阅读说明：本技术 人眼安全波段级联倍频光学参量振荡器 (Human eye safety wave band cascade frequency doubling optical parametric oscillator ) 是由 檀慧明 姚文明 高静 田玉冰 *** 王鹏 于 2020-06-05 设计创作，主要内容包括：本发明公开了一种人眼安全波段级联倍频光学参量振荡器,包括：泵浦光源、输入镜、参量转换晶体、倍频晶体和输出镜；输入镜与输出镜构成人眼安全波段级联倍频光学参量振荡器谐振腔,泵浦光源输出1μm-1.1μm的泵浦光至参量转换晶体,产生信号光和闲频光,所述闲频光在所述光学参量振荡器谐振腔内振荡,并通过所述倍频晶体频率变换为波长在1.5μm到1.8μm人眼安全波段的倍频光,所述倍频光与信号光共同通过所述输出镜输出。本发明通过把人眼安全波段光学参量振荡器的无用闲频光频率变换为人眼安全波段的倍频光,克服了的人眼安全波段光学参量振荡器的闲频光能量损失的问题,提高了泵浦光到人眼安全波长的转换效率。(The invention discloses a cascade frequency multiplication optical parametric oscillator of a human eye safety wave band, which comprises: the device comprises a pumping light source, an input mirror, a parametric conversion crystal, a frequency doubling crystal and an output mirror; the input mirror and the output mirror form a human eye safe waveband cascade frequency doubling optical parametric oscillator resonant cavity, a pump light source outputs pump light with the wavelength of 1-1.1 mu m to a parametric conversion crystal to generate signal light and idler light, the idler light oscillates in the optical parametric oscillator resonant cavity and is converted into frequency doubling light with the wavelength of the human eye safe waveband of 1.5-1.8 mu m through the frequency doubling crystal, and the frequency doubling light and the signal light are output through the output mirror together. According to the invention, the useless idler frequency light frequency of the human eye safe waveband optical parametric oscillator is converted into the frequency doubling light of the human eye safe waveband, so that the problem of energy loss of the idler frequency light of the human eye safe waveband optical parametric oscillator is solved, and the conversion efficiency of the pump light to the human eye safe wavelength is improved.)

1. A cascade frequency doubling optical parametric oscillator with human eye safety wave bands is characterized by comprising: the device comprises a pumping light source, an input mirror, a parametric conversion crystal, a frequency doubling crystal and an output mirror;

the input mirror and the output mirror form a human eye safe waveband cascade frequency doubling optical parametric oscillator resonant cavity, the pump light source outputs pump light with the wavelength of 1-1.1 mu m to the parametric conversion crystal to generate signal light with the wavelength of 1.5-1.8 mu m in the human eye safe waveband and idle light with the wavelength not in the human eye safe waveband, the idle light oscillates in the optical parametric oscillator resonant cavity and is converted into frequency doubling light with the wavelength of 1.5-1.8 mu m in the human eye safe waveband through the frequency doubling crystal, and the frequency doubling light and the signal light are output together through the output mirror as laser with the human eye safe wavelength.

2. The eye-safe band cascaded frequency-doubled optical parametric oscillator of claim 1, wherein the eye-safe band cascaded frequency-doubled optical parametric oscillator resonant cavity formed by the input mirror and the output mirror is an idler single-wavelength resonant, nonlinear frequency-doubled output optical parametric oscillator resonant cavity.

3. The eye-safe wavelength band cascaded frequency-doubled optical parametric oscillator of claim 2, wherein the signal light and the frequency-doubled light are lasers in the eye-safe wavelength band with the same wavelength but a vertical polarization direction;

or the signal light and the frequency doubling light are lasers in a human eye safe waveband, wherein the wavelengths of the signal light and the frequency doubling light are different, and the wavelength ranges of frequency doubling frequency conversion of idler frequency light and signal light inverse conversion are not overlapped.

4. The eye-safe band cascaded frequency-doubled optical parametric oscillator of claim 3, wherein the parametric conversion crystal is: MgO, PPLN, PPKTA, PPRTA, KTA, RTA or KTP.

5. The eye-safe waveband cascade frequency doubling optical parametric oscillator of claim 4, wherein the frequency doubling crystal is: PPLN, LiNbO as MgO₃、LiNbO₃PPKTA, PPRTA, KTA, RTA or KTP.

6. The cascaded frequency-doubled optical parametric oscillator according to claim 5, wherein the cascaded frequency-doubled optical parametric oscillator for a human eye safe waveband is a straight cavity without a coupling lens.

7. The cascade frequency-doubling optical parametric oscillator according to claim 5, further comprising a coupling lens and a catadioptric mirror;

the pump light output by the pump light source sequentially passes through the coupling lens and the input mirror and then is incident into the parametric conversion crystal, and the parametric conversion crystal generates the signal light and the idler frequency light; the residual pump light is transmitted through the folding mirror and then emitted out of the resonant cavity of the optical parametric oscillator, the signal light and the idler light are reflected into the frequency doubling crystal through the folding mirror, the idler light is converted into frequency doubling light with the wavelength at the safe waveband for human eyes through frequency doubling frequency, the signal light directly passes through the frequency doubling crystal and is output by the output mirror together with the frequency doubling light, and the residual idler light after frequency doubling frequency conversion continues to oscillate in the resonant cavity of the optical parametric oscillator after being reflected by the output mirror.

8. The eye-safe wavelength band cascaded frequency-doubled optical parametric oscillator of claim 7, further comprising a mirror;

the pump light output by the pump light source sequentially passes through the coupling lens and the input mirror and then is incident into the parametric conversion crystal, and the parametric conversion crystal generates the signal light and the idler frequency light; the rest of the pump light is transmitted through the catadioptric mirror and then is emitted out of the optical parametric oscillator resonant cavity; the signal light and the idler frequency light are reflected to the reflecting mirror through the folding reflecting mirror and then reflected to the frequency doubling crystal through the reflecting mirror, the idler frequency light is converted into frequency doubling light with the wavelength at a safe waveband for human eyes through frequency doubling frequency, and the signal light and the frequency doubling light directly pass through the frequency doubling crystal and are output by the output mirror together; and the rest idle frequency light after the frequency doubling frequency conversion is reflected to the input mirror by the output mirror and then continues to oscillate in the resonant cavity of the optical parametric oscillator.

9. The human-eye-safe waveband cascade frequency-doubling optical parametric oscillator according to claim 5, wherein the pumping light source comprises a laser input cavity mirror, a laser gain medium, a passive Q-switching crystal and the shared output mirror, the laser input cavity mirror and the output mirror form a laser resonant cavity of the pumping light source, and the input mirror, the parametric conversion crystal and the frequency doubling crystal are arranged in the laser resonant cavity;

pumping laser of the laser resonant cavity is incident into the laser gain medium through the laser input cavity mirror, the laser gain medium generates spontaneous radiation, pulse laser is generated through saturable absorption of the passive Q-switched crystal, the pulse laser oscillates in the laser resonant cavity, and is output as pumping light through the input mirror and is incident into the parametric conversion crystal, and parametric conversion generates signal light and idle frequency light; the residual pump light, signal light and idler frequency light are jointly incident into the frequency doubling crystal, the idler frequency light is converted into frequency doubling light with the wavelength in a human eye safe wave band through frequency doubling frequency, and the frequency doubling light and the signal light are jointly output by the output mirror as laser with the human eye safe wavelength; and the residual pumping light and the residual idler frequency light are reflected by the output mirror and then continue to oscillate in the laser resonant cavity and the optical parametric oscillator resonant cavity respectively.

10. The human-eye-safe waveband cascade frequency-doubling optical parametric oscillator according to claim 5, further comprising a catadioptric mirror, and the pumping light source comprises a laser input cavity mirror, a laser gain medium, a passive Q-switched crystal and a laser high-reflection mirror, the laser input cavity mirror and the laser high-reflection mirror constitute a laser resonant cavity of the pumping light source, and the input mirror, the parametric conversion crystal and the catadioptric mirror are disposed in the laser resonant cavity;

pumping laser of the laser resonant cavity is incident into the laser gain medium through the laser input cavity mirror, the laser gain medium generates spontaneous radiation, pulse laser is generated through saturable absorption of the passive Q-switched crystal, the pulse laser oscillates in the laser resonant cavity, and is output as pumping light through the input mirror and is incident into the parametric conversion crystal, and parametric conversion generates signal light and idle frequency light;

the residual pump light is reflected back to the laser resonant cavity by the laser high-reflection mirror after transmitting the catadioptric mirror and oscillates in the laser resonant cavity;

the signal light and the idler frequency light are reflected into the frequency doubling crystal through the catadioptric mirror, the idler frequency light is converted into frequency doubling light with the wavelength in a human eye safe waveband through frequency doubling frequency, the signal light directly passes through the frequency doubling crystal and the frequency doubling light and is output by the output mirror together, and the rest of the idler frequency light after frequency doubling frequency conversion continues to oscillate in the optical parametric oscillator resonant cavity after being reflected by the output mirror.

Technical Field

The invention relates to the technical field of optical parametric oscillators, in particular to a human eye safe wave band cascade frequency multiplication optical parametric oscillator.

Background

Laser light having a wavelength in the band between 1.5 μm and 1.8 μm enters the human eye and is absorbed by the crystalline lens in the cornea before reaching the retina without damaging the fundus, and the wavelength in this band is called the eye-safe wavelength. Lasers with wavelengths safe for human eyes have been widely used in the fields of laser ranging, topographic mapping, space communication, laser radar, and the like.

At present, an optical parametric oscillator adopting laser pumping with the wavelength of 1-1.1 μm is a main technical scheme for obtaining the output of wavelength laser safe for human eyes. Patent No. US 5,181,211 proposes pumping a non-critical phase-matched KTP optical parametric oscillator with an all-solid-state laser of 1 μm to 1.1 μm, obtaining signal light in the eye-safe band and idler light not in the eye-safe band. In such an optical parametric oscillator, the energy of the idler light occupies about one third of the total conversion energy of the pump light, and is removed as waste light outside the cavity or absorbed by an element in the cavity, limiting the conversion efficiency of the wavelength safe to human eyes.

Disclosure of Invention

The invention aims to solve the technical problem of providing a human eye safe wave band cascade frequency doubling optical parametric oscillator aiming at the defects in the prior art.

In order to solve the technical problems, the invention adopts the technical scheme that: a human eye safe waveband cascade frequency multiplication optical parametric oscillator comprises: the device comprises a pumping light source, an input mirror, a parametric conversion crystal, a frequency doubling crystal and an output mirror;

the input mirror and the output mirror form a human eye safe waveband cascade frequency doubling optical parametric oscillator resonant cavity, the pump light source outputs pump light with the wavelength of 1-1.1 mu m to the parametric conversion crystal to generate signal light with the wavelength of 1.5-1.8 mu m in the human eye safe waveband and idle light with the wavelength not in the human eye safe waveband, the idle light oscillates in the optical parametric oscillator resonant cavity and is converted into frequency doubling light with the wavelength of 1.5-1.8 mu m in the human eye safe waveband through the frequency doubling crystal, and the frequency doubling light and the signal light are output together through the output mirror as laser with the human eye safe wavelength.

Preferably, the human eye safe waveband cascade frequency doubling optical parametric oscillator resonant cavity formed by the input mirror and the output mirror is an idler frequency optical single-wavelength resonant and nonlinear frequency doubling output optical parametric oscillator resonant cavity.

Preferably, the signal light and the frequency doubling light are laser light in a safety wavelength band for human eyes, and the wavelength of the laser light is the same as that of the frequency doubling light, but the polarization direction of the laser light is vertical;

or the signal light and the frequency doubling light are lasers in a human eye safe waveband, wherein the wavelengths of the signal light and the frequency doubling light are different, and the wavelength ranges of frequency doubling frequency conversion of idler frequency light and signal light inverse conversion are not overlapped.

Preferably, the parametric conversion crystal is: MgO, PPLN, PPKTA, PPRTA, KTA, RTA or KTP.

Preferably, the frequency doubling crystal is: PPLN, LiNbO as MgO₃、LiNbO₃PPKTA, PPRTA, KTA, RTA or KTP.

Preferably, the human eye safe waveband cascade frequency multiplication optical parametric oscillator is in a straight cavity type without a coupling lens.

Preferably, the device further comprises a coupling lens and a catadioptric mirror;

the pump light output by the pump light source sequentially passes through the coupling lens and the input mirror and then is incident into the parametric conversion crystal, and the parametric conversion crystal generates the signal light and the idler frequency light; the residual pump light is transmitted through the folding mirror and then emitted out of the resonant cavity of the optical parametric oscillator, the signal light and the idler light are reflected into the frequency doubling crystal through the folding mirror, the idler light is converted into frequency doubling light with the wavelength at the safe waveband for human eyes through frequency doubling frequency, the signal light directly passes through the frequency doubling crystal and is output by the output mirror together with the frequency doubling light, and the residual idler light after frequency doubling frequency conversion continues to oscillate in the resonant cavity of the optical parametric oscillator after being reflected by the output mirror.

Preferably, a reflector is also included;

the pump light output by the pump light source sequentially passes through the coupling lens and the input mirror and then is incident into the parametric conversion crystal, and the parametric conversion crystal generates the signal light and the idler frequency light; the rest of the pump light is transmitted through the catadioptric mirror and then is emitted out of the optical parametric oscillator resonant cavity; the signal light and the idler frequency light are reflected to the reflecting mirror through the folding reflecting mirror and then reflected to the frequency doubling crystal through the reflecting mirror, the idler frequency light is converted into frequency doubling light with the wavelength at a safe waveband for human eyes through frequency doubling frequency, and the signal light and the frequency doubling light directly pass through the frequency doubling crystal and are output by the output mirror together; and the rest idle frequency light after the frequency doubling frequency conversion is reflected to the input mirror by the output mirror and then continues to oscillate in the resonant cavity of the optical parametric oscillator.

Preferably, the pumping light source comprises a laser input cavity mirror, a laser gain medium, a passive Q-switched crystal and the shared output mirror, the laser input cavity mirror and the output mirror form a laser resonant cavity of the pumping light source, and the input mirror, the parametric conversion crystal and the frequency doubling crystal are arranged in the laser resonant cavity;

pumping laser of the laser resonant cavity is incident into the laser gain medium through the laser input cavity mirror, the laser gain medium generates spontaneous radiation, pulse laser is generated through saturable absorption of the passive Q-switched crystal, the pulse laser oscillates in the laser resonant cavity, and is output as pumping light through the input mirror and is incident into the parametric conversion crystal, and parametric conversion generates signal light and idle frequency light; the residual pump light, signal light and idler frequency light are jointly incident into the frequency doubling crystal, the idler frequency light is converted into frequency doubling light with the wavelength in a human eye safe wave band through frequency doubling frequency, and the frequency doubling light and the signal light are jointly output by the output mirror as laser with the human eye safe wavelength; the residual pumping light and the residual idler frequency light are reflected by the output mirror and then continue to respectively oscillate in the laser resonant cavity and the optical parametric oscillator resonant cavity;

preferably, the laser device further comprises a catadioptric mirror, and the pumping light source comprises a laser input cavity mirror, a laser gain medium, a passive Q-switched crystal and a laser high-reflection mirror, the laser input cavity mirror and the laser high-reflection mirror form a laser resonant cavity of the pumping light source, and the input mirror, the parametric conversion crystal and the catadioptric mirror are arranged in the laser resonant cavity;

pumping laser of the laser resonant cavity is incident into the laser gain medium through the laser input cavity mirror, the laser gain medium generates spontaneous radiation, pulse laser is generated through saturable absorption of the passive Q-switched crystal, the pulse laser oscillates in the laser resonant cavity, and is output as pumping light through the input mirror and is incident into the parametric conversion crystal, and parametric conversion generates signal light and idle frequency light;

the residual pump light is reflected back to the laser resonant cavity by the laser high-reflection mirror after transmitting the catadioptric mirror and oscillates in the laser resonant cavity;

the signal light and the idler frequency light are reflected into the frequency doubling crystal through the catadioptric mirror, the idler frequency light is converted into frequency doubling light with the wavelength in a human eye safe waveband through frequency doubling frequency, the signal light directly passes through the frequency doubling crystal and the frequency doubling light and is output by the output mirror together, and the rest of the idler frequency light after frequency doubling frequency conversion continues to oscillate in the optical parametric oscillator resonant cavity after being reflected by the output mirror.

The invention has the beneficial effects that: according to the human eye safe waveband cascade frequency doubling optical parametric oscillator, the useless idler frequency light frequency of the human eye safe waveband optical parametric oscillator is converted into the frequency doubling light of the human eye safe waveband, the problem of idler frequency light energy loss of the human eye safe waveband optical parametric oscillator is solved, and the conversion efficiency of pump light to human eye safe wavelength is improved.

Drawings

Fig. 1 is a schematic structural diagram of a human eye safe waveband cascade frequency doubling optical parametric oscillator in embodiment 1 of the present invention;

fig. 2 is a schematic structural diagram of a human eye safe waveband cascade frequency doubling optical parametric oscillator in embodiment 3 of the present invention;

fig. 3 is a schematic structural diagram of a human eye safe waveband cascade frequency doubling optical parametric oscillator according to embodiment 4 of the present invention;

fig. 4 is a schematic structural diagram of a human eye safe waveband cascade frequency doubling optical parametric oscillator in embodiment 5 of the present invention.

Detailed Description

The present invention is further described in detail below with reference to examples so that those skilled in the art can practice the invention with reference to the description.

It will be understood that terms such as "having," "including," and "comprising," as used herein, do not preclude the presence or addition of one or more other elements or groups thereof.

The cascade frequency-doubling optical parametric oscillator with the human eye safety waveband of the embodiment comprises: a pumping light source 101, an input mirror 103, a parametric conversion crystal 104, a frequency doubling crystal 106 and an output mirror 107;

the input mirror 103 and the output mirror 107 form a human eye safe waveband cascade frequency doubling optical parametric oscillator resonant cavity, the pump light source 101 outputs pump light with a wavelength of 1 μm to 1.1 μm to the parametric conversion crystal 104, signal light with a wavelength of 1.5 μm to 1.8 μm in a human eye safe waveband and idler light with a wavelength not in the human eye safe waveband are generated, the idler light oscillates in the optical parametric oscillator resonant cavity and is frequency-converted into frequency doubling light with a wavelength of 1.5 μm to 1.8 μm in the human eye safe waveband through the frequency doubling crystal 106, and the frequency doubling light and the signal light are output through the output mirror 107 together as light with the human eye safe wavelength.

The human eye safe waveband cascade frequency doubling optical parametric oscillator resonant cavity formed by the input mirror 103 and the output mirror 107 is an idle frequency optical single-wavelength resonant and nonlinear frequency doubling output optical parametric oscillator resonant cavity.

The signal light and the frequency doubling light are laser with the same wavelength and the vertical polarization direction in a safety wave band of human eyes;

or the signal light and the frequency doubling light are lasers in a human eye safe waveband, wherein the wavelengths of the signal light and the frequency doubling light are different, and the wavelength ranges of frequency doubling frequency conversion of idler frequency light and signal light inverse conversion are not overlapped.

Wherein the parametric conversion crystal 104 is: MgO, PPLN, PPKTA, PPRTA, KTA, RTA or KTP. The frequency doubling crystal 106 is: PPLN, LiNbO as MgO₃、LiNbO₃PPKTA, PPRTA, KTA, RTA or KTP.

For the structural form of cascade frequency doubling optical parametric oscillation of the human eye safe waveband, an inner cavity type structure and an outer cavity type structure can be respectively formed by arranging an optical parametric oscillator resonant cavity in a cavity or outside a cavity of a laser resonant cavity of a pump light source 101; the resonant cavity of the optical parametric oscillator and the resonant cavity of the laser can share part of elements or add part of elements to form different structural forms capable of realizing the functions, such as a straight cavity type or folding human eye safe wave band cascade frequency doubling optical parametric oscillator (an outer cavity type), a four-mirror ring cavity human eye safe wave band cascade frequency doubling optical parametric oscillator (an outer cavity type), an inner cavity type human eye safe wave band cascade frequency doubling optical parametric oscillator (an inner cavity type), a composite human eye safe wave band cascade frequency doubling optical parametric oscillator (a semi-inner cavity type) and the like.

The foregoing is a general idea of the present invention, and specific examples based on it are provided below for detailed description.