pulse laser emission described in 4) above
In the vibration device, the spec
Seed laser emitting continuous-wave laser light smaller than tor width
The seed light output by this seed laser is
The splitter is configured to reflect and capture light toward the resonator.
Was it. According to the present invention, the spectral
An output pulse laser beam with a narrow width can be obtained. 8) The pulse laser emission described in 4) above
The vibration device is a solid-state laser device excited by a semiconductor laser.
When. According to the present invention, in the prior art, particularly high peak
Semiconductor lasers where it was difficult to obtain
Even if the laser is a pumped solid-state laser device,
To easily reach the desired high peak level.
it can. 9) The pulse laser emission described in 3) above
In a vibration device, a Q switch element, a cavity dump element
And polarization beam splitter on one side of laser medium
On the other hand, the laser light amplified by the Q-switch oscillation
Cavity dump and output to outside
That it was configured. According to the present invention, a machine similar to the above 4) is provided.
Function can be realized with one polarizing beam splitter.
Wear. 10) Any one of the above 3) or 9)
In the pulse laser oscillation device to be described,
Both the element and the cavity dump element are made of electro-optic crystal.
That it did. According to the present invention, Q-switch oscillation and
Each of the voltage dumps is compared to the voltage applied to the electro-optic crystal.
Occurs in the X-axis and Y-axis components of the generated laser light
It is realized by changing the polarization state through the phase difference.
Can be 11) Any one of the above 3) or 9)
In the pulse laser oscillation device to be described,
The element was made of an acousto-optic crystal. According to the present invention, Q
Switch oscillation causes the optical axis to be refracted by the acousto-optic crystal
This can be achieved. 12) The pulse laser described in 3) above
In an oscillator, a Q switch element and a cavity
Is formed by one electro-optic crystal, and this electro-optic
Q switch oscillation at rising of pulse voltage supplied to crystal
And the cavity dump
Have been configured to perform According to the present invention,
Q switch oscillation similar to that of 3) or 4), followed by
Making a cavity dump with one electro-optic crystal
Can be. 13) The pulse laser described in 10) above.
In the oscillation device, the voltage is applied to the cavity dump element.
Variable voltage magnitude or rise time of this voltage
Output laser light corresponding to the applied voltage.
Pulse width can be adjusted.
When. According to the present invention, obtained by a cavity dump element
The pulsed laser light becomes elliptically polarized light,
One of the polarization components is selected and output. 14) The pulse laser described in the above 12)
In the oscillation device, the voltage applied to the cavity dump element
Variable fall time of the pulse voltage
Output laser light pulse corresponding to the applied pulse voltage.
That it can be adjusted in width. Departure
According to the description, the pulse rate obtained by the cavity dump element is used.
Laser light becomes elliptically polarized light, and any of them
A polarization component is selected and output. 15) What is the above 3) or 9) to 14)
In the pulse laser oscillator described in any one of the above,
A string narrower than the spectrum width of the output laser light of the oscillation device.
A seed light laser that emits continuous wave laser light is added,
Seed light output from laser is resonated by polarization beam splitter
That it is configured to reflect and take in the side. According to the invention
Output pulse with a narrow spectral width
Laser light can be obtained. 16) What is the above 3) or 9) to 15)
One of the pulsed laser oscillators described in
A laser-excited solid-state laser device. According to the present invention
For example, in the prior art, particularly high peak level pulses
Semiconductor laser-pumped solid-state laser with difficulty in obtaining laser light
Easy peak level of output pulse even in equipment
To a desired high peak level. 17) What is the above 3) or 9) to 16)
In the pulse laser oscillation device described in any one of the above,
Narrower than the spectrum width of the output laser light of the oscillation device
Seed laser emitting continuous wave laser light and this seed laser
Polarized beam splitter that reflects the seed light output by the
And the seed light reflected by this polarizing beam splitter.
While rotating by a predetermined angle, the output laser light
This is transmitted through the optical beam splitter to the outside.
The output laser light also has a light rotating means that rotates a predetermined angle,
Seed light enters the resonator through the same optical path as the output laser light
That it can be made to be. According to the present invention
The seed light and the output laser light traveling in opposite directions.
It can be rotated by a predetermined angle by the rotation means, and
As a result of this rotation, the seed light and the output laser light are aligned on the same optical axis.
They can be prevented from interfering with each other. 18) The pulse laser described in 17) above
In the oscillator, the light rotating means is a Faraday rotator
And a half-wave plate. According to the present invention,
Seed light and output laser light traveling in opposite directions
Rotate a predetermined angle with the data and half-wave plate
The seed light and the output laser as a result of this rotation
So that light does not interfere with each other on the same optical axis.
Wear. Embodiments of the present invention will be described below with reference to the drawings.
This will be described in detail based on FIG. In each figure, the same as FIG.
Parts and parts that are the same in each figure are given the same numbers.
And duplicate description is omitted. <First Embodiment> FIG. 1 shows a first embodiment of the present invention.
Block diagram showing a pulse laser oscillation device according to an embodiment of the present invention.
FIG. As shown in FIG.
The laser oscillating device uses a pulse according to the prior art shown in FIG.
Q-switching element 5 between the resonators of the laser oscillation device, polarization
Along with the beam splitter 6 and 1 / 4λ plate 7,
Cavity dump element 10 for tea dump and polarized beam
This is the one in which the Msplitter 11 is added. Here,
The bitty dump element 10 and the polarizing beam splitter 11
Q switch element 5 and polarized beam with respect to laser medium 1
It is distributed on the opposite side of the splitter 6. Ma
The cavity dump element 10 is the same as the Q switch element 5.
Formed by the same type of electro-optic crystal
The filter 11 transmits P-polarized light in the same manner as the polarization beam splitter 6.
And reflect S-polarized light. cavity
A high-voltage pulse similar to the high-voltage pulser 9 is provided in the dump element 10.
A pulse １ ／ λ voltage is applied by the capacitor 10. 1/4
The cavity dump element 10 to which the λ voltage is applied is は
Functions as a λ plate. For electro-optic crystal, voltage is applied to the crystal
Has a primary electrical effect in which the internal refractive index changes in proportion to
This characteristic allows the x-direction and the
A phase difference occurs in the y-direction component. Therefore, the applied voltage
Controls the above phase difference by setting to an appropriate size
This is because the polarization state can be changed. The high voltage pulsers 9 and 10 are Q switch elements 5
And a pulse-like 1 / 4λ
The timing for applying the pressure is output by the master pulser 13.
Control with a trigger pulse. Specifically, the Q switch element
After oscillating the element 5 and oscillating the Q switch,
Cavity when pulsed laser light reaches peak level
Operate the dump element 10 to perform a cavity dump
Control at such timing. This is for example in a resonator
Detects laser light reciprocating through a photodiode with a photodiode
This makes it easy to control. Inspection at this time
The light is emitted by, for example, connecting a photodiode to the high-reflectance mirror 3,
By arranging it on the back of 14 etc., it leaks from these
Laser light can be used. Also, by Q switch oscillation
Whether the oscillating pulse laser beam is at the time of operation of the
The time it takes to reach the peak level from
Therefore, once this is measured, the high-voltage pulsar
Unique delay time between trigger pulses supplied to 9, 10
Is determined. Therefore, this delay time can be ascertained in a circuit.
You should keep it. In this embodiment, the light reciprocating between the resonators
Of the resonator mirrors are 100
% High reflectivity mirrors 3 and 14
You. The pulse laser oscillation device of this embodiment is
And a high voltage pulse is generated by the trigger pulse of the master pulser 13.
The pulse is applied to the Q switch element 5 by operating the
When a 1 / 4λ voltage (see FIG. 2A) is applied,
The same as the pulse laser oscillation device according to the prior art shown in FIG.
Laser light reciprocates between the high reflectance mirrors 3 and 14 in the same manner
And amplified. That is, Q switch oscillation occurs.
As a result, after a certain delay time, the laser in the resonator
Light (see FIG. 2 (b). The dotted line in the figure indicates the cavity
It is the waveform of the laser beam when there is no dump. ) Is sudden
It becomes pulse laser light that rises sharply. Next, the level of the pulse laser light is
The master pulser 13 trigger pulse
Operating the high voltage pulser 12 and the cavity dump element 1
A pulse-like １ ／ λ voltage (see FIG. 2C) is marked at 0.
Add. As a result, the Q switch oscillation
The laser light trapped inside the
It is taken out to the outside at a stretch via the data 11. That is,
Short pulse width with high peak due to cavity dump
(About 10 ns) pulsed laser light (see FIG. 2D)
Teru. Get) More specifically, the laser light is Q-switched.
Oscillation starts round-trip amplification between resonators to a certain degree
After a time, the laser output between the resonators becomes sufficiently large,
The output is amplified at a stretch using the gain accumulated during the period.
Conventionally, one of the resonator mirrors is partially reflected mirror 4 (FIG. 1).
See 2. ) As part of the laser light between the resonators
However, in this embodiment, the loss of laser light
10 to reduce and amplify the light intensity between resonators at once.
Using high reflectance mirrors 3 and 14 having a reflectance close to 0%
To reciprocate the laser light between the high reflectance mirrors 3 and 14
You. The laser beam performs round-trip amplification between the resonators.
In the meantime, the electro-optic crystal as the cavity dump element 10
No action is taken. As a result, the laser light
No change due to chemical crystal (cavity dump element 10)
Reciprocate between resonators without receiving. And the light intensity between the resonators
When the degree reaches the maximum, the electro-optic crystal (cavity
A high voltage pulse equal to the λ / 4 voltage is applied to the dump element 10).
When applied, this causes the laser medium 1 to
The polarization of the laser light traveling toward the mirror 14 changes, and
Folds at the mirror 14 and returns to the electro-optic crystal (cavity dump).
By passing through the element 10), the electro-optic crystal
The tip dump element 10) functions as a λ / 2 plate. this
As a result, the P-polarized laser light is rotated by 90 ° and turned into S-polarized light.
become. This S-polarized laser beam is a polarized beam splitter
The light is reflected at 11 and output to the outside. Electric light at this time
The operation of the crystal (cavity dump element 10) is
From the point of view of quality 1, the loss of light is large,
Stopping by this operation, the laser existing in the space between the resonators
Only the light is extracted to the outside. Accordingly
Thus, the pulse width of the laser light to be taken out becomes short, which is defined by t = 2 L / c L: cavity interval c: light speed, and the peak level is increased accordingly.
Will have the In practice, the electro-optic crystal
From the finite time of the applied voltage to the time t
The width increases. <Second Embodiment> FIG. 3 shows a second embodiment of the present invention.
Block diagram showing a pulse laser oscillation device according to an embodiment of the present invention.
FIG. As shown in FIG.
The laser oscillation device is different from the device shown in FIG.
The only difference is the position of the pump element 10. That is,
The bite dump element 10 is a laser medium in the resonator.
1 and the high-reflectance mirror 3,
It is arranged between the light beam splitter 6 and the light beam splitter 6. Such distribution
In this case, the polarization beam splitter 6
Polarizing beam splitter according to the first embodiment shown in FIG.
11 can have the same function. Sand
That is, the polarization beam splitter 6 operates when the Q-switch oscillates.
An element for securing an optical path for reciprocal amplification of laser light
Laser light to the outside during cavity dump
Functions as an element for reflection. The pulse laser oscillator of this embodiment is
, The same mode as the pulse laser oscillation device shown in FIG.
Pulse laser light with high pulse level and short pulse width
You. <Third Embodiment> FIG. 4 shows a third embodiment of the present invention.
Block diagram showing a pulse laser oscillation device according to an embodiment of the present invention.
FIG. As shown in FIG.
The laser oscillation device according to the second embodiment shown in FIG.
Remove the cavity dump element 10 of the device and replace
The Q-switch element 5 and the cavity dump element 10 (FIG. 3)
reference. ) Function. That is, Q
Since the switch element 5 is formed of an electro-optic crystal, 1
If a / 4λ voltage is applied, it functions as a λλ plate,
If no voltage is applied, the element simply passes light.
is there. Then, at the rise of the pulse-like 1 / 4λ voltage,
By functioning as a 1 / 4λ plate, Q switch
And a laser is applied in the same manner as in the first and second embodiments.
Performs round-trip amplification of light. Then, this 1 / 4λ voltage is suddenly increased.
If it can fall, Q
Since the polarized light passing through the switch element 5 is S-polarized light,
Take it out at once using the beam splitter 6
Can be. That is, the laser confined in the cavity
Light can be dumped to the outside by cavity dumping
You. For this reason, in this embodiment, the high-voltage rectangular wave pulsar
15 and the high-voltage rectangular wave pulser 15
A rectangular wave pulse voltage of λ voltage is supplied to the Q switch element 5.
It is configured so that: The rise of the rectangular pulse voltage at this time
The interval between rising and falling is defined by the first and second intervals shown in FIGS.
From the master pulsar 13 in the first and second embodiments
It corresponds to the interval between two trigger pulses to be transmitted.
Thus, the path that suddenly rises due to the Q-switch oscillation
Perform a cavity dump at the peak level of the laser light
be able to. The pulse laser oscillator of this embodiment is
5 (a) from the high voltage rectangular wave pulser 15.
A rectangular pulse is supplied to the Q switch element 5. This rectangle
After the rise of the shape pulse voltage, the Q-switch element 5
The passing light becomes P-polarized light and is reciprocally amplified between the resonators.
That is, Q-switch oscillation occurs and the laser between the resonators
After the light has been delayed for a certain period of time, as shown in FIG.
The line indicates the wave of the laser beam when there is no cavity dump.
It is a shape. Stand up as shown in). After that,
When the laser light reaches the peak, the rectangular pulse
Lower. As a result, the polarization beam beam is
The laser beam supplied to the splitter 6 becomes S-polarized light,
The light is reflected outside by the beam splitter 6. That is,
Vitity dump occurs and the high peak as shown in FIG.
Pulsed S-polarized laser light with a short pulse width
Output to the outside. FIGS. 6 to 8 show the cabinet of the apparatus shown in FIG.
The magnitude of the voltage applied to the
By making the rise time of the voltage variable,
Adjust the pulse width of the output laser light
It shows that you can do it. 6 to 8
(A) is the voltage applied to the cavity dump element 10
(B) is the waveform of the laser light generated by the Q-switch oscillation.
(Note that the dotted line in the figure indicates that there is no cavity dump.
It is a waveform of the laser light. ), (C) are cavity bars
The waveforms of the output laser light from the pumps are shown.
FIG. 6 shows that the cavity dump element 10 steeply rises.
FIG. 7 shows the cavity when the rising 1 / 4λ voltage is applied.
Less than 1 / 4λ voltage that rises sharply to the dump element 10
When a voltage is applied, FIG.
When a λλ voltage that slowly rises
Each waveform is shown. In the case of FIG.
(C) As shown in FIG.
An output pulse laser beam having the largest peak value is obtained. This
On the other hand, in the case of FIG. 7 and FIG.
As shown in the figure, the pulse width exceeds 10 ns and the peak value also
An output pulse laser beam that is reduced by that amount is obtained. As shown in FIG. 6 to FIG.
The peak value of the output pulsed laser light (pulse
The principle of controlling the width is as follows. This principle is illustrated in FIG.
It will be described based on. Cavity dump device as electro-optic crystal
10 indicates that the internal refractive index changes in proportion to the voltage application to the crystal.
And a phase difference is generated between the xy components in the xy directions of the laser beam.
Set the applied voltage to an appropriate level.
Control the phase difference and change the polarization state.
Can be Therefore, the cavity shown in FIG.
When a ４λ voltage is applied to the
The cavity dump element 10 is a laser beam reciprocating therethrough.
Function as a λ / 2 plate for P-polarized light ((1) in FIG. 9).
reference. ) Was rotated by 90 ° to S-polarized light (Figure
See 9 (3). ). Therefore, in this case,
The component is reflected outside by the polarization beam splitter 11
Is less than 1 / 4λ voltage, or 1 /
In the case of a transition period where the voltage gradually rises toward 4λ voltage
Becomes elliptical polarized light (see (2) in FIG. 9).
Only the S-polarized component of the polarized light is
It is reflected and taken out. On the other hand, the P polarization component is
After passing through the polarization beam splitter 11, the laser medium 1
(See FIG. 1). Where P-polarized elliptical polarized light
The ratio of the component to the S-polarized component is
Laser that is proportional to the applied voltage
The light peak value (pulse width) is proportional to the magnitude of the S-polarized component
The voltage applied to the cavity dump element 10
Continuous adjustment of peak value (pulse width) of output laser light by adjustment
Can be changed. Thus, the cavity of the apparatus shown in FIG.
The polarization mode of the laser light at the time of pumping is as shown in FIG.
Each polarized light in the figure is shown in the block diagram described at the top.
And polarized light at the same numbered parts. The above description is based on the first embodiment shown in FIG.
It is related to the device according to the form of
This is also performed in the device according to the second embodiment shown in FIG.
You can also. Further, according to the third embodiment shown in FIG.
The same adjustment of the output pulse width should
Can. However, in this case, the cavity dump element
5 when functioning as a cavity dump element
The falling edge of the pulse voltage
The laser beam is made elliptical polarization. <Fourth Embodiment> FIG. 10 shows a fourth embodiment of the present invention.
A block diagram showing a pulse laser oscillation device according to a fourth embodiment.
FIG. As shown in FIG.
The laser oscillation device according to the third embodiment shown in FIG.
A seed light laser is added to this device. Output ray
Making the spectral width of the light as narrow as possible
When a laser laser oscillator is used as a light source for an exposure system
And particularly important requirements when applied to wavelength converters.
Become. Output laser light and
Seed light can be injected into the resonator using the same optical path
The result is a pulsed laser oscillator according to the present embodiment.
is there. As shown in FIG. 10, the pallets according to the present embodiment
The laser oscillation device has the spectral width of the continuous wave
Laser beam injection mechanism and pulse laser oscillation device
So that this type of optical laser maintains resonance between
Added the function to maintain and control the distance between resonator mirrors
It is. This incidence mechanism is designed to produce continuous light
Seed light laser 16 that outputs laser light with a small torque width, polarization
Beam splitter 17, Faraday rotator 18 and 1
/ 2λ plate 19. Here, the seed light laser 16 is
Rays that are S-polarized light with a narrow spectral width of continuous wave light
The light is output to the polarization beam splitter 17. side
Optical beam splitter 17 reflects S-polarized light toward resonator
I do. Fara de rotator 18 and 1 / 2λ plate 19 are inserted
The emitted laser light is rotated by 45 ° in a predetermined rotation direction. Also,
The high reflectivity mirror 14 (or the high reflectivity mirror 3) may be used.
The position is formed to be movable by the resonator spacing control device 20.
And high reflection so that the seed light laser 16 maintains resonance.
The distance from the mirror 3 is adjusted.
You. As a result, as shown in FIG.
The S-polarized light output from the optical laser 16 is a polarization beam splitter.
The light is reflected by the shutter 17 and travels toward the resonator. This S-polarized light is
Rotated by 45 ° by the Arara de rotator 18
In step 9, it is rotated in the opposite direction by 45 °, returned to s-polarized light,
The light is reflected by the beam splitter 6 and enters the resonator.
On the other hand, the light exits from the cavity through the polarization beam splitter 6.
The emitted S-polarized output laser light is shown in FIG.
As shown, 45 ° on 1 / 2λ plate 19, Fara de Rotate
Is rotated 45 ° by the data 18 and becomes P-polarized light.
Since it is incident on the splitter 17, this polarization beam splitter
17 and is taken out. If you do this
In the optical path between the polarizing beam splitters 6 and 17, the seed light and the output
The polarization directions of the laser light and the laser light do not match. Accordingly
Therefore, two types of laser light interfere with each other even in the same optical path.
I will not do it. The pulse laser oscillation device of this embodiment is
Then, the seed light is introduced into the resonator and laser oscillation is performed.
The output laser light is specified by the wavelength of the seed light
High quality laser light having a narrow band spectral width is obtained. I
At this time, the linearly polarized light is located in front of the polarizing beam splitter 6.
Λ / 2 plate 1 for rotating the polarization direction of laser light by 90 °
9. Faraday rotator 1 that rotates the polarization direction by 45 °
Light composed of 8 and another polarizing beam splitter 17
Since the separation mechanism is located in the optical path of the output laser light,
By changing the polarization state of the light and output laser light,
Can be separated so as not to interfere with each other. The fourth embodiment is similar to the third embodiment.
It is a device in which a seed light incidence mechanism is added to the device according to the embodiment.
However, according to the second embodiment in exactly the same manner as this,
Adding a similar seed light injection mechanism to the device in a similar manner
Can be. That is, the seed light exiting the 1 / 2λ plate 19 is polarized.
So that it is taken into the resonator via the beam splitter 6
Just do it. In this case, it is completely the same as the fourth embodiment.
In the same way, the seed light is guided into the resonator through the
And a narrow spectral width output level.
Laser light can be obtained. Also, the seed light incidence mechanism is the first
Of course, it is also possible to add to the embodiment of
To obtain an output laser beam with a narrow spectral distribution
it can. However, the incidence of the seed light into the resonator in this case is
What is a polarizing beam splitter 11 that emits output laser light?
This is performed via a separately provided polarizing beam splitter 6.
Therefore, the seed light and the output laser light are separated on the coaxial optical path.
No mechanism is required. In the first to fourth embodiments, Q
The switch element 5 and the cavity dump element 10 are electrically
Although it was formed with a chemical crystal, it could achieve the same function.
If so, they can be used instead of these. In particular,
An acousto-optic device can be used as the Q switch device.
Wear. The polarization beam splitters 6 and 11 convert the P-polarized light.
The one that transmits and reflects S-polarized light was used.
There is no need to limit. Reflects P-polarized light and transmits S-polarized light
May be something. In short, the Q switch oscillation and the key following it
It would be good if it was configured to realize the activity dump operation
No. The present invention has been described in detail with the embodiments.
As described above, the invention described in [Claim 1] uses an excitation light source.
Light that excites the laser medium and radiates from this laser medium
Pulse laser to obtain pulsed laser light by reciprocally amplifying
In the laser oscillation method, the high reflectance mirror on both sides of the laser medium
Q switch with laser light completely confined between
Oscillation is performed and the peak of the pulse light accumulated in the resonator
Cavity dump is performed continuously near the level, and resonance occurs
Instantly extract energy stored inside the vessel to the outside
The pulse laser light is obtained by performing
Laser light is large enough in the space (cavity) between
Instantly light trapped in the cavity
Can be taken out. As a result, the pulse width becomes narrow.
Ablation processing,
Output pulse laser light suitable for wavelength conversion can be obtained.
You. The invention described in [Claim 2] is based on [Claim 2]
In the pulse laser oscillation method described in [1], the output laser
Seed light of continuous wave laser light narrower than the spectral width of laser light
Since this kind of light is incident on the resonator,
Take out by switch oscillation and cavity dump
The output laser can be laser light with a narrow spectral width.
Wear. As a result, the effect of the invention described in [Claim 1] is obtained.
In addition, a narrow spectrum width output laser light is required.
It is useful for wavelength conversion and exposure. According to a third aspect of the present invention, a laser medium is provided.
Quality, the excitation light source and the laser medium that excite it
Pulsed laser light with a resonator for reciprocating amplification of reflected light
In a pulsed laser oscillation device,
The Q switch is placed between the resonators with the high reflectance mirrors.
A switch element and a cavity dump element
Q-switch oscillation with light completely confined in resonator
The pulse laser light accumulated in the resonator.
Close the cavity level, operate the cavity dump element, and
And a cavity dump is performed.
Is configured to take out the energy
Therefore, it oscillates due to Q-switch oscillation and is sandwiched between resonators.
Cavity while being amplified in a reciprocating space (cavity)
The laser light confined in the
Instantaneously, this laser light is
Can be taken out to the outside. As a result, the pulse width becomes
Ablation processing is narrow and the peak value is large
Or to obtain an output pulse laser beam suitable for wavelength conversion.
it can. The invention described in [Claim 4] is based on [Claim 4
3] In the pulse laser oscillation device described in
Switch element and cavity dump element on both sides of the laser medium
While distributing and distributing, Q switch element and cavity
A polarizing beam splitter is placed adjacent to each of the dump elements.
A laser that has been amplified by Q-switch oscillation
Light can be cavity dumped and output to the outside
The Q switch is not operating
Is the transmission of laser light between the resonators by the polarization beam splitter.
While the Q switch operates, the
Reciprocal amplification of the laser beam at the
The laser light confined in Viti becomes large enough
To operate the cavity dump element
Pump out the laser light inside the cavity at once
be able to. As a result, the apparatus described in [Claim 3]
It has the same effect as. The invention described in [Claim 5]
4]. In the pulse laser oscillator described in
Switch element and cavity dump element
Q-switch oscillation and cavity damping
Are generated in proportion to the voltage applied to the electro-optic crystal.
Through the phase difference that occurs in the X-axis and Y-axis components of the laser light
To change the polarization state.
Wear. As a result, the predetermined Q switch oscillation function and
Tide dump function can be realized by solid crystal, and device configuration is easy
become. The invention described in [Claim 6] is based on [Claim 6
4]. In the pulse laser oscillator described in
Switch element is made of acousto-optic crystal.
The vibration is caused by refracting the optical axis with an acousto-optic crystal.
Can be realized. As a result, using acousto-optic crystals
The above-mentioned apparatus is described in [Claim 3] and [Claim 4].
The effects of the invention can be achieved. The invention described in [Claim 7] is based on [Claim 7]
In the pulse laser oscillation device described in 4),
Continuous wave narrower than the spectral width of the output laser light of the vibration device
A seed light laser that emits laser light has been added.
Seed light output by the laser is directed to the resonator side by a polarizing beam splitter.
Because it is configured to reflect and take in,
It is possible to obtain an output pulse laser beam with a narrow spectrum width.
it can. As a result, laser light with a particularly narrow spectral width
Required applications, such as wavelength converters and illumination for exposure
This is useful as a lighting device. The invention described in [Claim 8] is based on [Claim 8]
The pulse laser oscillation device described in [4] is a semiconductor laser.
Because it is a pumped solid-state laser device, in the prior art,
In particular, it was difficult to obtain high peak level pulsed laser light
The output of a semiconductor laser pumped solid-state laser
Easily set pulse peak level to desired high peak level
can do. As a result, ease of handling, etc.
Has many advantages, but the excitation energy is small.
As a result, an output pulse having a high peak value can be obtained.
Take advantage of semiconductor laser-excited solid-state laser devices
Thus, the use can be further expanded. By the way
Suitable for ablation and wavelength conversion
Can be done. The invention described in [Claim 9] is based on [Claim 9]
3] In the pulse laser oscillation device described in
Switch element, cavity dump element and polarizing beam splitter
Is placed on one side of the laser medium while the Q switch
Laser light amplified by vibration
Section so that it can be output to the
The same function as the invention described in Item 4] is performed by one polarizing bead.
It can be realized by a musplitter. As a result,
The same effect as that of the device described in claim 4 can be obtained by one polarization
With a small number of elements
You. Therefore, the cost of the device is reduced accordingly.
be able to. The invention described in [Claim 10]
The pulse according to any one of [3] or [9].
In a laser oscillation device, a Q switch element and a cavity
Since all of the dump elements are made of electro-optic crystal, Q
Both switch oscillation and cavity dump are electro-optical
X-axis of laser light generated in proportion to the voltage applied to the crystal and
The polarization state is changed through the phase difference generated in the Y-axis direction component.
It can be realized by doing. As a result,
Solid state Q switch oscillation function and cavity dump function
It can be realized by a crystal, and the device configuration becomes easy. The invention described in [Claim 11] is based on [Claim
The pulse according to any one of [3] or [9].
In the laser oscillation device, the Q switch element is
Q-switch oscillation is generated by acousto-optic crystal
Can be realized by refracting the optical axis more.
You. As a result, even in an apparatus using an acousto-optic crystal,
The effects of the invention described in [3] to [5] are exhibited.
be able to. The invention described in claim 12 is based on claim
Item 3] In the pulse laser oscillation device described in [3],
Switch element and cavity dump element with one electric light
Pulsed electric current, which is formed by
Q switch oscillation is performed at the rise of pressure.
Make a cavity dump at the fall.
As a result, the same Q-square as the invention described in [Claim 3] is obtained.
Switch oscillation and the subsequent cavity dump
It can be performed with a gas-optic crystal. As a result,
Cavity dump oscillation function and cavity dump function
High quality square wave pulse voltage that can be realized with the minimum number of elements
Is required, but the cost of the equipment is the most
It will be cheaper. The invention described in [Claim 13] is based on [Claim 13]
Item 10].
The magnitude of the voltage applied to the
By making the rise time of the voltage variable,
Adjust the pulse width of the output laser light
So that the cavity dump element
The pulse laser light obtained by the above becomes elliptically polarized light,
Any one of the polarization components is selected and output.
As a result, the polarization component extracted to the outside is adjusted by the applied voltage.
To adjust the peak value of the output laser light,
A laser with the optimum peak value and pulse width for the application
The light can be easily obtained. By the way, for processing etc.
Depending on the application, when a high peak value laser beam is required
Even so, if this is too high it will damage the work
May need to be addressed.
You. The invention as set forth in claim 14 is based on the claim
Item 12. The pulse laser oscillation device according to item 12,
Fall of pulse voltage applied to the activity dump device
By changing the time, the applied pulse voltage
The pulse width of the output laser light can be adjusted accordingly
With a cavity dump element
The pulsed laser light becomes elliptically polarized light,
One of the polarization components is selected and output. The invention described in [Claim 15]
[Claim 3] or any one of [Claim 9] to [Claim 14]
In the pulse laser oscillation device described in
Continuous wave laser narrower than the spectrum width of the output laser light of the device
Seed laser that emits laser light is added.
Of the seed light output by the polarization beam splitter to the resonator side.
Because it is configured to capture and shoot,
It is possible to obtain an output pulse laser beam with a narrow spectrum width.
Wear. As a result, laser light with a particularly narrow spectral width is required.
Required applications, such as wavelength converters and illumination for exposure
This is useful as a device. The invention described in [Claim 16] is based on [Claim
Item 3] or any of [Claim 9] to [Claim 15]
The pulse laser oscillation device described in one is a semiconductor laser
Because it is a pumped solid-state laser device, in the prior art,
In particular, it was difficult to obtain high peak level pulsed laser light
The output of a semiconductor laser pumped solid-state laser
Easily set pulse peak level to desired high peak level
can do. As a result, ease of handling, etc.
Has many advantages, but the excitation energy is small.
As a result, an output pulse having a high peak value can be obtained.
Take advantage of semiconductor laser-excited solid-state laser devices
Thus, the use can be further expanded. By the way
Suitable for ablation and wavelength conversion
Can be done. The invention described in [Claim 17] is based on [Claim 17]
Item 3] or any of [Claim 9] to [Claim 16]
In the pulse laser oscillation device described in one,
Continuous wave narrower than the spectral width of the output laser light of the vibration device
Seed laser that emits laser light and this seed laser
Polarizing beam splitter that reflects the applied seed light to the resonator side
And the seed light reflected by this polarizing beam splitter
And the output laser light is
This output level is transmitted to the outside through the
The laser beam also has light rotating means for rotating the laser beam by a predetermined angle, and the output laser
Seed light enters the resonator through the same optical path as the laser light
So that they can face each other in opposite directions.
Each of the seed light and the output laser light is separated by a predetermined angle by the light rotating means.
Can rotate, and as a result of this rotation,
Make sure that the output laser beams do not interfere with each other on the same optical axis.
Can be As a result, the light path for seed light input and
The optical path for output of the output laser light can be shared,
Introducing seed light into the laser cavity with no device configuration
Can be. The invention described in [Claim 18] is based on [Claim 18]
Item 17].
Rotating means is formed by Faraday rotator and half-wave plate
Seed light and output laser light traveling in opposite directions
At a predetermined angle with a Faraday rotator and a half-wave plate
Can rotate each other, and as a result of this rotation
And output laser beams do not interfere with each other on the same optical axis.
can do. As a result, the optical path for seed light input
And the optical path for output of the output laser light.
The fewest elements such as a ladder rotator and a half-wave plate
Configuration allows seed light to be introduced into the laser cavity
You.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a pulse laser oscillation device according to a first embodiment of the present invention. FIG. 2 is a waveform chart showing waveforms at various parts of the apparatus shown in FIG. FIG. 3 is a block diagram showing a pulse laser oscillation device according to a second embodiment of the present invention. FIG. 4 is a block diagram showing a pulse laser oscillation device according to a third embodiment of the present invention. FIG. 5 is a waveform chart showing waveforms at various parts of the device shown in FIG. 4; FIG. 6 shows a cavity dump element 10 of the apparatus shown in FIG.
FIG. 6 is a waveform chart showing waveforms of various parts when a λλ voltage that rises steeply is applied. FIG. 7 shows a cavity dump element 10 of the apparatus shown in FIG.
FIG. 5 is a waveform diagram showing waveforms of various parts when a voltage of less than a λλ voltage that rises steeply is applied. FIG. 8 shows a cavity dump element 10 of the apparatus shown in FIG.
FIG. 6 is a waveform diagram showing waveforms of various parts when a 立 ち λ voltage that gradually rises is applied. FIG. 9 shows the voltage applied to the cavity dump element in FIG.
FIG. 9A is an explanatory view conceptually showing a polarization mode in the cavity dump element 10 and the polarization beam splitter 11 in the case shown in FIG. 7A and FIG. FIG. 10 is a block diagram showing a pulse laser oscillation device according to a fourth embodiment of the present invention. 11A and 11B conceptually show a mode of polarization of a laser beam in the apparatus shown in FIG. 11, wherein FIG.
(B) is an explanatory view showing the polarization of the output laser light. FIG. 12 is a block diagram showing a pulse laser oscillation device according to the related art. FIG. 13 is a waveform chart showing waveforms at various parts in FIG. [Description of Signs] 1 Laser medium 2 Semiconductor laser 3 High reflectivity mirror 5 Q switch element 6 Polarization beam splitter 7 1 / 4λ plate 8 Drive power supply 9 High voltage pulser 10 Cavity dump element 11 Polarization beam splitter 12 High voltage pulser 13 Master pulser 14 High reflectivity mirror 15 High voltage rectangular wave pulser 16 Seed light laser 17 Polarizing beam splitter 18 Faraday rotator 19 1 / 2λ plate

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Claims (1)

Claims: 1. A pulsed laser oscillation method in which a laser medium is excited by an excitation light source and light emitted from the laser medium is reciprocally amplified by a resonator to obtain pulsed laser light. Q-switch oscillation is performed with the laser light completely confined between the high-reflectance mirrors, and a cavity dump is continuously performed near the peak level of the pulse light accumulated in the resonator, and accumulated inside the resonator. A pulsed laser beam oscillation method, wherein a pulsed laser beam is obtained by instantaneously taking out the emitted energy to the outside. 2. The pulse laser oscillation method according to claim 1, wherein a continuous wave laser beam having a narrower spectral width than an output laser beam is used as a seed beam, and the seed beam is made to enter the resonator. Laser oscillation method. 3. A pulse laser oscillation device for obtaining a pulsed laser beam having a laser medium, an excitation light source for exciting the laser medium, and a resonator for reciprocally amplifying light emitted from the laser medium, wherein a high reflection is provided on both sides of the laser medium. A Q-switch element and a cavity dump element are arranged between the resonators with the ratio mirrors, respectively, and the laser light is completely confined in the resonator so that Q-switch oscillation is performed and accumulated in the resonator. In the vicinity of the peak level of the pulsed laser light, the cavity dump device is operated, and the cavity dump is continuously performed.
A pulse laser oscillation device characterized in that energy stored inside a resonator is instantaneously extracted to the outside. 4. The pulse laser oscillation device according to claim 3, wherein the Q switch element and the cavity dump element are separately arranged on both sides of the laser medium, and the Q switch element and the cavity dump element are respectively disposed. A pulse laser oscillation device, comprising: a polarizing beam splitter disposed adjacent to a laser beam amplified by a Q-switch oscillation so that a cavity beam can be dumped and output to the outside. 5. The pulse laser oscillation device according to claim 4, wherein each of the Q switch element and the cavity dump element is formed of an electro-optic crystal. 6. The pulse laser oscillation device according to claim 4, wherein the Q switch element is formed of an acousto-optic crystal. 7. The pulse laser oscillation device according to claim 4, further comprising a seed light laser that emits a continuous wave laser light having a narrower spectral width than an output laser light of the oscillation device. 1. A pulse laser oscillation device characterized in that the seed light output from the laser beam is reflected by a polarization beam splitter toward a resonator and is taken in. 8. A pulse laser device according to claim 4, wherein the pulse laser oscillation device is a semiconductor laser pumped solid-state laser device. 9. The pulse laser oscillation device according to claim 3, wherein the Q switch element, the cavity dump element, and the polarization beam splitter are disposed on one side of the laser medium, and the laser light amplified by the Q switch oscillation. Characterized in that it is configured to be able to cavity dump and output the same to the outside. 10. The pulse laser oscillation device according to claim 3, wherein both the Q switch element and the cavity dump element are formed of an electro-optic crystal. Pulse laser oscillation device. 11. The pulse laser oscillation device according to claim 3, wherein the Q switch element is formed of an acousto-optic crystal. 12. The pulse laser oscillation device according to claim 3, wherein the Q switch element and the cavity dump element are formed of one electro-optic crystal, and the Q switch is turned on at the rise of a pulse voltage supplied to the electro-optic crystal. A pulse laser oscillation device configured to cause oscillation and perform a cavity dump at the fall of the oscillation. 13. The pulse laser oscillation device according to claim 10, wherein the magnitude of the voltage applied to the cavity dump element or the rise time of this voltage is made variable to correspond to the applied voltage. A pulse laser oscillation device characterized in that the pulse width of output laser light can be adjusted. 14. The pulse laser oscillation device according to claim 12, wherein the fall time of the pulse voltage applied to the cavity dump element is made variable so that the output laser light can be changed in accordance with the applied pulse voltage. A pulse laser oscillation device characterized in that a pulse width can be adjusted. 15. The pulse laser oscillation device according to claim 3, wherein the continuous wave width is smaller than the spectrum width of the output laser light of the oscillation device. 1. A pulse laser oscillation device comprising: a seed light laser that emits a wave laser light; and a seed light output by the seed light laser is reflected by a polarization beam splitter toward a resonator side to be taken in. 16. A pulse laser oscillation device according to any one of [3] or [9] to [15] is a semiconductor laser pumped solid-state laser device. Pulse laser device. 17. The pulse laser oscillation device according to claim 3, wherein the spectrum width of the output laser light of the oscillation device is narrower. A seed light laser that emits continuous wave laser light; a polarizing beam splitter that reflects the seed light output by the seed light laser to the resonator side; and a seed light that is reflected by the polarizing beam splitter is rotated by a predetermined angle. Light rotating means for rotating the output laser light by a predetermined angle so that the output laser light is transmitted through the polarization beam splitter to the outside; and the seed light enters the resonator through the same optical path as the output laser light. A pulsed laser oscillation device characterized in that it can be made incident. 18. The pulse laser oscillation device according to claim 17, wherein the light rotating means is formed by a Faraday rotator and a half-wave plate.