JP2001337356A - Light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate efficiently the light of a wavelength of 200 nm or shorter with a simple constitution. SOLUTION: The light of a single wavelength within the wavelength range from IR region up to visible region generated by a laser generating section is subjected to wavelength conversion to UV light of a wavelength of 200 nm or shorter by a wavelength conversion section 16. The UV light of the prescribed wavelength of <=200 nm is efficiently generated by sum frequency generation using a CBO crystal 46 in the final step of the wavelength conversion as the wavelength conversion section 16 or the intermediate step which is not the final step of the wavelength conversion but generates the UV light of a wavelength of 200 nm or shorter. As a result, the UV light of the wavelength of desired 200 nm or shorter is efficiently generated by a simple constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source device,
More specifically, the present invention relates to a light source device that generates ultraviolet light having a wavelength of 200 nm or less.

[0002]

2. Description of the Related Art Conventionally, many light sources for generating short-wavelength light have been developed for inspecting the fine structure of an object, finely processing the object, and treating vision correction. The development direction of such a short wavelength light source is mainly as follows.
They are roughly classified into species. One is the development of an excimer laser light source in which the laser oscillation wavelength itself is a short wavelength, and the other is the development of a short wavelength light source utilizing harmonic generation of an infrared or visible light laser.

Of these, KrF
A light source device using an excimer laser (wavelength: 248 nm) has been developed.
Development of a light source device using an excimer laser (wavelength 193 nm) or the like has been advanced. However, these excimer lasers have disadvantages as a light source device, such as being large in size, and using a toxic fluorine gas, so that the maintenance of the laser is complicated and the cost is high.

Therefore, utilizing the nonlinear optical effect of a nonlinear optical crystal, which is a method of shortening the wavelength along the latter direction,
Attention has been focused on a method of converting long-wavelength light (infrared light or visible light) into shorter-wavelength ultraviolet light. As a light source device using such a method, for example, International Publication WO99 /
No. 46835 (hereinafter simply referred to as “conventional example”).

[0005]

In the method of shortening the wavelength using the above-described nonlinear optical crystal, the efficiency of generating the short-wavelength light is determined by the efficiency of generating the nonlinear optical effect in the nonlinear optical crystal used. Then, it is difficult to say that the generation efficiency of the nonlinear optical effect of the available nonlinear optical crystal is high. In particular, the types of nonlinear optical crystals that can be used to generate ultraviolet light having a wavelength of 200 nm or less that can be generated by the above-described ArF excimer laser are limited, and the generation efficiency of the nonlinear optical effect by these nonlinear optical crystals is: It tends to be smaller than light having a wavelength of 200 nm or more.

For example, in the above conventional example, about 193 nm
In order to generate light having a wavelength of about 1544 nm, light having a wavelength of about 1544 nm is used as a fundamental wave, and LiB ₃ O ₅ (LB) is used as a nonlinear optical crystal for generating a sum frequency of the fundamental wave and its seventh harmonic.
It is disclosed to use O) crystals or CsLiB ₆ O ₁₀ (CLBO) crystals. However, even if these types of nonlinear optical crystals were used, it was difficult to say that light having a wavelength of about 193 nm, which is the eighth harmonic of the fundamental wave, could be generated with sufficient efficiency.

For this reason, a technique for improving the generation efficiency of short-wavelength light has been long-awaited, and research and development therefor are continuously being conducted.

The present invention has been made under the above circumstances, and an object of the present invention is to provide a light source device capable of efficiently generating ultraviolet light having a wavelength of 200 nm or less with a simple configuration. It is in.

[0009]

According to the knowledge obtained by the present inventors over many years of research, CsB ₃ O ₅ (CBO) crystal, which has been known as one of the nonlinear optical crystals, has been developed.
It has been found that the generation efficiency of light having a wavelength of 200 nm or less is higher than that of a conventionally used LBO crystal or CLBO crystal in generating a sum frequency. The present invention has been made based on such findings.

That is, the light source device of the present invention comprises: a laser light generator (12) having a single-wavelength oscillation laser (12A) for generating light of a single wavelength within a wavelength range from an infrared region to a visible region; A wavelength conversion unit (16) for converting incident light having the same wavelength as the laser light generated by the laser light generation unit into ultraviolet light having a wavelength of 200 nm or less, wherein the wavelength conversion unit performs A light source device comprising a CBO crystal (46) that generates ultraviolet light having a wavelength of 200 nm or less.

According to this, the light of a single wavelength within the wavelength range from the infrared region to the visible region generated by the laser light generator is generated.
The wavelength conversion unit converts the wavelength to ultraviolet light having a wavelength of 200 nm or less, but at the final stage of wavelength conversion as a wavelength conversion unit, or not at the final stage of wavelength conversion, but at an intermediate stage that generates ultraviolet light of a wavelength of 200 nm or less. , And a CBO crystal is used to generate ultraviolet light of a predetermined wavelength of 200 nm or less by sum frequency generation. Therefore, it is possible to efficiently generate ultraviolet light having a predetermined wavelength of 200 nm or less, so that it is possible to efficiently generate ultraviolet light having a desired wavelength of 200 nm or less with a simple configuration as output light of the wavelength conversion unit. it can.

In the light source device according to the present invention, for example, the wavelength conversion section may use the incident light as a fundamental wave to generate a sum frequency of the fundamental wave and a seventh harmonic of the fundamental wave by the CBO crystal. Accordingly, it is possible to have a configuration in which ultraviolet light having a frequency eight times higher than the fundamental wave is generated.

Here, the single-wavelength oscillation laser includes:
A laser beam having an oscillation wavelength in the range of 544 μm to 1.552 μm is generated.
It can be configured to generate ultraviolet light in the range of 94 nm. In such a case, it is possible to efficiently generate ultraviolet light in the range of 193 nm to 194 nm, which is the same wavelength as that of the ArF excimer laser.

Further, the light source device of the present invention may further include an optical amplifier (14) for amplifying the laser light generated by the laser light generator and emitting the amplified laser light toward the wavelength converter. . In such a case, after the optical amplifier amplifies the laser light generated by the laser light generator, the amplified laser light with high luminance is supplied to the wavelength converter. Therefore, it is possible to efficiently generate high-intensity ultraviolet light having a wavelength of 200 nm or less.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a block diagram showing a schematic configuration of a light source device 10 according to an embodiment of the present invention. The light source device 10 is a harmonic generation device that outputs ultraviolet pulse light having a wavelength of 193 nm (substantially the same wavelength as ArF excimer laser light).

The light source device 10, as shown in FIG.
Light source unit 10A, laser controller 10B, light amount controller 1
0C, the light source control device 11, and the like.

The light source section 10A includes a pulse light generation section 12, a light amplification section 14, a wavelength conversion section 1 as a laser light generation section.
6 and a beam monitor mechanism 18.

The pulse light generator 12 is provided with the laser light source 1.
2A, an optical coupler BS1, an optical isolator 12B, an electro-optical modulator (hereinafter, referred to as “EOM”) 12C, and the like. The elements between the laser light source 12A and the wavelength converter 16 are optically connected by an optical fiber or the like.

As the laser light source 12A, here, a single wavelength oscillation laser, for example, an oscillation wavelength of 1.544
μm, continuous wave output (hereinafter referred to as “CW output”) InG
aAsP and DFB semiconductor lasers are used. Hereinafter, the laser light source 12A is also referred to as “DFB semiconductor laser 12A” as appropriate.

The DFB semiconductor laser 12A is usually provided on a heat sink, and these are housed in a housing. In this embodiment, the DFB semiconductor laser 1
A temperature controller (for example, a Peltier element) is provided on a heat sink attached to 2A, and the oscillation wavelength can be controlled (adjusted) by controlling the temperature of the laser controller 10B.

The optical coupler BS1 has a transmittance of about 97%. Therefore, DFB
The laser light from the semiconductor laser 12A is supplied to the optical coupler BS.
The light is branched into two by 1, and about 97% of the light is directed toward the next-stage optical isolator 12C, and the remaining about 3% is incident on the beam monitor mechanism 18.

The beam monitor mechanism 18 includes an energy monitor (not shown) composed of a photoelectric conversion element such as a photodiode. The output of this energy monitor is supplied to the light source control device 11 via the laser control device 10B. The light source control device 11 detects the energy power of the laser light based on the output of the energy monitor, and controls the laser control device 10B. Control the amount of laser light oscillated by the DFB semiconductor laser 12A via the
For example, the FB semiconductor laser 12A is turned off.

The optical isolator 12B passes only the light in the direction from the optical coupler BS1 to the EOM 12C, and blocks the light in the opposite direction. The optical isolator 12B prevents a change in the oscillation mode of the DFB semiconductor laser 12A and the generation of noise due to the reflected light (return light).

The EOM 12C is an optical isolator 12
This is for converting the laser light (CW light (continuous light)) that has passed through B into pulsed light. As EOM12C,
An electro-optic modulator (for example, a two-electrode modulator) having an electrode structure that has been subjected to chirp correction is used so that the wavelength spread of the semiconductor laser output due to chirp due to a change in refractive index over time is reduced. The EOM 12C outputs a pulse light modulated in synchronization with a voltage pulse applied from the light amount control device 10C. For example, D
The laser light oscillated by the FB semiconductor laser 12A is modulated into a pulse light having, for example, a pulse width of 1 ns and a repetition frequency of 100 kHz (a pulse period of about 10 μs). The repetition frequency is determined by an ASE (Amplified Spontaneous Emissio) in a fiber amplifier 22 (see FIG. 2) described later.
(n, spontaneous emission light) A value that can suppress the influence of noise is selected.

The voltage applied to the EOM 12C and the DFB
It is desirable that the output light be pulsed in combination with the control of the supply current to the semiconductor laser 12A. In such a case, the extinction ratio can be improved. This makes it possible to easily generate a pulse light with a narrow pulse width while improving the extinction ratio as compared with the case where only the EOM 12C is used. The stop and the like can be controlled more easily. Also, an acousto-optic light modulator (AOM) can be used instead of the EOM 12C.

The optical amplifier 14 amplifies the pulse light from the EOM 12C, and as shown in FIG.
It is configured to include an optical branching unit 21 that periodically distributes the pulsed light from the OM 12C in time order and branches (for example, 128 branches), and a plurality of fiber amplifiers 22.

As shown in FIG.
2 combines the output light of the EOM 12C and the pump light with the amplification fiber 23, the pumping semiconductor lasers 24 ₁ and 24 ₂ for generating the pump light, and supplies the combined light thus obtained to the amplification fiber 23. Wavelength Division Multiplexer (Wave
length division multiplexer (WDM) 25 ₁ , 25 ₂ . Here, the pumping semiconductor laser 24 ₁ and W
DM25 ₁ is used for forward excitation, while the pumping semiconductor laser 24 ₂ and WDM25 ₂ are used in backward pumping. As a result, the linearity of the optical amplification factor with respect to the input light intensity is maintained, and the optical amplification factor is improved.

The amplification fiber 23 is made of silica glass as a main material, has a core and a clad, and is an optical fiber in which the core is doped with Er or two kinds of ions of Er and Yb at a high density. . The amplification fiber 23
Can adopt a double clad fiber structure having a double clad structure.

The fiber amplifier 2 configured as described above
2, the pump light generated by the pumping semiconductor lasers 24 ₁ and 24 ₂ is supplied to the amplifying fiber 23 by the WDMs 25 ₁ and 2 2.
5 ₂ while being fed through, when the pulse light through the WDM25 ₁ travels through the core of the amplifier fiber 23 is incident, stimulated emission occurs, the pulse light is amplified. In such optical amplification, since the amplification fiber 23 has a high amplification rate, high-intensity pulsed light having high unity of wavelength is output. For this reason, narrow-band light can be obtained efficiently.

The pumping semiconductor lasers 24 ₁ and 24 ₂ are:
Light having a wavelength (for example, 980 nm) shorter than the oscillation wavelength of the DFB semiconductor laser 12A is generated as pump light. This pump light is supplied to the amplification fiber 23 via the WDMs 25 ₁ and 25 ₂ , thereby exciting Er and generating a so-called inverted population of energy levels. The semiconductor lasers for excitation 24 ₁ and 24 ₂ are controlled by a light quantity control device 10C.

In this embodiment, in order to suppress the difference in gain between the fiber amplifiers 22, the fiber amplifiers 22 are used.
, A part of the output is branched and photoelectrically converted by the photoelectric conversion elements 26 provided at the respective branch ends. The output signals of these photoelectric conversion elements 26 are supplied to the light quantity control device 10C.

[0033] In the light quantity control device 10C, as such (i.e. to balance), the feedback control of the drive current of each pumping semiconductor laser 24 _1, 24 ₂ optical output becomes constant from the fiber amplifier 22 Has become.

The wavelength conversion section 16 includes a plurality of nonlinear optical crystals, and the amplified pulse light (wavelength 1.544)
(μm light) is converted into an eighth harmonic thereof to generate pulsed ultraviolet light having substantially the same output wavelength (193 nm) as the ArF excimer laser.

FIG. 3 shows an example of the configuration of the wavelength converter 16. Here, based on this figure, the wavelength converter 1
A specific example 6 will be described. In FIG. 3, a fundamental wave having a wavelength of 1.544 μm emitted from the optical amplification unit 14 is
The wavelength is converted to an eighth harmonic (harmonic) using a nonlinear optical crystal, and the wavelength is substantially the same as that of the ArF excimer laser 193.
1 shows a configuration example for generating ultraviolet light of nm.

In the wavelength converter 16 shown in FIG. 3, the fundamental wave (wavelength 1.544 μm) → the second harmonic wave (wavelength 772 nm) → the third harmonic wave (wavelength 515 nm) → the fourth harmonic wave (wavelength 386 nm) → the seventh harmonic wave (wavelength 221 nm) → the eighth harmonic (wavelength 193 nm) in this order.

More specifically, a fundamental wave having a wavelength of 1.544 μm (frequency ω) output from the optical amplifier 14 enters the first-stage nonlinear optical crystal 31. When the fundamental wave passes through the nonlinear optical crystal 31, a second harmonic is generated, which is twice the frequency ω of the fundamental wave, that is, a double wave of a frequency 2ω (wavelength 772 nm).

As the first-stage nonlinear optical crystal 31,
An LBO crystal is used, and a method of adjusting the temperature of the LBO crystal for phase matching for wavelength conversion of a fundamental wave to a second harmonic is used.
CPM (Non-Critical Phase Matching) is used. The NCPM does not cause a walk-off between the fundamental wave and the second harmonic (second harmonic) in the nonlinear optical crystal, so that conversion to the second harmonic wave can be performed with high efficiency and is generated. 2
The harmonic wave is advantageous because the beam is not deformed by the walk-off.

The fundamental wave transmitted without wavelength conversion by the nonlinear optical crystal 31 and the second harmonic generated by the wavelength conversion are given a half wavelength and a one wavelength delay by the next-stage wave plate 32, respectively. Only the fundamental wave rotates its polarization direction by 90 degrees, and enters the second-stage nonlinear optical crystal 34 after passing through the condenser lens 33. An LBO crystal is used as the second-stage nonlinear optical crystal 34, and the LBO crystal has a different temperature from the first-stage nonlinear optical crystal (LBO crystal) 31.
Used in M. In this nonlinear optical crystal 34, a third harmonic (wavelength: 515 nm) is generated from the second harmonic generated in the first-stage nonlinear optical crystal 31 and the fundamental wave transmitted through the nonlinear optical crystal 31 without wavelength conversion. Get)

Next, the third harmonic obtained by the nonlinear optical crystal 34 and the fundamental wave and the second harmonic transmitted through the nonlinear optical crystal 34 without wavelength conversion are separated by the dichroic mirror 35, The third harmonic reflected by the light passes through the condenser lens 38 and the dichroic mirror 41 and
The light enters the non-linear optical crystal 43 of the stage. On the other hand, the fundamental wave and the second harmonic transmitted through the dichroic mirror 35 are
The light enters the third-stage nonlinear optical crystal 37 through the condenser lens 36.

The third-stage nonlinear optical crystal 37 is LB
O crystal is used, and its LB is
While transmitting through the O crystal, the second harmonic is converted into a fourth harmonic (wavelength 386 nm) by the second harmonic generation in the LBO crystal. The fourth harmonic obtained by the nonlinear optical crystal 37 and the fundamental wave transmitted therethrough are separated by the dichroic mirror 39, and the fundamental wave transmitted therethrough passes through the condenser lens 42 and is reflected by the dichroic mirror 44. Been 5
The light enters the non-linear optical crystal 46 of the stage. On the other hand, the fourth harmonic reflected by the dichroic mirror 39 reaches the dichroic mirror 41 through the condenser lens 40, where it is coaxially synthesized with the third harmonic reflected by the dichroic mirror 35, and is combined in four stages. The light enters the nonlinear optical crystal 43 of the eye.

As the fourth-stage nonlinear optical crystal 43, β
-BaB ₂ O ₄ (BBO) crystal is used, to obtain a 7 harmonic (wavelength 221 nm) by the sum frequency generation and a triple wave and fourth harmonic. The seventh harmonic obtained by the non-linear optical crystal 43 passes through the condenser lens 45 and is also dichroic mirror 44
Then, the light is synthesized coaxially with the fundamental wave transmitted through the dichroic mirror 39 and enters the fifth-stage nonlinear optical crystal 46.

As the fifth-stage nonlinear optical crystal 46, CBO
A crystal is used, and an eighth harmonic (wavelength: 193 nm) is obtained by generating a sum frequency from the fundamental wave and the seventh harmonic.

The CBO crystal used as the nonlinear optical crystal 46 has a fundamental wave (wavelength of 1544 nm) and a seventh harmonic (a wavelength of 1544 nm) as compared with the conventionally used nonlinear optical crystals CLBO, BBO and LBO crystals. Wavelength 221
nm) to 8th harmonic (wavelength 193 nm) by sum frequency generation
Are different from each other as shown in FIG. Here, the suitability of the generation of the eighth harmonic (wavelength: 193 nm) by the above-mentioned sum frequency generation will be examined with reference to the optical characteristics of various crystals shown in FIG.

First, the cutoff wavelength (λ _CUT-OFF ) will be examined. In generating the sum frequency, it is necessary that the cut-off wavelength of the optical crystal used is shorter than the wavelength of the generated sum frequency, and it is preferable that the cutoff wavelength be shorter than the wavelength of the generated sum frequency. From this point of view, LBO crystals are most advantageous, followed by CBO crystals. On the other hand, the cut-off wavelength of the BBO crystal is shorter than the wavelength of the eighth harmonic, which is the generated sum frequency, but the difference is very small, which is disadvantageous for the generation of the eighth harmonic.

Next, the effective piezoelectric d coefficient (d _eff ) will be discussed. If the effect of the cutoff wavelength is not considered, the greater the square of the effective piezoelectric d coefficient, the higher the generation efficiency in sum frequency generation. From this perspective, the use of BBO crystals is considered to be most advantageous, followed by CBO crystals. On the other hand, it can be seen that the LBO crystal has an extremely small effective piezoelectric d coefficient as compared with others, and is disadvantageous for the generation of the eighth harmonic.

Considering the above two points related to the sum frequency generation efficiency, it is considered that the CBO crystal is the most advantageous for the generation of the eighth harmonic, and the CLBO crystal is second. On the other hand, the BBO crystal and the LBO crystal
It is considered disadvantageous for generation of harmonics.

The allowable adjustment angle of the phase matching angle (the deviation angle from the phase matching angle at which the sum frequency generation efficiency becomes １ ／ as compared with the case where the phase matching angle is accurately set) is CB.
O crystals are larger than CLBO crystals. Therefore,
From the viewpoint of equipment assembly, the CBO crystal is CLB
Advantages over O crystals.

The Walk-off angle (ρ) of the CBO crystal is smaller than that of the CLBO crystal. Therefore, from this viewpoint, the CBO crystal is more advantageous than the CLBO crystal.

Further, the CBO crystal has a lower deliquescence than the CLBO crystal, and is superior to the CLBO crystal in terms of installation environment resistance.

Therefore, the CBO crystal has an overall advantage over the conventional nonlinear optical crystal shown in FIG. 4 with respect to the efficient generation of the eighth harmonic described above. It can be said that. For this reason, the wavelength conversion unit 16 of the present embodiment can perform wavelength conversion very efficiently.

As described above, according to the light source device 10 according to the present embodiment, the light of the same wavelength as the light of the single wavelength within the infrared wavelength range generated by the pulsed light generator 12 is
Ultraviolet light having a wavelength of 200 nm or less is generated by using a CBO crystal as the final stage of wavelength conversion and generating a sum frequency. Therefore, ultraviolet light having a wavelength of 200 nm or less can be efficiently generated.

The DFB included in the pulse light generator 12
The wavelength converter 16 uses the light having the same wavelength as the 1544 nm laser light generated by the semiconductor laser 12A as a fundamental wave.
Generates the sum frequency of the fundamental wave and the seventh harmonic of the fundamental wave by CB
Since the O-crystal is used, ultraviolet light having substantially the same wavelength as that of the ArF excimer laser can be efficiently generated.

Further, the optical amplification unit 14 is configured to
Since the laser light generated by 2 is amplified and supplied to the wavelength converter 16, the amplified laser light with high luminance is supplied to the wavelength converter. Therefore, it is possible to efficiently generate high-intensity ultraviolet light having a wavelength of 200 nm or less.

The configuration of the wavelength conversion section in the above embodiment is merely an example, and it goes without saying that the configuration of the wavelength conversion section of the present invention, the material of the nonlinear optical crystal, the output wavelength, and the like are not limited thereto. For example, a fundamental wave having a wavelength of 1.57 μm emitted from the optical amplifying unit 14 is subjected to harmonic generation of a tenth harmonic using a non-linear optical crystal to generate 157 nm ultraviolet light having the same wavelength as the F ₂ laser. At this time, it is also possible to generate an eighth harmonic by sum frequency generation using a CBO crystal at an intermediate stage of wavelength conversion.

The wavelength of ultraviolet light generated from the CBO crystal used in the final or intermediate stage of the wavelength conversion may be set arbitrarily, for example, with the cut-off wavelength (practical value) of the CBO crystal as the lower limit. Note that the ultraviolet light generated from the CBO crystal may be a harmonic other than the eighth harmonic,
The sum frequency generation in the crystal may be a combination other than the fundamental wave and the seventh harmonic.

In the above embodiment, the laser light source 1
2A is not limited to a semiconductor laser such as a DFB semiconductor laser, but is preferably, for example, an ytterbium (Yb) -doped fiber laser having an oscillation wavelength of about 990 nm, but is not limited thereto.

In the above embodiment, the Er-doped fiber is used as the amplification fiber. However, a Yb-doped fiber or another rare-earth element-doped fiber may be used.

The number of the fiber amplifiers 22 arranged in parallel in the optical amplifier 14 may be arbitrary, and if the number is determined according to the specifications required for the product to which the light source device according to the present invention is applied. Good. In particular, when high output is not required for the light source device, the fiber amplifier 22
And the configuration can be simplified. When simplifying to include only one fiber amplifier 22, the splitter 21 is not required.

The beam monitor mechanism 18 further includes a Fabry-Perot etalon (hereinafter, also referred to as an “etalon element”), and detects the intensity of light incident on the etalon element and transmitted therethrough. By performing signal processing on the detection result in the laser control device 10B, information on the optical characteristics of the incident light with respect to the etalon element (specifically, the central wavelength and the wavelength width (spectral half width) of the incident light, etc. are obtained). And, based on this information about the optical properties,
The laser control device 10B may perform the temperature control (and the current control) of the DFB semiconductor laser 12A by feedback control so that the center wavelength becomes a desired value (set wavelength).

The absolute wavelength of the oscillation wavelength of the DFB semiconductor laser 12A is calibrated using an absorption cell such as an acetylene isotope, and the output wavelength of the DFB semiconductor laser 12A is controlled based on the calibration result. You can also. Further, as the light for monitoring the wavelength of the laser light, the intermediate wave (the second harmonic, the third harmonic, the fourth harmonic, or the like) of the above-described wavelength converter 16 or the wavelength-converted light after the wavelength conversion, together with or instead of the fundamental wave When light is selected, an absorption cell in which absorption lines exist densely in a wavelength band such as an intermediate wave may be used. For example, when the third harmonic is selected as the light for monitoring the wavelength, the wavelength 503n
An iodine molecule having an absorption line densely in the vicinity of m to 530 nm may be used as an absorption cell, and an appropriate absorption line of the iodine molecule may be selected and its wavelength may be used as an absolute wavelength. Note that the absolute wavelength source is not limited to the absorption cell, and an absolute wavelength light source may be used.

The light source device of the present invention can be used for various devices. For example, as a light source device used in a laser treatment device that irradiates the cornea with laser light to perform ablation of the surface or ablation inside the incised cornea, correct curvature or unevenness of the cornea and perform treatment such as myopia and astigmatism. Can be used. Further, it can also be used as a light source of exposure light used in an exposure apparatus that transfers a fine pattern onto a substrate. Further, the light source device of the present invention can be used as a light source device in an optical inspection device or the like.

The light source device of the present invention can also be used for optical adjustment (optical axis alignment, etc.) of an optical system or for inspection. Further, in various devices having an excimer laser as a light source, the light source device of the present invention can be applied in place of the excimer laser.

[0064]

As described above in detail, according to the light source device of the present invention, the light of a single wavelength within the wavelength range from the infrared region to the visible region generated by the laser light generating portion is converted into the wavelength converting portion. Is converted into ultraviolet light having a wavelength of 200 nm or less,
In the final or intermediate stage of the wavelength conversion, a CBO crystal is used to generate a sum frequency to efficiently generate ultraviolet light having a predetermined wavelength of 200 nm or less. Therefore, the light source device of the present invention can efficiently generate ultraviolet light having a desired wavelength of 200 nm or less.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing a configuration of a light source device according to an embodiment of the present invention.

FIG. 2 is a diagram schematically illustrating a fiber amplifier and a peripheral portion thereof that constitute the optical amplification unit in FIG. 1 together with a part of a wavelength conversion unit.

FIG. 3 is a diagram illustrating a configuration of a wavelength conversion unit in FIG. 1;

FIG. 4 is a view showing optical characteristics of various crystals.

[Explanation of symbols]

Reference numeral 10: light source device, 12: pulse light generation unit (laser light generation unit), 12A: laser light source (single wavelength oscillation laser), 1
4 ... optical amplifying part, 16 ... wavelength converting part, 46 ... CBO crystal.

 ──────────────────────────────────────────────────続 き Continuing from the front page (71) Applicant 500244540 Masashi Yoshimura 2-10 Nobuhirocho, Fukuyama City, Hiroshima Prefecture (72) Inventor Soichi Yamato 3-2-3 Marunouchi, Chiyoda-ku, Tokyo Nikon Corporation (72 ) Inventor Tomoko Otsuki 3-2-3 Marunouchi, Chiyoda-ku, Tokyo Inside Nikon Corporation (72) Inventor Takatomo Sasaki 2-8-A9-310 Yamada Nishi 2-chome, Suita-shi, Osaka (72) Inventor Yusuke Mori Osaka 8-16-9, Ichiichi, Fukano-shi (72) Inventor Masashi Yoshimura 2-10 Nobuhirocho, Fukuyama-shi, Hiroshima F-term (reference) 2K002 AA07 AB12 CA02 GA04 GA05 HA19 HA20 5F072 AB09 AB13 HH07 KK05 KK12 KK30 PP07 QQ02 RR05 SS06 YY09

Claims (4)

[Claims] 1. A laser light generating section having a single-wavelength oscillation laser for generating light of a single wavelength within a wavelength range from an infrared region to a visible region, and the same laser light generated by the laser light generating portion. A wavelength conversion unit that converts the wavelength of incident light into ultraviolet light having a wavelength of 200 nm or less, wherein the wavelength conversion unit has a CBO crystal that generates ultraviolet light having a wavelength of 200 nm or less by sum frequency generation. Characteristic light source device. 2. The wavelength conversion section, using the incident light as a fundamental wave, performs a sum frequency generation of the fundamental wave and a seventh harmonic of the fundamental wave by the CBO crystal, so that the wavelength is eight times the fundamental wave. The light source device according to claim 1, wherein the light source generates harmonic ultraviolet light. 3. The single-wavelength oscillation laser according to claim 1, wherein
3. The light source device according to claim 2, wherein the light source device generates a laser beam having an oscillation wavelength in a range of μm to 1.552 μm, and the wavelength conversion unit generates an ultraviolet light in a range of 193 nm to 194 nm. 4. . 4. The apparatus according to claim 1, further comprising: an optical amplifier that amplifies the laser light generated by the laser light generator and emits the laser light toward the wavelength converter. The light source device according to claim 1.