JPH02112294A - Laser wavelength stabilizer - Google Patents

Abstract

PURPOSE:To enable oscillation at a specified wavelength when reoscillating a laser and to stabilize a laser wavelength by diffracting a part of a laser beam during laser oscillation to control a spectroscope and by prediction- controlling the spectroscope based on a time constant of the spectroscope or a steady state during oscillation stop after stopping laser oscillation. CONSTITUTION:A photoresonator is constituted by arranging a total reflection mirror 2 and a partial reflection mirror 3 at both ends of a laser medium 1, and a laser beam 6 is produced. The laser beam 6 having a small oscillation wavelength width and an arbitrary wavelength lambda0 in a range wherein a gain exists is acquired by arranging a rough adjustment etalon 4 and a fine adjustment etalon 5 in an optical path of the photoresonator. An output wavelength of the laser beam 6 can be stabilized and controlled by controlling a voltage of a laser medium 1 in a laser oscillator or by controlling an angle or a mirror interval between the rough adjustment etalon 4 and the fine adjustment etalon 5. Stabilization of a wavelength and output becomes possible when a laser beam is narrow-banded, and, furthermore, constant stabilization of a wavelength can be realized even when laser oscillation and stop are repeated.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a laser oscillation stabilizing device, and in particular to a device for stabilizing laser oscillation in a narrow band excimer laser oscillator using a spectroscopic means such as a Fabry-Perot etalon. The present invention relates to a laser wavelength stabilizing device suitable for stabilizing output.

[Prior art] Figure 5 shows, for example, the literature journal rcAN, J, PHYsJOL.
, 63°214(1(185) J) is a schematic configuration diagram of a well-known narrowband laser oscillator shown in
1) is a laser medium, (2) and (3) are a total reflection mirror and a partial reflection mirror that are arranged to sandwich the laser medium (1) and generate a laser beam (6) by the optical pumping action between them. The mirror (4) is a rough adjustment etalon as a spectroscopy means arranged in the optical path of the laser beam (6) to coarsely adjust the wavelength of the laser beam by selectively transmitting the wavelength, (5) is a fine adjustment etalon which is disposed in the optical path of the laser beam (6) and serves as a spectroscopy means for finely adjusting the wavelength of the laser beam by selectively transmitting the wavelength.

The operation of this configuration will be explained next.

Normally, a laser medium (1) is surrounded by an optical resonator consisting of a total reflection mirror (2) and a partial reflection mirror (3), and the light is transmitted through the total reflection mirror (2) and the partial reflection mirror (3) of this optical resonator. ), the laser beam is amplified by 1 while reciprocating in the laser medium (1) many times and is extracted as a laser beam (6).

By the way, some laser oscillators, such as excimer lasers, semiconductor lasers, dye lasers, and some solid-state lasers, have a wide oscillation wavelength width, and the oscillation wavelength width can be increased by inserting a spectroscopic element into the optical resonator. It can be made narrower. For example, multiple Fabry-Perot etalons (
By using an etalon (hereinafter referred to as an etalon), it is possible to obtain a laser beam that is extremely close to monochromatic light.

In the example shown in FIG. 5, a case is illustrated in which two etalons, a rough adjustment etalon (4) and a fine adjustment etalon (5), are inserted into an optical resonator.

Now, FIG. 6 is a characteristic diagram explaining the principle of narrowing the laser emission amplitude. FIG. 6 (a) shows the transmission spectral characteristics of the rough adjustment etalon (4), and FIG. Figure 5) shows the transmission spectral characteristics of 5), and the laser gain profile (c) shows the spectral characteristics of the gain of the laser medium (1).
) indicate the spectral characteristics of the laser output after band narrowing.

Each peak position λm of the spectral characteristics of the rough adjustment etalon (4) has a wavelength expressed by λm=2·nd-00867m=(1). Here, n is 2 that constitutes the etalon.
The refractive index of the material between the two mirror surfaces, d is the distance between the two mirror surfaces, θ is the angle at which light enters the etalon, and m is an integer. (Some peaks correspond to differences in m. As is clear from equation (1), the peak wavelength of the peak can be freely changed by changing n, d, and θ.

On the other hand, the distance between the peaks is called the free spectral range (hereinafter referred to as FSR), and the distance between the peaks is FSR-λ/second
/2・nd-CO8θ...(2) It is shown as follows. In addition, the half-width Δλ of each peak is Δλ−F SR/F...
It is shown in (3). Here, F is called finesse,
This is determined by the performance of the etalon.

By the way, if there is no spectroscopic element in the optical resonator, the sixth
The light is amplified and becomes a laser beam within the range where the gain of the laser medium (1) shown in Figure (C) exists. At that time, make sure that the peak position λ,1 of the coarse adjustment etalon (4) is equal to the wavelength λ0 somewhere within the range where the gain exists, and that no other peaks other than λ11 occur within the wavelength where the gain exists. If d etc. are adjusted and determined in this way, a state with less loss will be realized only at λ0 due to the presence of the rough adjustment etalon (4), and light will be amplified and oscillated only in the vicinity of that wavelength.

Then, by making sure that there is only one peak, the minimum value of FSR is determined, and since the finesse F is determined by the performance of the etalon and is about 20 at most, the wavelength width can be narrowed using only the rough adjustment etalon (4). There are limits to what you can do.

Therefore, another fine adjustment etalon (5) is used. This spectral characteristic is, for example, as shown in FIG. 6(b). In this case, the peak wavelength λI12 may be made equal to λ 2 so that the FSR satisfies FSR2≧Δλ1.

As is clear from the above, in order to further narrow the wavelength width, it is sufficient to use one more etalon.

In this way, the laser beam originally output from the laser medium (1) with the spectral characteristics shown in FIG.
By using two etalons, oscillation occurs only in a narrow range centered around the wavelength λ0 where the peaks of each etalon overlap, as shown in FIG. 2(d). In reality, since the laser beam passes through the etalons many times during oscillation, the amplitude of the laser beam is 1/2 to 1/1 of the wavelength width determined by the two etalons.
becomes 0.

Although it is possible to narrow the wavelength width of a laser beam as described above, there is a problem with its stability. In other words, very short-term stability can be improved by improving the optical resonator or reducing the incident angle θ, but in the long term there are thermal problems, especially when the laser O beam passes through the etalon. Wavelength shift due to heat generation becomes a major problem.

FIG. 7(a) is an etalon transmission characteristic diagram showing an enlarged view of the spectral characteristics of the rough adjustment etalon (4), and the solid line depicts the spectral characteristics immediately after laser oscillation. by the way,
After the laser oscillates, the etalon is deformed by the heat generated by the laser beam (6).

Although this deformation does not deteriorate the characteristics of the etalon,
Changing the etalon gap length results in a shift in the wavelength range. The difference between the shift amount Δλ and the change in d due to the deformation of the etalon is Δλ−(λ/d) ・Δd... (
4) There is a relationship. Here, the direction of the wavelength shift is determined by the structure of the etalon, etc., and if a specific etalon is used, the wavelength will shift in one direction due to the heat generated by the laser beam. The state of the shift at that time is as shown by the broken line in FIG. 7<a>. FIG. 7(b) shows the temporal change in the amount of deformation Δ(d) of the etalon, and Δd changes according to the thermal time constant inherent to the etalon as the laser oscillates and stops.

Then, as Δd changes, the laser oscillation wavelength changes to the seventh wavelength.
It changes as shown in (C) of the figure.

On the other hand, a similar wavelength shift occurs regarding the fine adjustment etalon (5), but the situation is shown in FIG. 8(b) with respect to the wavelength shift of the coarse adjustment etalon (4) shown in FIG. 8(a). It comes to show. The wavelength shift amount of the fine adjustment etalon (5) is reduced by the amount that the etalon spacing d2 is larger than the etalon spacing dl of the coarse adjustment etalon (4).

Now, the problem in this case is that the peak wavelengths λml and λ3□ of the spectral characteristics of the two etalons are shifted.

At this time, the amount of light transmitted when both are stacked is λ, 1-λ1
As compared to case 2, it decreases as shown in FIG. 8(c). In other words, after the laser oscillator oscillates for a long time, the laser output shifts from λ0 to 22 wavelengths and the output decreases. Also, when the shift amount is large, as shown in Fig. 8(c)
As shown in FIG. 3, oscillation in other modes may also occur in the fine adjustment etalon (5).

[Problem to be solved by the invention] Conventional narrowband laser oscillation devices are configured as described above, and wavelength shifts are likely to occur due to thermal problems in the etalons, and differences in wavelength shift characteristics between the two etalons occur. This method has the problem that it can only be applied to low-power lasers with small thermal etalon deformation.

This invention solves the above-mentioned problems of the conventional technology, and makes it possible to stabilize the wavelength and output when the laser beam is made into a narrow band.Furthermore, the wavelength is always stabilized even when the laser oscillates and stops repeatedly. It is an object of the present invention to provide a laser wavelength stabilizing device that can be applied to high-output laser devices.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a laser whose oscillation wavelength is variable by a spectroscopic means such as a first Fabry-Perot etalon and a second spectroscopic means such as a Fabry-Perot etalon.・Laser oscillation means for emitting a beam, wavelength monitoring means for extracting a part of the laser beam emitted from the laser oscillation means and measuring the oscillation wavelength, and a first spectroscopic means based on the output of the wavelength monitoring means. a first control means for controlling and stabilizing the wavelength of the laser oscillation means; a power monitor means for extracting a part of the laser beam emitted from the laser oscillation means and measuring the laser output; A voltage control means for controlling the voltage applied to the laser medium, a second control means for controlling the second spectroscopy means, and a voltage control means for controlling the voltage applied to the laser medium based on the output of the power monitor means.
output stabilization means for stabilizing the output of the laser oscillation means by operating the control means in a time-minute square root manner; After measuring the amount and stopping the oscillation of the laser oscillation means, the first
and a means for controlling the second spectroscopic means to a state before the oscillation of the laser oscillation means, and during laser oscillation, the laser whose wavelength is selected by the two spectroscopic means of the first and second spectroscopic means is provided.・The wavelength and output of the laser beam are stabilized by extracting a part of the beam and controlling each spectroscopic means based on the analysis results of this laser beam, and after the laser oscillation is stopped, the thermal time constant unique to the spectroscopic means is Accordingly, it is an object of the present invention to provide a laser wavelength stabilizing device that controls a spectroscopic means so that it settles into a steady state when the laser is not oscillating.

[Operation] In the above means, the laser wavelength stabilizing device of the present invention performs wavelength stabilization by analyzing a part of the laser beam and controlling the spectroscopic means during laser oscillation, and after the laser oscillation is stopped, the laser wavelength stabilization device performs wavelength stabilization by controlling the spectroscopic means. The spectroscopic means is predictively controlled based on the time constant of , and the steady state during oscillation stop, so that when the laser is started to oscillate again, it oscillates at a predetermined wavelength.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a laser wavelength stabilizing device according to an embodiment of the present invention, and FIG. 2 is a schematic configuration diagram of a wavelength monitoring mechanism applied to the configuration of FIG. 1.

In each figure, (7) is the wavelength monitoring mechanism for monitoring the wavelength from the spectroscopy of the laser beam (6), (8) is the control mechanism, and (9) is the wavelength monitoring mechanism for monitoring the output from the spectroscopy of the laser beam (6). (10) is a servo mechanism that controls the fine adjustment etalon (5) based on the output of the control mechanism (8); (11) is a servo mechanism that controls the coarse adjustment etalon (4); (12) is the wavelength monitor mechanism (7)
The integrator (13) has the function of weakening or diffusing the spectrum of the laser beam (6), and the integrator (13) generates interference fringes depending on the incident angle of the light from the integrator (12), and combines the interference fringes. A Fabry-Perot etalon is formed on the image sensor (15) via the image lens (14), (16) is an image processing unit for analyzing interference fringes on the image sensor (15), and (17) is a servo mechanism ( (39) time-sharing control means for time-sharing controlling the operation signal given to 11);
(40) is an etalon state measuring means for determining the state of the rough adjustment etalon (4) by Δ1, and (40) is an etalon state measuring means for measuring the state of the fine adjustment etalon (5).

The operation of the above configuration will now be described.

By arranging a total reflection mirror (2) and a partial reflection mirror (3) at both ends of a laser medium (1), an optical resonator is constructed in the same manner as the configuration shown in FIG. 5, and a laser beam (6) is generated. By arranging a rough adjustment etalon (4) and a fine adjustment etalon (5) in the optical path of the optical resonator, an arbitrary wavelength λ within a range where the oscillation wavelength width is narrow and a gain is present can be set. laser beam (6) can be obtained. In the laser oscillator as described above, the laser beam (
6) Stabilize and control the output wavelength. Note that such a laser oscillator repeats oscillation and stopping of the laser, but different control methods are adopted when the laser is oscillating and when the laser is stopping.

First, a control method during laser oscillation will be described, and the control in this case consists of controlling the fine adjustment etalon (5) and controlling the laser output of the laser medium (1).

The control mechanism of the fine tuning etalon (5) directs the negative portion of the laser beam (6) to the wavelength monitoring mechanism (7), as shown in FIG. The wavelength monitor mechanism (7) is, for example, a literature magazine rlEEE Journal Quantum.
Electronics QE-14 ('78)
17J, it is sufficient to have a spectroscopy function using an etalon, a prism, a grating Fizeau interferometer, etc., but in this example, a Fabry-Perot etalon (13) and an image sensor (15) are used. An example of a configuration using . The wavelength monitor mechanism (7) is an integrator (12) that weakens or diffuses the laser beam.
, Fabry-Perot etalon (13), and imaging lens (1)
4), and has an optical system consisting of an integrator (1).
Of the divergent components generated in step 2), only the component having a specific incident angle θ passes through the Fabry-Perot etalon (13) and reaches the imaging lens (14). Here, the imaging lens (1
If the focal length of 4) is f, then the light having a component of θ converges at a focal position fθ away from the axis of the imaging lens (14), forming circular interference fringes. Therefore, by observing the position at which the light gathers using the image sensor (15), θ can be determined, and λ can be calculated from the equation for the transmission wavelength of the etalon shown above.

Incidentally, the intensity distribution of light on the imaging cord (15) is as shown in the characteristic diagram of FIG. In the figure, the vertical axis shows the output, and the horizontal axis shows the distance X from the center of the interference fringes. The winter mountains in the figure correspond to the differences in the order m of the etalon. The interval between winter mountains is called a free spectral range, and the wavelength can be uniquely determined within this range. Furthermore, since the free spectral range can be determined by designing the etalon, it is designed to be wider than the expected wavelength shift.

Furthermore, since winter mountains have a light intensity distribution corresponding to the wavelength distribution of the laser beam, an image processing unit (16) is required to process this and calculate θ. Furthermore, the current wavelength λ is calculated here, and the coarse adjustment etalon (4) and fine adjustment etalon (5) are controlled through the servo mechanism (10) and servo mechanism (11) to adjust the wavelength of the laser oscillator. conduct.

(A) of FIG. 4(a) is a flowchart showing an outline of a method for stabilizing the laser wavelength applied to the configuration of FIG. 1;
This shows an example in which the oscillation wavelength is controlled by finding the position where the spatial light intensity distribution of the laser beam is maximum.

In the figure, the Fabry-Perot etalon (13) converts the laser beam (6) into a spectrometer in step 818, and the one-dimensional light intensity distribution is measured by the image processing unit (16) in step S19. In step S20, this measurement data is subjected to image processing such as smoothing and removing noise, and in step S21, the position X showing the maximum intensity is determined, and then in step S
22, the specified position coordinate X for the specified wavelength. and if they are different, then X > X D x x x.

In step S23, the fine adjustment etalon (5) is controlled through the servo mechanism (10) to change the center wavelength λl112 of the etalon's transmission range, and the process returns to step 318 and repeats this operation until xmxo is reached. As described above, the oscillation wavelength of the laser can be kept constant by adjusting the fine adjustment etalon (5).

Next, the control mechanism of the rough adjustment etalon (4) will be explained. In FIG. 1, a portion of the laser beam (6) is directed to a power monitoring mechanism (9). The power monitor mechanism (9) consists of a part that measures the laser output and a part that records the obtained laser output, and this laser output value is taken into the time division control means (17) and the current laser medium (1 ) from the applied voltage value supplied to the laser medium (1) and the rough adjustment etalon (4).
The voltage applied to the laser medium (1) and the coarse adjustment etalon (4) are controlled in a time-sharing manner, thereby adjusting the laser output to be constant.

4(a) and 4(B) are flowcharts for explaining the outline of the laser output stabilization method applied to the configuration of FIG. 1.

As shown in the figure, first, in step S24, the laser output is measured by the power monitor mechanism (9), and in step S25, this measured output is averaged N times by the time-sharing control means (17), and the current Find the laser output value PN. Next, the laser output value P specified in step 826. (can be set externally) and calculate the absolute value 1ΔP1 of the difference between
Tolerance value P of variation between 1 value and preset laser output
(which can be set externally) is compared in step S27, and ΔpH
>p, in step 828 the voltage applied to the laser medium (1) is controlled or the coarse adjustment etalon (4
) should be controlled. First, the laser medium (
When controlling the applied voltage for 1), step S
In Step 29, the control amount of the applied voltage is determined from 1ΔP, and then in Step S30, it is determined whether to increase or decrease the applied voltage depending on the polarity of ΔP-P N Po. Thereafter, in step S31, the voltage applied to the laser medium (1) is controlled through the time division control means (17).

In addition, when adjusting the rough adjustment etalon (4), the coarse adjustment etalon (4) is adjusted from the value of IΔP1 in step S32.
, and then in step S33, ΔP "" P
Etalon for coarse adjustment (4) depending on the polarity of N P o
In step S3, it is determined which direction to control the
4, the coarse adjustment etalon (
4) Adjust. Note that if IΔPI≦Po, oscillation continues as is. By continuing such control while the laser is oscillating, the laser output can be controlled to be constant.

By the way, the two etalons, the rough adjustment etalon (4) and the fine adjustment etalon (5), may be controlled at the same time, but for example, if the center wavelength of the fine adjustment etalon (5) is moved too much, the laser output may decrease. It may fluctuate, and if control is performed in a chaotic manner, there is a possibility that the fluctuation of the output will become larger.

Therefore, in order to monitor both control states, the control mechanism (8
), and in the first part of the flowchart of FIG. 4(a), it is selected whether to perform control (A) or (B). Incidentally, in this embodiment, priority is given to control on the (B) side immediately after the start of laser oscillation, and priority is given to control on the (A) side after the operation has stabilized to some extent.

Next, a method of controlling the coarse adjustment etalon (4) and the fine adjustment etalon (5) after the laser oscillation is stopped will be explained. After the laser oscillation stops, the control mechanism (8) and the time division control means (1
The rough adjustment etalon (4) and the fine adjustment etalon (5) are arranged so that A(t)-A + (A-A) exp(-t/τ)
). Here, t is the elapsed time from the stop of oscillation, A is the quantity representing the state of the etalon, A is the value of A at t-Q, A(1) is the value of A at time t, A is t=■ -J6Ef is the value of A, τ is the time constant determined by the etalon. Specifically, the state quantity A of the etalon is determined by the servo mechanisms (10) and (11), and the coarse adjustment etalon (4),
The fine adjustment etalon (5) is mainly divided into the following three types depending on what is to be controlled.

A-n...(6)
A-d...(7)
Amcosθ...(8) Incidentally, when controlling the refractive index n of the etalon, equation (6) is
Equation (7) is expressed as (8
) formulas respectively correspond to the case where the angle θ of the etalon is controlled. In addition, A″′ and τ are the control mechanism (8)
This is the value stored in .

Figure 4(b) shows the coarse adjustment etalon (4) and the fine adjustment etalon (4) after the laser oscillation has stopped in the configuration shown in Figure 1.
5) is a flowchart for explaining an overview of control. As shown in the figure, in step S35, the value of A after the oscillation is stopped is stored. As the value of A, use the state constantly calculated in step S41 of flow (A) in FIG. 4(a) during oscillation, use the value immediately before the oscillation of IIA stops, or use the etalon state iA immediately after the oscillation stops. The value is measured and used by the etalon state measuring means (39) and the etalon state measuring means (40). Next, step S36
In step S37, the time after the oscillation stops is counted, and in step S37 (
A (t) is calculated according to the formula 5), and in step 838, the servo mechanism (10) and the sabot mechanism (11) are driven to adjust the coarse adjustment etalon (4) and the fine adjustment etalon (5).

In the above embodiment, the wavelength monitor mechanism (7) and the power
Although the monitor mechanism (9) was provided separately, the wavelength monitor mechanism (
The image processing unit (16) in 7) obtains a light intensity distribution as shown in Figure 3, so if it is operated for a long time without any control, the wavelength shift and output intensity change will occur as shown by the broken line. Therefore, if the intensity change of the peak measured by the image processing unit (16) is measured, the power monitor mechanism (
9) It is possible to monitor the laser output without separately providing it.

In addition, in the above embodiment, a configuration in which a Fabry-Perot etalon (13) is used in the wavelength monitor mechanism (7) is exemplified;
Any spectroscopic element such as a prism or a grating Fizeau interferometer may be used, and the same effect can be obtained by measuring the intensity distribution of the separated light.

In addition, in the above embodiment, the light intensity distribution of the laser beam separated by the wavelength monitor mechanism (7) is image-processed by the image processing unit (16) to determine the wavelength shift, and the fine adjustment etalon (5)
Although the configuration for driving the light intensity distribution has been exemplified, any configuration may be used as long as the wavelength distribution can be measured without image processing. For example, an optical sensor is placed at the position x""xo in Fig. 3, and the fine adjustment etalon (5) is changed from the optimum state, and the change in light intensity at the position X-Xo at that time is evaluated. A possible method is to predict the direction of the optimum state of the fine adjustment etalon (5) and control the fine adjustment etalon (5).

[Effects of the Invention] As described above, according to the present invention, during laser oscillation, wavelength stabilization is achieved by controlling one of the two etalons based on the spectral results of the laser beam. , the output is stabilized by controlling the applied voltage supplied to the laser medium and the other etalon in a time-sharing manner based on the laser output, and on the other hand, after the laser oscillation stops, these are predictively controlled according to the characteristics of the etalon. By doing this, the laser wavelength can be stabilized immediately after re-oscillation, which has the effect of greatly increasing the time that the laser can be used effectively for wavelength-stabilized lasers that repeatedly oscillate and stop, and for high-output lasers. There is.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a laser wavelength stabilizing device according to an embodiment of the present invention, FIG. 2 is a schematic configuration diagram of a wavelength monitoring mechanism applied to the configuration of FIG. 1, and FIG. Characteristic diagrams of the light intensity distribution of interference fringes on the imaging probe, FIGS. 4(a) and (b)
) is a flowchart for explaining the outline of the operation of the configuration shown in FIG. 1, FIG. 5 is a schematic configuration diagram of a well-known narrowband laser oscillator, and FIGS. Characteristic diagram explaining the principle of the method of narrowing the wavelength to determine the wavelength, No. 7
Figures (a) to (c) are explanatory diagrams of the wavelength shift of the etalon due to the stop of laser oscillation. Figures 8 (a) to (C) are the causes of output changes due to the difference in wavelength shift of the two etalons. FIG. In the figure, (1) is a laser medium, (2) is a total reflection mirror,
(3) is a partial reflector, (4) is a rough adjustment etalon, and (5
) is the etalon for fine adjustment, (6) is the laser beam, (7
) is the wavelength monitor mechanism, (8) is the control mechanism, (9) is the power monitor mechanism, (10) and (11) are the servo mechanism, (
17) is a time division control means, and (39) and (40) are etalon state measuring means. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Agent Patent Attorney Masuo Oiwa (2 others) Shishiri I OX Sosan Ken J Kien I (Ki o YyoR Procedural amendment (voluntary) 5. Detailed explanation of the invention in the specification to be amended. 6. Contents of the amendment 2. Name of the invention Laser wavelength stabilization device 3. Relationship with the person making the amendment Patent applicant address 2-3 Sara-chome, Marunouchi, Chiyoda-ku, Tokyo Name (601) Mitsubishi Electric Corporation Representative Moriya Shiki 4, substitute

Claims (1)

[Claims] Laser oscillation means that emits a laser beam with a variable oscillation wavelength using a first spectroscopic means and a second spectroscopic means, and a wavelength that extracts a part of the laser beam emitted from the laser oscillation means and measures the oscillation wavelength. monitoring means; first control means for controlling the first spectroscopic means based on the output of the wavelength monitoring means to stabilize the wavelength of the laser oscillation means; and a part of the laser beam emitted from the laser oscillation means. a power monitor means for taking out and measuring the laser output; a voltage control means for controlling the voltage applied to the laser medium of the laser oscillation means; a second control means for controlling the second spectroscopy means; an output stabilizing means for stabilizing the output of the laser oscillation means by time-sharingly operating the voltage control means and the second control means based on the output of the laser oscillation means; After measuring the amount of thermal strain in the spectroscopic means and the second spectroscopic means and stopping the oscillation of the laser oscillating means, the first spectroscopic means and the second spectroscopic means are activated to oscillate the laser oscillating means based on the thermal time constant specific to the spectroscopic means. A laser wavelength stabilizing device characterized by comprising means for controlling to a previous state.