CN115000790B - Pulse middle-far infrared laser optical parametric oscillator with low pumping threshold and high conversion efficiency - Google Patents
Pulse middle-far infrared laser optical parametric oscillator with low pumping threshold and high conversion efficiency Download PDFInfo
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- CN115000790B CN115000790B CN202210630949.4A CN202210630949A CN115000790B CN 115000790 B CN115000790 B CN 115000790B CN 202210630949 A CN202210630949 A CN 202210630949A CN 115000790 B CN115000790 B CN 115000790B
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- H—ELECTRICITY
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- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/11—Mode locking; Q-switching; Other giant-pulse techniques, e.g. cavity dumping
- H01S3/1123—Q-switching
- H01S3/117—Q-switching using intracavity acousto-optic devices
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/08—Construction or shape of optical resonators or components thereof
- H01S3/081—Construction or shape of optical resonators or components thereof comprising three or more reflectors
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- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/106—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity
- H01S3/108—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity using non-linear optical devices, e.g. exhibiting Brillouin or Raman scattering
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Abstract
The invention provides a pulse middle-far infrared laser optical parametric oscillator with low pumping threshold and high conversion efficiency, which comprises the following components: the laser pump comprises a laser pumping source, an optical parametric resonant cavity, a plurality of parametric crystals, a frequency doubling crystal and a plurality of reflectors; the optical parametric resonant cavity comprises a double-square resonant cavity formed by a first square resonant light path and a second square resonant light path; each reflecting mirror forms a preset included angle with the optical axis of the resonant light path; a first back-shaped resonant light path and a second back-shaped resonant light path of the optical parametric resonant cavity are formed; the laser of the laser pumping source is injected into the first back-shaped resonant light path and the second back-shaped resonant light path through the first reflecting mirror M1, and the frequency doubling crystal is arranged between the second reflecting mirror M2 and the third reflecting mirror M3; or between the fifth mirror M5 and the sixth mirror M6; the parametric crystal is placed between the first mirror M1 and the second mirror M2 and between the third mirror M3 and the fourth mirror M4; the fourth mirror M4 is an idler light output mirror.
Description
Technical Field
The invention belongs to the technical field of nonlinear laser crystals, and particularly relates to a pulse middle-far infrared laser optical parametric oscillator with low pumping threshold and high conversion efficiency.
Background
Currently, mid-far infrared lasers have wide and important applications in the fields of photoelectric countermeasure, environmental monitoring, medicine, molecular spectroscopy, and the like. The Optical Parametric Oscillator (OPO) can convert mature 1 mu m laser into middle-far infrared laser, and has the advantages of full solidification, miniaturization, adjustable output wavelength broadband, simple structure and the like.
However, in the OPO of pulse laser pumping, the low pumping threshold and the high pumping conversion efficiency are contradiction, and when the pumping energy is lower under the condition that the reflectivity of the OPO cavity mirror to the signal light is higher, the signal light in the cavity can also oscillate and be enhanced to be near the threshold energy, so that the pumping threshold is lower; when the pumping energy is higher, the power density of the signal light in the cavity is too high, and at the moment, the signal light can be reversely converted into the pumping light, and the conversion efficiency of the pumping light can be seriously influenced in the reverse conversion process, so that the pumping conversion efficiency is lower. Under the condition that the reflectivity of the OPO cavity mirror to the signal light is low, when the pumping energy is low, the signal light in the cavity is difficult to oscillate and enhance to the vicinity of the threshold energy, so that the pumping threshold is high; when the pump energy is higher, the reflectivity of the cavity mirror is lower, so that the signal optical power density in the cavity is not too high, and the reverse conversion degree is smaller at the moment, so that the pump conversion efficiency is higher.
In addition, there are cases where the degree of reverse conversion is spatially and temporally inconsistent within the same OPO lumen. The pulse pump laser generally follows Gaussian distribution in space and time, and the pump light energy is strong and the reverse conversion degree is high at the pulse time center and the light spot center; the pump light energy is weaker and the reverse conversion degree is lower at the pulse starting section, the pulse ending section and the light spot edge; imbalance in the degree of reverse conversion in the OPO cavity is also a significant cause of contradiction between low threshold and high conversion efficiency.
The most common technical means for reducing the threshold is to increase the reflectivity of the OPO cavity mirror to the signal light. In 2002, the open-width-and-close et al obtained mid-infrared laser output with a low pumping threshold using an OPO cavity mirror with high reflectivity to the signal light. Under the condition that the PPLN output of the laser pump with the diameter of 1.06 mu m is 2.12 mu m, when the reflectivity of the cavity mirror before and after OPO to the signal light is 99.8 percent and 99.2 percent respectively, the pump threshold value is only 1.5mW, but the output mid-infrared laser energy is smaller. When the pump energy is 4 times the threshold power, the conversion efficiency is 15%. It is mentioned that if the transmittance of the OPO cavity mirror to the signal light is improved, a higher power mid-infrared laser output can be obtained under the same design conditions.
The most common technical means for improving the pump conversion efficiency is to reduce the reflectivity of the OPO cavity mirror to the signal light. In 2017, wang L et al obtained mid-infrared laser output with high conversion efficiency using an OPO cavity mirror with low reflectivity to signal light. When the 2.09 mu m laser pump ZGP outputs 3.6-4.8 mu m laser, the highest conversion efficiency reaches 75.7% when the reflectivity of the OPO front and rear cavity mirrors to the signal light is respectively high reflection and 50%.
In addition to the effect that OPO cavity mirror reflectivity can have on pump threshold and pump conversion efficiency, absorption of parametric light by nonlinear crystals can also affect threshold and conversion efficiency. Taking 1.06um pump KTP and KTA output human eye safety wave band laser (1.6 um) as an example, parametric light (3.2 um) oscillates in the OPO cavity at this time, because KTP is higher than KTA in absorption of 3.2um wave band, loss is larger when KTP oscillates in the cavity, so the pumping threshold of KTP OPO is higher than KTA OPO under the same design condition, but conversion efficiency is higher than KTA OPO. In 2015, li H et al output 1.57um laser with 1.06um laser pump KTA OPO, with a conversion efficiency of about 26%. Under similar conditions, in 2018, M.Kaskow et al output 1.57um laser with 1.06um laser local pump KTP OPO with a conversion efficiency of about 51%.
Other methods for improving the pump conversion efficiency have been explored by researchers, such as frequency doubling the pump light and the signal light by using parametric crystals to consume the signal light, pumping the parametric crystals with dual-wavelength laser, and the like.
In 2015, jiang Tao et al used the sum frequency of pump-generated signal light (1300-1500 nm) and pump light (1064 nm) to generate red-orange light, and reduced the intensity of signal light in the cavity while obtaining visible light.
In 2021, wang P et al injected 1060nm and 1120nm fiber lasers into PPLN, 1060nm laser pumped PPLN to generate signal light (1627 nm) and idler light (3042 nm), 1120nm pump light and signal light (1627 nm) difference frequency to generate 3593nm idler light, the design consumed part of the signal light in the cavity, suppressed reverse conversion, and output two wavelengths of mid-infrared laser (3042 nm, 3593 nm).
One prior art scheme, as shown in FIG. 1, utilizes the sum frequency of pump generated signal light (1300-1500 nm) and pump light (1064 nm) to generate red-orange light.
As shown in FIG. 1, 1064nm pump light is generated between M1 and M3 mirrors, OPO is generated between M3 and M4, and mid-infrared laser light and red orange light are generated. Wherein, the M3 mirror has high transmission to 1064nm laser and high reflection to 1300-1500nm signal light, 580-650nm red orange light and 2.5-4.5 μm idler frequency light. M4 is high in transmission to 2.5-4.5 μm idler frequency light and 580-650nm red orange light, and high in reflection to 1300-1500nm signal light.
The wavelength of the signal light and the idler frequency light is changed by adjusting the temperature of the PPLN crystal, and red orange light with different wavelengths is obtained.
Scheme II of the prior art: the PPLN crystal is pumped at two wavelengths. As shown in FIG. 2, the M1 and M2 mirrors are highly transparent to the pump light (1-1.2 μm) and idler light (3-4 μm), and highly reflective to the signal light (1.4-1.7 μm). The pump light 1060nm laser pumps the PPLN, outputs 1627nm signal light and 3042nm idler light, and the pump light 1120nm laser and the generated 1627nm signal light generate 3593nm idler light in a differential frequency mode.
Fixing 1060nm laser energy, and obtaining middle infrared laser output with high conversion efficiency by adjusting input 1120nm laser energy.
The first scheme has the defects that the PPLN crystal is used as an optical parametric oscillation crystal to convert the pump light into the signal light and the idler frequency light and is used as a sum frequency crystal to convert the signal light and the pump light into the red orange light, so that the phase matching is difficult to achieve the compatibility of the optical parametric oscillation process and the sum frequency process, and the conversion efficiency is limited.
The second scheme has the disadvantage that two pump lights are required to work simultaneously, which increases the complexity of the system.
Disclosure of Invention
In order to solve the technical problems, the invention provides a pulse middle-far infrared laser optical parametric oscillator with low pumping threshold and high conversion efficiency, which is characterized by comprising a laser pumping source, an optical parametric resonant cavity, a plurality of parametric crystals, a frequency doubling crystal and a plurality of reflectors;
the optical parametric resonant cavity comprises a double-square resonant cavity formed by a first square resonant light path and a second square resonant light path;
the plurality of mirrors includes a first mirror M1, a second mirror M2, a third mirror M3, a fourth mirror M4, a fifth mirror M5, and a sixth mirror M6; each reflecting mirror forms a preset included angle with an optical axis passing through the optical path of the double-circuit resonant cavity; the method comprises the steps of carrying out a first treatment on the surface of the
The first reflecting mirror M1, the second reflecting mirror M2, the third reflecting mirror M3 and the fourth reflecting mirror M4 form a first back-shaped resonant light path of the optical parametric resonant cavity;
the first reflecting mirror M1, the fifth reflecting mirror M5, the sixth reflecting mirror M6 and the fourth reflecting mirror M4 form a second back-shaped resonant light path of the optical parametric resonant cavity;
the fifth reflector M5 is positioned on the optical axis extension line outside the second reflector M2, and the sixth reflector M6 is positioned on the optical axis extension line outside the third reflector M3;
the laser of the laser pumping source is injected into a first back-shaped resonant light path and a second back-shaped resonant light path through the first reflecting mirror M1, and is reflected by the second reflecting mirror M2, the third reflecting mirror M3 and the fourth reflecting mirror M4 and then transmitted out of the first back-shaped resonant light path through the first reflecting mirror M1;
simultaneously, laser is injected into a second back-shaped resonant light path through the first reflecting mirror M1, reflected by the fifth reflecting mirror M5, the sixth reflecting mirror M6 and the fourth reflecting mirror M4, and transmitted out of the first back-shaped resonant light path through the first reflecting mirror M1;
the frequency doubling crystal is placed between the second reflecting mirror M2 and the third reflecting mirror M3; or the frequency doubling crystal is placed between the fifth reflecting mirror M5 and the sixth reflecting mirror M6;
simultaneously placing the parametric crystal between the first mirror M1 and the second mirror M2 and between the third mirror M3 and the fourth mirror M4;
the fourth mirror M4 is an idler light output mirror that outputs idler light.
Further, the frequency doubling crystal is an LBO crystal; the parametric crystal is BGSe crystal or KTA crystal.
Further, the laser of the laser pumping source is Nd: YAG pulse laser, the pulse width of the laser is ns grade; the spot radius of the laser is more than or equal to 2mm.
Further, when the frequency doubling crystal is placed between the second mirror M2 and the third mirror M3, the third mirror M3 is used as a frequency doubling light output mirror for outputting frequency doubling light of the signal light;
when the frequency doubling crystal is placed between the fifth mirror M5 and the sixth mirror M6, the sixth mirror M6 serves as a frequency doubling light output mirror for outputting frequency doubling light of the signal light.
Furthermore, both optical surfaces of the frequency doubling crystal are plated with an antireflection film for the signal light and an antireflection film for the frequency doubling light.
Further, the reflective film and the transmissive film of each mirror are selected as follows:
the first reflecting mirror M1 has a laser transmittance T of more than 95% for the laser pumping source and a signal light reflectance R of more than 99%;
the transmittance T of the fourth reflecting mirror M4 to idler frequency light and frequency doubling light is more than 95%; the reflectivity R of the laser pump source and the signal light is more than 99 percent.
Further, the reflective film and the transmissive film of each mirror are selected as follows:
when the frequency doubling crystal is placed between the second reflecting mirror M2 and the third reflecting mirror M3, the transmittance T of the second reflecting mirror M2 for pump light and idler frequency light is more than 95%, and the reflectance R of the second reflecting mirror M2 for signal light is more than 99% from 1.14 mu M to 1.65 mu M;
the third reflector M3 has a frequency multiplication light transmittance T of more than 95% for the pump light, idler light and signal light; the reflectivity R of the signal light is more than 99 percent;
the fifth reflecting mirror M5 has a reflectivity R >99% for pump light and idler light;
the sixth mirror M6 has >99% for pump light and idler light reflectivity R.
Further, the reflective film and the transmissive film of each mirror are selected as follows:
when the frequency doubling crystal is placed between the fifth mirror M5 and the sixth mirror M6,
the second reflecting mirror M2 has a reflectivity R of more than 99% for pump light and idle frequency light and a transmissivity T of more than 95% for signal light;
the third reflecting mirror M3 has a reflectivity R of more than 99% for pump light and idle frequency light and a transmissivity T of more than 95% for signal light;
the fifth mirror M5 has a reflectivity R of >99% for the signal light;
the sixth mirror M6 has a reflectivity R of >99% for the signal light; the frequency multiplication light transmittance T of the signal light is more than 95 percent.
Further, the high reflectivity or high transmissivity of the reflector is provided by the mirror coating of the reflector.
Further, the predetermined included angle between each reflecting mirror and the optical axis passing through the optical path of the double-return-line resonant cavity is 45 degrees.
The method for generating the pulse middle-far infrared laser with low threshold and high conversion efficiency can not only obtain a low pumping threshold, but also inhibit the reverse conversion of pulse pumping light in time and space, thereby providing an effective method for improving the conversion efficiency of the middle-far infrared laser.
Drawings
FIG. 1 shows the sum frequency of 1300-1500nm of signal light generated by pumping in the prior art and pumping light to generate red orange light.
Fig. 2 is a prior art dual wavelength pumped PPLN crystal.
Fig. 3 is a schematic diagram of an optical parametric oscillator with a dual-loop resonant cavity according to the present invention.
Fig. 4 is a diagram showing an optical parametric oscillator structure of a dual-loop type resonant cavity according to a first embodiment of the present invention.
Fig. 5 is a diagram showing an optical parametric oscillator structure of a dual-loop type cavity resonator according to a second embodiment of the present invention.
Fig. 6 is a diagram showing an optical parametric oscillator structure of a dual-loop type cavity resonator according to a third embodiment of the present invention.
Detailed Description
The following detailed description of specific embodiments of the invention refers to the accompanying drawings.
The invention provides a pulse middle-far infrared laser optical parametric oscillator with low pumping threshold and high conversion efficiency, which is characterized by comprising a laser pumping source, an optical parametric resonant cavity, a plurality of parametric crystals, a frequency doubling crystal and a plurality of reflectors;
the optical parametric resonant cavity comprises a double-square resonant cavity formed by a first square resonant light path and a second square resonant light path;
the plurality of mirrors includes a first mirror M1, a second mirror M2, a third mirror M3, a fourth mirror M4, a fifth mirror M5, and a sixth mirror M6; each reflecting mirror forms a preset included angle with an optical axis passing through the double-circuit resonant cavity optical path;
the first reflecting mirror M1, the second reflecting mirror M2, the third reflecting mirror M3 and the fourth reflecting mirror M4 form a first back-shaped resonant light path of the optical parametric resonant cavity;
the first reflecting mirror M1, the fifth reflecting mirror M5, the sixth reflecting mirror M6 and the fourth reflecting mirror M4 form a second back-shaped resonant light path of the optical parametric resonant cavity;
the fifth reflector M5 is positioned on the optical axis extension line outside the second reflector M2, and the sixth reflector M6 is positioned on the optical axis extension line outside the third reflector M3;
the laser of the laser pumping source is injected into a first back-shaped resonant light path and a second back-shaped resonant light path through the first reflector M1, and is reflected by the second reflector M2, the third reflector M3 and the fourth reflector M4 and then transmitted out of the first back-shaped resonant light path through the first reflector M1;
simultaneously, laser is injected into a second back-shaped resonant light path through the first reflecting mirror M1, reflected by the fifth reflecting mirror M5, the sixth reflecting mirror M6 and the fourth reflecting mirror M4, and transmitted out of the first back-shaped resonant light path through the first reflecting mirror M1;
the frequency doubling crystal is placed between the second reflecting mirror M2 and the third reflecting mirror M3; or the frequency doubling crystal is placed between the fifth reflecting mirror M5 and the sixth reflecting mirror M6;
simultaneously placing the parametric crystal between the first mirror M1 and the second mirror M2 and between the third mirror M3 and the fourth mirror M4;
the fourth mirror M4 is an idler light output mirror that outputs idler light.
The invention adopts a mode of inserting a frequency doubling crystal into the double-circuit cavity to obtain the pulse middle-far infrared laser with low pumping threshold and high conversion efficiency. The pump light and the idler frequency light pass through the first back-shaped resonant light path for one time, the signal light oscillates in the second back-shaped resonant light path, the first back-shaped resonant light path is provided with nonlinear crystals for converting the pump light into the signal light and the idler frequency light, and the second back-shaped resonant light path is provided with frequency doubling crystals for doubling the frequency of the signal light. When the pumping energy is lower, the consumption of the signal light in the frequency doubling crystal is smaller, the vibration can be rapidly started, and the pumping threshold is lower; when the signal light power density is higher, a part of the signal light is frequency-doubled and converted into visible light, and the other part of the signal light continuously oscillates between the second back-shaped resonant light paths. The reverse conversion is restrained, the pump conversion efficiency is improved, and the intensity of the signal light in the OPO cavity can be judged by observing the intensity of the output visible light.
Further, the frequency doubling crystal is an LBO crystal; the parametric crystal is BGSe crystal or KTA crystal.
Further, the laser of the laser pumping source is Nd: YAG pulse laser, the pulse width of the laser is ns grade; the spot radius of the laser is more than or equal to 2mm.
As shown in fig. 3, M1, M2, M3, M4 form a first loop-shaped resonant optical path, and M1, M5, M6, M4 form a second loop-shaped resonant optical path. Nd: YAG outputs pulse laser with pulse width of 1.06 μm of several nanoseconds to several tens nanoseconds, M1 mirror has high transmission to 1064nm of pumping light and high reflection to 1.14-1.65 μm of signal light; the M2 and M3 mirrors have high reflection to the pumping light of 1064nm and the idler light of 3-17 mu M and high transmission to the signal light of 1.14-1.65 mu M; the M4 mirror has high reflection to the pumping light 1064nm and the signal light 1.14-1.65 mu M and high transmission to the idler light 3-17 mu M; m5 mirror is high in reflection of signal light of 1.14-1.65 mu M; the M6 mirror has high reflection for the signal light of 1.14-1.65 mu M and high transmission for the frequency multiplication light of 570-825 nm. The reference crystal is coated with an antireflection film, and has high transmittance to the pumping light of 1064nm, the signal light of 1.14-1.65 μm and the idler light of 3-17 μm. The frequency doubling crystal is plated with an antireflection film, and has high transmittance to signal light of 1.14-1.65 mu m and frequency doubling visible light of 570-825 nm.
At the beginning section, the ending section and the edge of the pumping light spot space of the pumping pulse time, the pumping light 1064nm generates a small amount of signal light 1.14-1.65 mu M and idler light 3-17 mu M after passing through the parametric crystal, the signal light is weaker at the moment, and the oscillation between M1, the parametric crystal, M5, the frequency doubling crystal, the M6 mirror, the parametric crystal, M4 and M1 is enhanced, the frequency doubling efficiency is low, and the signal light normally oscillates; the pump light is output through an M1 mirror; idler light is output through an M4 mirror.
At the center of the pumping pulse time and the center of the pumping spot space, a large amount of signal light 1.14-1.65 mu M and idler light 3-17 mu M are generated after the pumping light 1064nm passes through the parametric crystal, the signal light is strong at the moment, after the pumping light passes through the frequency doubling crystal, a part of the signal light is multiplied by frequency to generate visible light 570-825nm, the visible light is output through an M6 mirror, and the other part of the signal light is reflected by an M6 mirror and continuously oscillates among M1, M5, M6 and M4 mirrors. The pump light is output through an M1 mirror; idler frequency light is output through an M4 mirror; since the intensity of the signal light in the cavity is suppressed, the conversion efficiency of the pump light to the idler light is also increased.
Claims (10)
1. The pulse middle-far infrared laser optical parametric oscillator with low pumping threshold and high conversion efficiency is characterized by comprising a laser pumping source, an optical parametric resonant cavity, a plurality of parametric crystals, a frequency doubling crystal and a plurality of reflectors;
the optical parametric resonant cavity comprises a double-square resonant cavity formed by a first square resonant light path and a second square resonant light path;
the plurality of mirrors includes a first mirror (M1), a second mirror (M2), a third mirror (M3), a fourth mirror (M4), a fifth mirror (M5), and a sixth mirror (M6); each reflecting mirror forms a preset included angle with an optical axis passing through the optical path of the double-circuit resonant cavity;
the first reflecting mirror (M1), the second reflecting mirror (M2), the third reflecting mirror (M3) and the fourth reflecting mirror (M4) form the first back-shaped resonant light path of the optical parametric resonant cavity;
the first reflecting mirror (M1), the fifth reflecting mirror (M5), the sixth reflecting mirror (M6) and the fourth reflecting mirror (M4) form the second back-shaped resonant light path of the optical parametric resonant cavity;
the fifth reflecting mirror (M5) is positioned on an optical axis extension line outside the second reflecting mirror (M2), and the sixth reflecting mirror (M6) is positioned on an optical axis extension line outside the third reflecting mirror (M3);
the laser of the laser pumping source is injected into the first back-shaped resonant light path and the second back-shaped resonant light path through the first reflecting mirror (M1), and is transmitted out of the first back-shaped resonant light path through the first reflecting mirror (M1) after being reflected by the second reflecting mirror (M2), the third reflecting mirror (M3) and the fourth reflecting mirror (M4);
simultaneously, the laser is injected into the second back-shaped resonant light path through the first reflecting mirror (M1), and the first back-shaped resonant light path is transmitted out of the first back-shaped resonant light path through the first reflecting mirror (M1) after being reflected by the fifth reflecting mirror (M5), the sixth reflecting mirror (M6) and the fourth reflecting mirror (M4);
the frequency doubling crystal is placed between the second reflecting mirror (M2) and the third reflecting mirror (M3); or the frequency doubling crystal is placed between the fifth reflecting mirror (M5) and the sixth reflecting mirror (M6);
-simultaneously placing the parametric crystal between the first mirror (M1) and the second mirror (M2) and between the third mirror (M3) and the fourth mirror (M4);
the fourth mirror (M4) is an idler light output mirror that outputs idler light.
2. The optical parametric oscillator of claim 1, wherein the frequency doubling crystal is an LBO crystal; the parametric crystal is BGSe crystal or KTA crystal.
3. The optical parametric oscillator of claim 2, wherein the laser of the laser pump source is Nd: YAG pulse laser, the pulse width of the said laser is ns grade; the spot radius of the laser is more than or equal to 2mm.
4. An optical parametric oscillator as claimed in claim 1, wherein when the frequency doubling crystal is placed between the second reflecting mirror (M2) and the third reflecting mirror (M3), the third reflecting mirror (M3) is used as a frequency doubling light output mirror for outputting frequency doubling light of the signal light;
when the frequency doubling crystal is placed between the fifth mirror (M5) and the sixth mirror (M6), the sixth mirror (M6) is used as a frequency doubling light output mirror for outputting frequency doubling light of signal light.
5. The optical parametric oscillator of claim 4, wherein both optical surfaces of the frequency doubling crystal are coated with an antireflection film for the signal light and an antireflection film for the frequency doubling light.
6. The optical parametric oscillator of claim 4, wherein the reflective and transmissive films of each mirror are selected from:
the first reflecting mirror (M1) has a laser transmittance T of more than 95% for the laser pumping source and a signal light reflectance R of more than 99%;
the fourth mirror (M4) has a transmittance T >95% for the idler light and the doubled light; the reflectivity R of the laser pumping source and the signal light is more than 99 percent.
7. The optical parametric oscillator of claim 6, wherein the reflective and transmissive films of each mirror are selected from:
when the frequency doubling crystal is placed between the second mirror (M2) and the third mirror (M3):
the second mirror (M2) has a transmittance T >95% for pump light and idler light, and a reflectance R >99% for the signal light;
the third mirror (M3) has a frequency multiplication light transmittance T >95% for the pump light, the idler light and the signal light; -the signal light reflectivity R >99%;
the fifth mirror (M5) has >99% of the pump light and idler light reflectivity R;
the sixth mirror (M6) has >99% of the pump light and idler light reflectivity R.
8. The optical parametric oscillator of claim 6, wherein the reflective and transmissive films of each mirror are selected from:
when the frequency doubling crystal is placed between the fifth mirror (M5) and the sixth mirror (M6):
the second mirror (M2) has a reflectivity R >99% for pump light and idler light and a transmissivity T >95% for the signal light;
the third mirror (M3) has a reflectivity R >99% for the pump light and the idler light and a transmissivity T >95% for the signal light;
-said fifth mirror (M5) has a reflectivity R >99% for said signal light;
-said sixth mirror (M6) has a reflectivity R >99% to said signal light; the frequency multiplication light transmittance T of the signal light is more than 95 percent.
9. The optical parametric oscillator of any one of claims 6-8, wherein the high reflectivity or high transmissivity of the mirror is provided by a mirror coating of the mirror.
10. The optical parametric oscillator of claim 1, wherein the predetermined angle between each of the mirrors and the optical axis passing through the optical path of the dual-return-type resonant cavity is 45 degrees.
Priority Applications (1)
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| WO1998001927A1 (en) * | 1996-07-04 | 1998-01-15 | The Secretary Of State For Defence | Optical parametric oscillator |
| CN102751653A (en) * | 2012-07-19 | 2012-10-24 | 厦门大学 | Photonic crystal fiber based medium-infrared optical fiber parametric oscillator for degenerating four-wave mixing |
| CN110556699A (en) * | 2019-09-16 | 2019-12-10 | 西安电子科技大学 | High-energy high-light beam quality tunable optical parametric oscillator pumped by nanosecond laser |
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| US7130321B2 (en) * | 2003-10-09 | 2006-10-31 | Coherent, Inc. | Intracavity frequency-tripled CW laser with traveling-wave ring-resonator |
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| WO1998001927A1 (en) * | 1996-07-04 | 1998-01-15 | The Secretary Of State For Defence | Optical parametric oscillator |
| CN102751653A (en) * | 2012-07-19 | 2012-10-24 | 厦门大学 | Photonic crystal fiber based medium-infrared optical fiber parametric oscillator for degenerating four-wave mixing |
| CN110556699A (en) * | 2019-09-16 | 2019-12-10 | 西安电子科技大学 | High-energy high-light beam quality tunable optical parametric oscillator pumped by nanosecond laser |
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