CN114614332A - Non-resonant ring collision frequency doubling device - Google Patents

Non-resonant ring collision frequency doubling device Download PDF

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Publication number
CN114614332A
CN114614332A CN202210189949.5A CN202210189949A CN114614332A CN 114614332 A CN114614332 A CN 114614332A CN 202210189949 A CN202210189949 A CN 202210189949A CN 114614332 A CN114614332 A CN 114614332A
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China
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frequency doubling
light
resonant ring
laser
resonant
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CN202210189949.5A
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Chinese (zh)
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汪中
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Wenzhou Laser And Photoelectronics Co Innovation Center
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Wenzhou Laser And Photoelectronics Co Innovation Center
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Priority to CN202210189949.5A priority Critical patent/CN114614332A/en
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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
    • H01S3/10—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
    • H01S3/109—Frequency multiplication, e.g. harmonic generation
    • 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
    • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H01S3/101—Lasers provided with means to change the location from which, or the direction in which, laser radiation is emitted
    • 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
    • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H01S3/105—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling the mutual position or the reflecting properties of the reflectors of the cavity, e.g. by controlling the cavity length
    • 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
    • H01S3/10—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

Abstract

The invention relates to a non-resonant ring colliding frequency doubling device, which is characterized in that: and a non-resonant ring is added in the laser resonant cavity to realize the intra-cavity frequency doubling, or the laser enters the non-resonant ring device after being output to realize the out-cavity colliding frequency doubling. The light pulses are transmitted in the non-resonant ring in opposite directions and collide in the frequency doubling crystal to realize coherence, the standing wave can enhance the intensity of an antinode light field, and meanwhile, the light waist is positioned at the pulse collision position to maximize the local light intensity; and the frequency doubling efficiency is in direct proportion to the square of the light intensity, so that the frequency doubling efficiency can be effectively improved. The non-resonant ring cavity inner and outer colliding frequency doubling device disclosed by the scheme can obviously improve the light intensity in the frequency doubling crystal, thereby realizing more effective laser frequency doubling.

Description

Non-resonant ring colliding frequency doubling device
Technical Field
The invention belongs to the field of laser and laser frequency doubling, and provides a non-resonant ring cavity inner and outer colliding frequency doubling device.
Background
Laser frequency doubling is a key technology for converting laser to higher frequency, is a very widely applied technology, enriches frequency components output by the laser, and enlarges the application scene of the laser. The laser frequency doubling scheme is various, and has intracavity frequency doubling and extracavity frequency doubling, and output laser can be coupled into a resonant cavity which is independently used for frequency doubling to improve the frequency doubling efficiency. However, a resonant cavity dedicated for frequency doubling is generally added, and the coupling efficiency is not high due to the reflectivity of the input cavity mirror, so that the frequency doubling efficiency is affected. If the mode-locking pulse is frequency-doubled during intracavity frequency doubling, the pulses pass through in a reciprocating and unidirectional mode, and the interference enhancement can not be achieved when the pulse peak passes through and the opposite pulses meet in the frequency-doubled crystal.
The present invention is an improvement in view of the above problems.
Disclosure of Invention
The invention provides a non-resonant ring colliding frequency doubling device which can be used for frequency doubling of laser, further improves the frequency doubling efficiency of the laser and solves the problems existing in the use process in the prior art.
The technical scheme of the invention is realized as follows:
non-resonant ring colliding frequency doubling device, its characterized in that: the laser resonant cavity is added with a non-resonant ring or enters the non-resonant ring after laser output, so that optical pulses are transmitted in the ring in opposite directions and collide in a frequency doubling crystal to realize coherence, standing waves can strengthen the intensity of an antinode optical field, and meanwhile, the design of the laser resonant cavity and the non-resonant ring enables an optical waist to be positioned at the pulse collision position to maximize the local light intensity; and the frequency doubling efficiency is in direct proportion to the square of the light intensity, so that the frequency doubling efficiency is effectively improved.
Preferably, the non-resonant ring clash pulse frequency doubling can be used for a frequency doubling device after the output of the laser and can also be used for frequency doubling in a laser resonant cavity, so that the non-resonant ring becomes a part of the resonant cavity.
Preferably, the frequency doubling in the laser resonant cavity comprises a reflector R1, a laser gain medium and a non-resonant ring, wherein the non-resonant ring consists of a reflector R2, a reflector R3 and a spectroscope S, light paths of two opposite transmitted light beams after light splitting are in the same direction and opposite directions, and the two opposite transmitted light beams return to the spectroscope and then are coupled back to the incident direction of the laser resonant cavity through interference; a frequency doubling crystal is placed at a pulse collision point which is equidistant from the spectroscope in the non-resonant ring and is also a light waist position; the frequency doubling light is coupled back into the laser resonant cavity by the spectroscope S and then is output by the optical filter D.
Preferably, the non-resonant ring of the frequency doubling device outside the cavity consists of two concave mirrors, a frequency doubling crystal and a 50% spectroscope, and the concave mirrors are designed and adjusted to enable the laser waist to be just positioned at a pulse collision point, namely, the optical paths of the light pulse reaching the point through the spectroscope are the same.
As a preferred option, the frequency doubling crystal is placed at the pulse collision point which is also the light waist position, so that the interference of a local light field is enhanced, and the frequency doubling efficiency is improved due to high light intensity.
Preferably, an optical isolator is arranged between the laser and the non-resonant ring during frequency doubling outside the cavity to prevent the fundamental frequency light from returning to the laser.
Preferably, the reflector R1 in the intracavity frequency doubling device is a total reflection mirror.
Preferably, the intracavity frequency doubling device S is a 50% beam splitter.
Preferably, the filter D in the intracavity frequency doubling device is an interference filter which functions to reflect the frequency doubled light and transmit the fundamental light.
In summary, the technical solutions are further described as follows:
the frequency doubling device used after the output of the laser comprises: the non-resonant ring structure is shown in fig. 1 as part of the dashed box. S is a 50% spectroscope, the laser beam is divided into two beams with equal intensity after the beam splitter, the two beams are respectively transmitted along opposite directions, and the two beams collide in a frequency doubling crystal B after passing through two reflectors of a reflector R4 and a reflector R5 to form a standing wave field. In addition, the two mirrors R4 and R5 in the non-resonant ring should be designed as concave mirrors according to the input light parameters, so that the light waist of the gaussian beam is at the position of the frequency doubling crystal B to further increase the local optical field intensity.
After frequency multiplication, the fundamental frequency light and the frequency multiplication light continue to propagate along the opposite direction of the light path, return to the spectroscope, and are coupled to the direction opposite to the incident light to be output from the non-resonant ring due to the fact that the light paths are identical and the reverse interference of the incident surface is strengthened. At this time, an interference filter D is placed on the light path to reflect the frequency-doubled light and pass the fundamental light. The frequency-doubled light is output by reflection, and the fundamental light returns to the laser resonant cavity along the original optical path.
If the interference of reflected light to the original mode-locked laser is required to be avoided in the frequency doubling device outside the cavity, an optical isolator can be placed after laser output to prevent the fundamental frequency light from returning to the laser.
When the non-resonant ring is used for frequency doubling in the laser resonant cavity: the structure is shown in FIG. 2, and a non-resonant ring laser resonator is formed by the mirror R1, the mirror R2, the mirror R3 and the beam splitter S. If passive mode locking is needed, two reflectors R2 and R3 are designed as concave mirrors, at this time, the laser beam has two light waists in the resonant cavity, one is present at the midpoint of the connecting line of R2 and R3, and the other is at the reflector R1, the positions of components in the cavity can be designed according to different mode locking matrixes, and the frequency doubling crystal is placed at the midpoint of the non-resonant ring, so that the result of improving the frequency doubling efficiency can be obtained. R1 is an interference filter which is highly reflective to fundamental light and transmissive to frequency doubled light, and the frequency doubled light is directly output from the mirror R1. It is of course also possible to design the mirror R1 as a concave mirror so that another light waist appears between the beam splitter S and the mirror R1. R1 may also be designed as a high-reflectivity mirror. And an interference filter D is inserted into the cavity, so that the frequency doubling light is reflected and output by the D.
In conclusion, the beneficial effects of the invention are as follows:
the non-resonant ring clash frequency doubling device disclosed by the scheme has the advantages that the light intensity in the frequency doubling crystal is obviously improved, the frequency doubling efficiency is greatly improved, and more effective laser frequency doubling is realized.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a schematic diagram of an external cavity colliding frequency doubling device for frequency doubling after laser output enters a non-resonant ring.
FIG. 2 is a schematic diagram of the non-resonant ring frequency doubling in the laser resonator according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to fig. 1-2 in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of protection of the present invention.
Example 1
The invention discloses a non-resonant ring clash frequency doubling device, wherein the non-resonant ring clash frequency doubling device is shown in figure 1 after the output of a laser, fundamental frequency light firstly passes through an interference filter D after being output from the laser, and the interference filter D transmits the fundamental frequency light and reflects frequency doubling light. Then the fundamental frequency light reaches the non-resonant ring system, is divided into two beams of light which have the same light intensity and are transmitted along the opposite direction by the spectroscope S, and forms a light waist in the frequency doubling crystal B by the two concave reflectors of the reflector R4 and the reflector R5. Meanwhile, because the light pulses collide in the frequency doubling crystal, the intensity of a local light field is further enhanced, and the frequency doubling efficiency is further improved. The frequency doubling light is continuously transmitted along the light path and meets the light splitter S, because the light paths of the two light beams transmitted along the opposite directions are identical, the two light beams are coupled to the incident light direction through interference and return to the laser direction, and after reaching the interference filter D, the frequency doubling light is reflected and output, and the fundamental frequency light passes through. In this case, if it is not desired that the fundamental light be returned to the laser to affect laser operation, an optical isolator E may be added between the interference filter D and the laser. The embodiment is used for the optimal frequency doubling effect of ultrashort pulses, and can also be used for frequency doubling of common Q-switched pulse lasers or even continuous lasers.
Example 2
The whole laser system is shown in figure 2, the resonant cavity R1 is a plane mirror, the gain medium LM and the active or passive mode locking device of the laser, or the Q adjusting device, can be arranged near R1, the non-resonant ring is arranged at one side of the resonant cavity, the laser beam enters the non-resonant ring and then is divided into two beams of light transmitted in opposite directions by the spectroscope S, the light waist is formed inside the frequency doubling crystal B through the two concave mirrors R2 and R3, the light intensity is maximum, and because the light path reaching the frequency doubling crystal B after light division is the same, the light pulse forms standing wave interference enhancement inside the frequency doubling crystal B, and the frequency doubling efficiency is further improved. Then the frequency doubling light is coupled back to the original direction through the spectroscope S, at the moment, an interference filter D can be added into the light path to reflect and output the frequency doubling light, and the fundamental frequency light returns to the gain medium for further gain amplification. If the laser gain medium is transparent to the frequency-doubled light, the interference filter D can be omitted, and the frequency-doubled light can be output from R1. R1 may be designed to be highly reflective to fundamental light and transmissive to frequency doubled light. The design forms the frequency doubling in the resonant cavity of the non-resonant ring. The non-resonant ring can also be combined with a fiber laser or other lasers to form an intracavity non-resonant ring frequency doubling system.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (9)

1. Non-resonant ring colliding frequency doubling device, its characterized in that: the laser resonant cavity or the output light enters a non-resonant ring, so that light pulses are transmitted in the ring in opposite directions and collide in a frequency doubling crystal to realize coherence, standing waves can enhance the intensity of an antinode light field, and meanwhile, the design of the laser resonant cavity and the non-resonant ring enables a light waist to be positioned at the pulse collision position to maximize the local light intensity; and the frequency doubling efficiency is in direct proportion to the square of the light intensity, so that the frequency doubling efficiency can be effectively improved.
2. The non-resonant ring frequency-doubling device according to claim 1, wherein: the non-resonant ring colliding pulse frequency doubling can be used for a frequency doubling device after the output of a laser and can also be used for frequency doubling in a laser resonant cavity, so that the non-resonant ring becomes a part of the resonant cavity.
3. The non-resonant ring frequency-doubling device according to claim 2, wherein: the frequency doubling in the laser resonant cavity comprises a reflector R1, a laser gain medium and a non-resonant ring, wherein the non-resonant ring consists of a reflector R2, a reflector R3 and a spectroscope S, two paths of light beam light paths transmitted in opposite directions after light splitting are identical, and interference coupling is returned to the incident direction of the laser resonant cavity after returning to the spectroscope; a frequency doubling crystal is placed at a pulse collision point which is equidistant from the spectroscope in the non-resonant ring and is also a light waist position; the frequency doubling light is coupled back into the laser resonant cavity through the spectroscope of the input mirror S and then is output through the optical filter D.
4. The non-resonant ring frequency-doubling device according to claim 2, wherein: the non-resonant ring of the frequency doubling device consists of two concave mirrors, a frequency doubling crystal and a 50% spectroscope, wherein the concave mirrors are designed and adjusted to ensure that the non-resonant inner light waist is just positioned at a pulse collision point, namely the optical paths of light pulses reaching the point through the spectroscope are the same.
5. The non-resonant ring colliding frequency doubling device as recited in claim 4, wherein: the frequency doubling crystal is placed at the pulse collision point and is also the light waist position, so that the interference of a local light field is enhanced, and the frequency doubling efficiency is improved due to high light intensity.
6. The non-resonant ring colliding frequency doubling device as recited in claim 4, wherein: an optical isolator is arranged behind the laser output to prevent the fundamental frequency light from returning to the laser.
7. The non-resonant ring colliding frequency doubling device as recited in claim 3, wherein: the reflector R1 is a total reflection mirror.
8. The non-resonant ring cavity colliding frequency doubling device according to claim 3, wherein: s is a 50% spectroscope.
9. The non-resonant ring intracavity collisional frequency doubling device of claim 3 or 8, wherein: the filter D is an interference filter, and functions to reflect the frequency-doubled light and transmit the fundamental light.
CN202210189949.5A 2022-02-28 2022-02-28 Non-resonant ring collision frequency doubling device Pending CN114614332A (en)

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Application Number Priority Date Filing Date Title
CN202210189949.5A CN114614332A (en) 2022-02-28 2022-02-28 Non-resonant ring collision frequency doubling device

Publications (1)

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CN114614332A true CN114614332A (en) 2022-06-10

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