JPH07318997A - Optical parametric oscillator - Google Patents

Abstract

PURPOSE:To provide an optical parametric oscillator to which a wavelength sepn. optical system consisting of an SRO resonator and a dichroic mirror is applicable and with which the light of a signal wavelength region over the greater part of visible light is obtainable with high output without exchange of the optical element of the mirror by restricting the light to be taken out to the wavelength region of signal light. CONSTITUTION:The SRO resonator of the optical parametric oscillator for oscillating the third higher harmonic wave of a YAG laser to exciting light p is composed of a BBO crystal 21 which is formed by subjecting the incident and exit end faces to antireflection coating for the light of the wavelength region of the signal light s and the exciting light p and a resonator rear mirror 22 and resonator output mirror 23 having optical characteristics to resonate and amplify the signal light s. The signal light s emitted from the resonator output mirror 23 by resonating and amplifying the signal light s with the SRO resonator is taken out by the wavelength sepn. sepn. optical system consisting of a dichroic mirror 24 for separating the exciting light and dichroic mirrors 26, 27 for separating signal idlers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical parametric oscillator.

[0002]

2. Description of the Related Art FIG. 5 shows an example of a conventional optical parametric oscillator excited by a third harmonic of a YAG laser. Reference numeral 1 is a BBO crystal (β-Ba) which is a nonlinear optical crystal.
B ₂ O ₄ crystal), 2 is a humidity controller having a hollow structure.

The humidity adjuster 2 has a hollow adjuster body 3 having openings at one end and the other end, a resonator rear mirror 4 airtightly held in an opening at one end of the adjuster body 3, and an adjuster body 3. Has a resonator output mirror 5 hermetically supported at the opening at the other end thereof, and is configured so that the inside thereof can be maintained at a predetermined low humidity.

The BBO crystal 1 is supported by a crystal angle adjuster 6 provided inside the humidity adjuster 2.

The crystal angle adjuster 6 is configured to set the angle of the BBO crystal 1 based on the angle command signal 8 output from the crystal angle command unit 7.

The resonator rear mirror 4 has a wavelength of 355.
When the excitation light p of nm is incident, the excitation light p passes through the resonator rear mirror 4 and is incident on the BBO crystal 1,
In the O crystal 1, a signal light s and an idler light i having a wavelength different from that of the excitation light p are generated based on the relationship of the following formula (1). 1 / λp = 1 / λs + 1 / λi (1) (λp: wavelength of pumping light p, λs: wavelength of signal light s,
λi: wavelength of idler light i)

Therefore, the resonator output mirror 5 is generated by the BBO crystal 1 and is generated by the resonator output mirror 5.
The signal light s and the idler light i resonated and amplified by the resonator rear mirror 4 and the remaining pumping light p not converted into the signal light s and the idler light i in the BBO crystal 1 are emitted.

That is, both the signal light s and the idler light i are generated and resonated by the BBO crystal 1, the resonator rear mirror 4 and the resonator output mirror 5.
RO resonator (Double Resonant Osc
illator) is configured.

The wavelength λs of the signal light s is about 410 to 700 nm by adjusting the angle of the BBO crystal 1.
, And the wavelength λi of the idler light i is B
By adjusting the angle of the BO crystal 1, about 730-25
It varies in the range of 00 nm.

Reference numeral 9 is an excitation light cutoff filter composed of an absorption type filter. The excitation light cutoff filter 9 absorbs the excitation light p emitted from the resonator output mirror 5 and outputs the signal light s and the idler light i. It has the property of transmitting light.

In the excitation light blocking filter 9, the absorbed excitation light p is converted into heat.

Reference numerals 10a, 10b and 10c are wavelength selection filters composed of absorption filters, and the wavelength selection filters 10a, 10b and 10c are used for the signal light s and the idler light i emitted from the excitation light blocking filter 9. It has a property of transmitting only light in a specific wavelength region (a part of the signal light s is transmitted in the filter 10a) and absorbing light in other wavelength regions.

The wavelength selection filters 10a, 10b, 1
At 0c, the idler light i or the signal light s to be absorbed is
Is converted to heat.

These wavelength selection filters 10a, 10
The transmission wavelength regions of b and 10c are different from each other.

Therefore, while adjusting the angle of the BBO crystal 1, the wavelength selection filter 10a,
By selecting 10b and 10c, the signal light s or the idler light i having a required wavelength can be selectively obtained.

The means for supplying the pumping light p to the optical parametric oscillator having the above-described configuration is a YAG laser oscillator 11, a YAG laser second harmonic generator 12, YA.
It is composed of a G laser third harmonic generator 13 and the like.

The YAG laser oscillator 11 oscillates a YAG laser fundamental wave (laser light having a wavelength of 1064 nm).

The YAG laser second harmonic generator 12 outputs the 1 / λ ₂ = 1 / λ ₁ + 1 / λ ₁ (2) (λ ₁ from the YAG laser fundamental wave oscillated by the YAG laser oscillator 11). : wavelength of the fundamental wave, lambda _2: BBO second by the relationship harmonic wavelengths) (second harmonic generation), as a second harmonic generation non-linear optical crystal for generating the YAG laser second harmonic having a wavelength of 532nm It has a crystal 14.

The YAG laser third harmonic generator 13 is the BBO crystal 1 of the YAG laser second harmonic generator 12 described above.
YAG laser second harmonic generated by No. 4 and Y remaining without being converted into YAG laser second harmonic by the BBO crystal.
From the AG laser fundamental wave, 1 / λ ₃ = 1 / λ ₁ + 1 / λ ₂ (3) (λ ₁ : fundamental wave wavelength, λ ₂ : second harmonic wavelength, λ ₃ :
Third wavelength for generating a YAG laser third harmonic having a wavelength of 355 nm according to the relationship (wavelength of third harmonic) (sum frequency generation).
It has a KD * P crystal 15 as a nonlinear optical crystal for generating harmonics.

The above YAG laser third harmonic generator 13
The YAG laser third harmonic generated by the KD * P crystal 15 and the YAG laser fundamental wave and the YAG laser second harmonic remaining without being converted into the YAG laser third harmonic by the KD * P crystal 15 are dichroic mirrors. It is designed to be incident on 16.

This dichroic mirror 16 has a wavelength of 3
The YAG laser fundamental wave and YA, which have the optical characteristics of reflecting the third harmonic of the 55 nm YAG laser and transmitting other wavelength components, are transmitted through the dichroic mirror 16.
The G laser second harmonic is absorbed and shielded by the beam damper 17.

Further, the third harmonic of the YAG laser emitted from the dichroic mirror 16 enters the dichroic mirror 18.

The dichroic mirror 18 has the same optical characteristics as the dichroic mirror 16, and the third harmonic of the YAG laser reflected by the dichroic mirror 18 is in the form of a beam of the third harmonic of the YAG laser. The light is incident on the above-described resonator rear mirror 4 as the excitation light p through the adjusting telescope 20.

Further, the YAG incident on the dichroic mirror 18 without passing through the dichroic mirror 16 described above.
The laser fundamental wave and the second harmonic of the YAG laser are transmitted through the dichroic mirror 18 and absorbed and shielded by the beam damper 19.

[0025]

The conventional optical parametric oscillator having the above-mentioned configuration has the following problems.

(1) When the pulse repetition number of the YAG laser third harmonic that is the excitation light p or the laser output increases, the heat load acting on the excitation light blocking filter 9 when absorbing the excitation light p and the idler Wavelength selection filters 10a, 10b, 10c for absorbing the light i or the signal light s
The heat load acting on the filters increases, and these filters 9, 10
Thermal destruction may occur in a, 10b, and 10c.

(2) When the signal light s or the idler light i to be extracted passes through the pumping light blocking filter 9 and the wavelength selection filters 10a, 10b, 10c, respectively, an end face reflection loss is generated, and a signal corresponding to the end face reflection loss is received. The output of the light s or the idler light i is reduced.

(3) It is necessary to replace or switch the wavelength selection filters 10a, 10b, 10c so as to correspond to the wavelength range of the signal light s or idler light i to be extracted, which makes the handling of the apparatus complicated. .

(4) Wavelength λp of excitation light p (355 nm)
From the wavelength of the signal light s (410 to 700 nm) and the wavelength of the idler light i (730 to 2500 nm), it is very difficult to carry out the antireflection coating. Therefore, the BBO crystal 1 is not coated. Therefore, it is unavoidable to use it. Therefore, it becomes difficult to increase the output of the signal light s or the idler light i to be extracted due to the reflection loss generated at the input / output end face of the BBO crystal 1.
Also, a humidity controller 2 for protecting the BBO crystal 1 from moisture must be provided.

The present invention has been made in view of the above situation, and an object thereof is to provide an optical parametric oscillator which is easy to handle and is capable of obtaining a high-power laser beam.

[0031]

In order to achieve the above object, according to the present invention, a BBO crystal 21 which generates a signal light s and an idler light i when a YAG laser third harmonic is injected as the excitation light p. , A resonator rear mirror 22 and a resonator output mirror 23 having optical characteristics that directly face the BBO crystal 21 and resonate the signal light s generated by the BBO crystal 21, and the excitation light p incident on the resonator rear mirror 22. And an angle adjuster 6 for adjusting the angle of the BBO crystal 21 with respect to the optical parametric oscillator, which has optical characteristics of transmitting the signal light s emitted from the resonator output mirror 23 and reflecting the excitation light p. The excitation light separation dichroic mirror 24 and the signal light s that passes through the excitation light separation dichroic mirror 24 are reflected and Signal for transmitting Dora light i ·
An idler separation dichroic mirror 26 is provided, and an antireflection coating for the light in the wavelength region of the signal light s and the excitation light p is applied to the input / output end face of the BBO crystal 21.

Further, in place of the above structure, a BBO crystal 33 which generates a signal light s and an idler light i when a YAG laser third harmonic is injected as the excitation light p, and the BBO crystal 33
A resonator rear mirror 41 and a resonator output mirror 42 that directly face the BO crystal 33 and amplify the signal light s and the idler light i generated by the BBO crystal 33, and the BBO with respect to the excitation light p incident on the resonator rear mirror 41. In the optical parametric oscillator including the angle adjuster 6 for adjusting the angle of the crystal 33, the resonator output mirror 42
The excitation light separation dichroic mirror 34 which transmits the idler light i emitted from the same and reflects the excitation light p, and the idler light i which transmits the excitation light separation dichroic mirror 34 and which transmits the signal light s. A dichroic mirror for signal / idler separation 35 is provided, and an antireflection coating for the light in the wavelength region of the idler i and the excitation light p is applied to the input / output end face of the BBO crystal 33.

[0033]

In the optical parametric oscillator according to the first aspect of the present invention, the input / output end face is provided with an antireflection coating for the light in the wavelength region of the signal light s and the excitation light p.
The signal light s generated by the BO crystal 21 is resonated / amplified by the resonator rear mirror 22 and the resonator output mirror 23 having optical characteristics for resonating / amplifying the signal light s, and the excitation light separation dichroic mirror 24, the signal / Since the light is extracted by using the idler separation dichroic mirror 26, the reflection loss of the signal light s is small and the output can be increased.

In the optical parametric oscillator according to the second aspect of the present invention, the idler light i generated by the BBO crystal 33 having an anti-reflection coating on the input / output end face for the light in the wavelength region of the idler light i and the excitation light p. Are resonated / amplified by a resonator rear mirror 41 and a resonator output mirror 42 having optical characteristics for resonating / amplifying the idler light i, and a pumping light separating dichroic mirror 34 and a signal / idler separating dichroic mirror 35 are used. Since it is taken out, the reflection loss of the idler light i is small,
Higher output is possible.

[0035]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of the optical parametric oscillator of the present invention, and this embodiment corresponds to claim 1 of the present invention.

In this embodiment, the parts designated by the same reference numerals as those in FIG. 5 represent the same parts.

Reference numeral 21 is a BBO crystal, and the BBO crystal 2
An anti-reflection coating for light having a wavelength of 410 to 700 nm and light having a wavelength of 355 nm is applied to the input / output end face of 1.

Reference numeral 22 is a resonator rear mirror, 23 is a resonator output mirror, and both mirrors 22 and 23 are arranged so as to face each other.

The resonator rear mirror 22 has the property of transmitting the excitation light p and totally reflecting the light in the wavelength region of the signal light s.

The resonator output mirror 23 has a characteristic of transmitting a part (about 30%) of the signal light s and reflecting the remaining signal light s (about 70%).

The BBO crystal 21 described above is supported by the crystal angle adjuster 6 arranged in the center between the resonator rear mirror 22 and the resonator output mirror 23, and the BBO crystal 21 resonates with these. The SRO resonator (Single R) having optical characteristics that resonate the signal light s mainly by the resonator rear mirror 22 and the resonator output mirror 23.
Essonant Oscillator) is configured.

Further, the resonator rear mirror 22 has a YAG
Y with a wavelength of 1064 nm emitted from the laser oscillator 11
2nd harmonic generator of YAG laser 1
2. The YAG laser third harmonic wave having a wavelength of 355 nm sequentially converted by the YAG laser third harmonic wave generator 13 enters as the excitation light p.

A Q-sw pulse oscillation Nd: YAG laser is preferably applied to the YAG laser oscillator 1 that oscillates the YAG laser fundamental wave that is the basis of the excitation light p.

The resonator rear mirror 22 has a wavelength of 355.
When the excitation light p of nm enters, the excitation light p passes through the resonator rear mirror 22 and enters the BBO crystal 21,
In the BO crystal 21, the signal light s and the idler light i are generated based on the relationship of the above-described expression (1), and the signal light s strongly resonantly amplified by the resonator rear mirror 22 and the resonator output mirror 23. And idler light i are emitted from the resonator output mirror 23.

Reference numeral 24 is a dichroic mirror for separating excitation light, and the dichroic mirror 24 for separating excitation light is
It has a characteristic of totally reflecting the excitation light p emitted from the resonator output mirror 23 and incident at an incident angle of about 45 ° and transmitting light in the wavelength region of the signal light s.

This excitation light separation dichroic mirror 2
The excitation light p reflected by 4 is absorbed and shielded by the beam damper 25.

Further, in the excitation light separating dichroic mirror 24, a considerable amount of the idler light i emitted from the resonator output mirror 23 is also transmitted.

Reference numeral 26 denotes a signal / idler separation dichroic mirror. The signal / idler separation dichroic mirror 26 transmits the signal light s which passes through the excitation light separation dichroic mirror 24 and is incident at an incident angle of about 45 °. Of the idler light i and a characteristic of transmitting light in the wavelength range of the idler light i (however, only a part of the idler light i is reflected by the signal / idler separation dichroic mirror 26, A very small part of the signal light s passes through the signal / idler separation dichroic mirror 26).

Reference numeral 27 is a signal / idler separation dichroic mirror. The signal / idler separation dichroic mirror 27 reflects the signal light reflected by the signal / idler separation dichroic mirror 26 and is incident at an incident angle of about 45 °. It has a characteristic of totally reflecting light in the wavelength region of s and transmitting light in the wavelength region of idler light i.

The signal light s (laser light) reflected by the signal / idler separation dichroic mirror 27 is used by guiding it to a measuring instrument or a disease treatment device or irradiating a target.

The idler light i transmitted through the signal / idler separation dichroic mirror 27 is absorbed and shielded by the beam damper 28.

The signal light s finally emitted as described above
Is a dichroic mirror 2 for signal / idler separation
Since the light has passed 6 and 27, the extinction ratio of the light of the other wavelengths to the signal light s is high, and the purity of the signal light s is excellent.

Further, the signal light s reflected by the dichroic mirrors 26 and 27 for signal / idler separation is used.
Can be changed in the wavelength range of 410 to 700 nm by adjusting the angle of the BBO crystal 21 described above.

FIG. 2 shows a second embodiment of the optical parametric oscillator of the present invention, and this embodiment also corresponds to claim 1 of the present invention.

In this embodiment, the parts designated by the same reference numerals as those in FIGS. 1 and 5 represent the same parts.

Reference numeral 29 denotes a signal / idler separating dichroic mirror. The signal / idler separating dichroic mirror 29 is transmitted through the signal / idler separating dichroic mirror 26 and has an incident angle of about 4 °.
It has a characteristic of totally reflecting the light in the wavelength region of the idler light i incident at 5 ° and transmitting the light in the wavelength region of the signal light s.

The signal light s transmitted through the signal / idler separation dichroic mirror 29 is absorbed and shielded by the beam damper 30.

Reference numeral 31 denotes a signal / idler separation dichroic mirror. The signal / idler separation dichroic mirror 31 reflects the idler light reflected by the signal / idler separation dichroic mirror 29 and incident at an incident angle of about 45 °. It has the property of totally reflecting the light in the wavelength region of i and transmitting the light in the wavelength region of the signal light s.

The idler light i (laser light) reflected by the signal / idler separating dichroic mirror 31 is used by being guided to a measuring device or a disease treatment device or irradiated on a target.

The signal light s transmitted through the signal / idler separation dichroic mirror 31 is absorbed and shielded by the beam damper 32.

The idler light i finally emitted is
Is a dichroic mirror 2 for signal / idler separation
Since the light passes through 9 and 31, the extinction ratio of the light of other wavelengths to the idler light i is high, and the output is considerably inferior to the signal light s reflected by the signal / idler separation dichroic mirror 27 described above. The purity of the idler light i is excellent.

Idler light i reflected by the dichroic mirrors 29 and 31 for signal / idler separation is also used.
Can be changed within the wavelength range of 730 to 2500 nm by adjusting the angle of the BBO crystal 21 described above.

FIG. 3 shows a third embodiment of the optical parametric oscillator of the present invention, and this embodiment corresponds to claim 2 of the present invention.

In this embodiment, the parts designated by the same reference numerals as those in FIGS. 1, 2 and 5 represent the same parts.

33 is a BBO crystal, and the BBO crystal 3
An antireflection coating for light having a wavelength of 730 to 2500 nm and light having a wavelength of 355 nm is applied to the entrance and exit end faces of No. 3.

Reference numeral 41 is a resonator rear mirror, 42 is a resonator output mirror, and both mirrors 41 and 42 are arranged so as to face each other.

The resonator rear mirror 41 has the characteristic of transmitting the excitation light p and totally reflecting the light in the wavelength region of the idler light i.

The resonator output mirror 42 has a characteristic of transmitting a part (about 20%) of the idler light i and reflecting the remaining idler light i (about 80%).

The BBO crystal 33 described above is supported by the crystal angle adjuster 6 arranged at the center between the resonator rear mirror 41 and the resonator output mirror 42, and resonates with the BBO crystal 33. The SRO resonator (Single R) having optical characteristics that resonate the idler light i mainly by the device rear mirror 41 and the resonator output mirror 42.
Essonant Oscillator) is configured.

The resonator rear mirror 41 has a wavelength of 355.
When the excitation light p of nm enters, the excitation light p passes through the resonator rear mirror 41 and enters the BBO crystal 33,
In the BO crystal 33, the signal light s and the idler light i are generated based on the relationship of the above-described formula (1), and the idler light i strongly resonantly amplified by the resonator rear mirror 41 and the resonator output mirror 42. And the signal light s are emitted from the resonator output mirror 42.

Reference numeral 34 is a dichroic mirror for excitation light separation, and the dichroic mirror 34 for excitation light separation is
It has a characteristic of totally reflecting the excitation light p emitted from the resonator output mirror 42 and incident at an incident angle of about 45 ° and transmitting light in the wavelength region of the idler light i.

This excitation light separation dichroic mirror 3
The excitation light p reflected by 4 is absorbed and shielded by the beam damper 25.

Further, in the excitation light separation dichroic mirror 34, a considerable amount of the signal light s emitted from the resonator output mirror 42 is also transmitted.

Reference numeral 35 denotes a signal / idler separation dichroic mirror. The signal / idler separation dichroic mirror 35 is transmitted through the excitation light separation dichroic mirror 34 and is incident on the idler light i at an incident angle of about 45 °. Has a property of totally reflecting light in the wavelength region of (1) and transmitting light in the wavelength region of signal light s (however, only a part of signal light s is reflected by the signal / idler separation dichroic mirror 35 and A very small portion of the idler light i passes through the signal / idler separation dichroic mirror 35).

Reference numeral 36 denotes a signal / idler separating dichroic mirror. The signal / idler separating dichroic mirror 36 reflects the idler light reflected by the signal / idler separating dichroic mirror 35 and incident at an incident angle of about 45 °. It has the property of totally reflecting the light in the wavelength region of i and transmitting the light in the wavelength region of the signal light s.

The idler light i (laser light) reflected by the signal / idler separation dichroic mirror 36 is guided to a measuring instrument, a disease treatment apparatus, or the like and is used by irradiating a target.

The signal light s transmitted through the signal / idler separation dichroic mirror 36 is absorbed and shielded by the beam damper 28.

The idler light i finally emitted as described above
Is a dichroic mirror 3 for signal / idler separation
Since the light passes through 5 and 36, the extinction ratio of the light of other wavelengths to the idler light i is high, and the purity of the idler light i is excellent.

Further, the idler light i reflected by the signal / idler separation dichroic mirrors 35, 36 is i.
Can be changed in the wavelength range of 730 to 250 nm by adjusting the angle of the BBO crystal 33 described above.

FIG. 4 shows a fourth embodiment of the optical parametric oscillator of the present invention, and this embodiment also corresponds to claim 2 of the present invention.

In this embodiment, the parts designated by the same reference numerals as those in FIGS. 1 to 3 and 5 represent the same parts.

Reference numeral 37 denotes a signal / idler separation dichroic mirror. The signal / idler light separation dichroic mirror 37 transmits a signal which is transmitted through the signal / idler separation dichroic mirror 35 and is incident at an incident angle of about 45 °. It has a characteristic of totally reflecting the light in the wavelength range of the light s and transmitting the light in the wavelength range of the idler light i.

The idler light i transmitted through the signal / idler separation dichroic mirror 37 is absorbed and shielded by the beam damper 30.

Reference numeral 38 denotes a signal / idler separating dichroic mirror. The signal / idler separating dichroic mirror 38 reflects the signal light reflected by the signal / idler separating dichroic mirror 37 and enters at an incident angle of about 45 °. It has a characteristic of totally reflecting light in the wavelength region of s and transmitting light in the wavelength region of idler light i.

The signal light s (laser light) reflected by the signal / idler separation dichroic mirror 38 is used by guiding it to a measuring instrument or a disease treatment apparatus or irradiating a target.

The idler light i transmitted through the signal / idler separation dichroic mirror 38 is absorbed and shielded by the beam damper 32.

The finally emitted signal light s
Is a dichroic mirror 3 for signal / idler separation
7 and 38, the extinction ratio of the light of other wavelengths to the signal light s is high, and the output is inferior to the idler light i reflected by the signal / idler separation dichroic mirror 36 described above. Signal light s
The purity is excellent.

Further, the signal light s reflected by the dichroic mirrors 37 and 38 for signal / idler separation is used.
Can be changed in the wavelength range of 410 to 700 nm by adjusting the angle of the BBO crystal 33 described above.

Needless to say, each dichroic mirror in each of the above-described embodiments is a mirror in which a dielectric multilayer film is vapor-deposited (coated) on a substrate such as quartz or BK7.

Further, the optical parametric oscillator of the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the scope of the present invention.

[0092]

As described above, according to the optical parametric oscillator of the present invention, since the light in the main wavelength range to be extracted is limited to either the signal light s or the idler light i, the wavelength range is relatively large. B by limitation
It becomes possible to realize a high-performance coating on the BO crystals 21 and 33, and it is possible to exhibit various excellent effects as described below.

(1) In the optical parametric oscillator according to claim 1 of the present invention, since the excitation light separation dichroic mirror 24 and the signal / idler separation dichroic mirror 26 are used in the wavelength separation optical system, the wavelength selection is performed. At this time, it is not necessary to replace or switch optical elements such as mirrors, and thermal destruction of the optical elements is less likely to occur even if the number of pulse repetitions of the excitation light and the output thereof are increased.

(2) In the optical parametric oscillator according to claim 2 of the present invention, since the excitation light separation dichroic mirror 34 and the signal / idler separation dichroic mirror 35 are used in the wavelength separation optical system, the wavelength selection is performed. At this time, it is not necessary to replace or switch optical elements such as mirrors, and thermal destruction of the optical elements is less likely to occur even if the number of pulse repetitions of the excitation light and the output thereof are increased.

(3) In the optical parametric oscillator according to claim 1 of the present invention, a BB with an antireflection coating is provided.
SR that resonates the signal light s mainly by the O crystal 21, the resonator rear mirror 22, and the resonator output mirror 23.
Since the O resonator is configured, there is almost no reflection loss of the signal light s, and the signal light s can be extracted with high efficiency.

(4) In the optical parametric oscillator according to claim 2 of the present invention, a BB with an antireflection coating is provided.
SR in which the idler light i is mainly resonated by the O crystal 33, the resonator rear mirror 41, and the resonator output mirror 42.
Since the O resonator is configured, there is almost no reflection loss of the idler light i, and the idler light i can be extracted with high efficiency.

(5) In the optical parametric oscillator according to claim 1 of the present invention, since the input / output end face of the BBO crystal 21 is provided with an antireflection coating, the BBO crystal 2
No equipment such as a humidity controller for protecting the No. 1 from moisture is required, and the apparatus can be downsized and maintenance can be simplified.

(6) In the optical parametric oscillator according to the second aspect of the present invention, the BBO crystal 33 is provided with the antireflection coating on the input / output end faces thereof.
No equipment such as a humidity controller for protecting the No. 3 from humidity is required, and the apparatus can be downsized and maintenance can be simplified.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a first embodiment of an optical parametric oscillator of the present invention.

FIG. 2 is a conceptual diagram showing a second embodiment of the optical parametric oscillator of the present invention.

FIG. 3 is a conceptual diagram showing a third embodiment of the optical parametric oscillator of the present invention.

FIG. 4 is a conceptual diagram showing a fourth embodiment of the optical parametric oscillator of the present invention.

FIG. 5 is a conceptual diagram showing an example of a conventional optical parametric oscillator.

[Explanation of symbols]

6 crystal angle adjuster (angle adjuster) 21, 33 BBO crystal 22, 39, 41 resonator rear mirror 23, 40, 42 resonator output mirror 24, 34 excitation light separation dichroic mirror 26, 27, 29, 31, 35 , 36, 37, 38
Dichroic mirror for signal / idler separation p Excitation light s Signal light i Idler light

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsushi Inoue 3-15-15 Toyosu, Koto-ku, Tokyo Ishikawajima Harima Heavy Industries, Ltd. Toni Technical Center (72) Seiji Fukutomi 3-chome, Toyosu, Koto-ku, Tokyo No. 1-15 Ishikawajima Harima Heavy Industries Co., Ltd. Toni Technical Center (72) Inventor Takeshi Udagawa 3-15-15 Toyosu, Koto-ku, Tokyo Ishikawajima Harima Heavy Industries Co., Ltd. Toji Technical Center

Claims (2)

[Claims] 1. A BBO crystal (21) which generates a signal light (s) and an idler light (i) when a YAG laser third harmonic is incident as excitation light (p), and the BBO crystal (21). ), And a resonator rear mirror (22) and a resonator output mirror (23) having optical characteristics that resonate the signal light (s) generated by the BBO crystal (21), and the BBO for the excitation light (p). Crystal (21)
And an angle adjuster (6) for adjusting the angle of the resonator output mirror (2).
3) Excitation light separation dichroic mirror (24) having optical characteristics of transmitting the signal light (s) emitted from the same and reflecting excitation light (p), and transmitting through the excitation light separation dichroic mirror (24) A signal / idler separation dichroic mirror (26) that reflects the signal light (s) and transmits the idler light (i),
An optical parametric oscillator, characterized in that the BBO crystal (21) is provided with an anti-reflection coating on the input and output end faces for the light in the wavelength region of the signal (s) and the excitation light (p). 2. A BBO crystal (33) which generates a signal light (s) and an idler light (i) when a YAG laser third harmonic is incident as the excitation light (p), and the BBO crystal (33). ), And a resonator rear mirror (41) and a resonator output mirror (42) for amplifying the signal light (s) and the idler light (i) generated by the BBO crystal (33), and the resonator rear mirror (42). 41) An optical parametric oscillator including an angle adjuster (6) for adjusting the angle of the BBO crystal (33) with respect to the excitation light (p) incident on the idler emitted from the resonator output mirror (42). The excitation light separation dichroic mirror (34) which transmits the light (i) and reflects the excitation light (p) and the idler light (i) which transmits the excitation light separation dichroic mirror (34) are reversed. A dichroic mirror for signal / idler separation (35) that emits and transmits the signal light (s) is provided, and light in the wavelength region of the idler (i) and excitation light ( An optical parametric oscillator characterized by being coated with an antireflection coating for p) and.