A triple frequency laser generation system

Abstract

The present invention discloses a triple frequency laser generation system, comprising a laser emission module, a spatial isolator, a frequency doubling module, and a sum frequency module. The laser emission module comprises a single frequency laser, a phase modulator, and a laser amplification module connected in sequence. The laser emission module also comprises a signal generator, which generates a radio frequency signal to drive the phase modulator to perform phase modulation on the single frequency laser output by the single frequency laser. The phase modulation amplitude is 2 N π / 3±π / 10, where N is an integer. The present invention applies phase modulation to a single-frequency seed laser and controls the phase modulation depth, suppressing nonlinear effects in the amplifier to achieve high-power fundamental frequency light output and frequency up-conversion. Ultimately, single-frequency or narrow-linewidth high-power tripled frequency laser output is achieved, solving the problem of achieving both high power and narrow linewidth simultaneously.

Description

Technical Field

[0001] The present invention relates to the field of laser technology, in particular to a frequency tripled laser generating system. Background Art

[0002] Single-frequency or narrow-linewidth visible and ultraviolet lasers have a wide range of applications in precision machining, atomic cooling, biomedicine, and other fields. Nonlinear optical frequency up-conversion of near-infrared lasers is an important means of obtaining high-power lasers in this band. In the process of obtaining visible and ultraviolet lasers through nonlinear optical frequency conversion, increasing the fundamental frequency light power is an important way to achieve efficient frequency conversion. However, as the fundamental frequency light power increases, various nonlinear effects will appear in amplifiers, especially fiber amplifiers. In particular, stimulated Brillouin scattering greatly limits the output power of laser amplifiers. To suppress the nonlinear effects in amplifiers, spectral broadening is usually used to reduce the power spectrum density to achieve high-power fundamental frequency light output. However, this will result in the fundamental frequency light used for frequency up-conversion no longer being a single-frequency or narrow-linewidth laser. Instead, the linewidth will be further widened after frequency up-conversion, making it impossible to obtain single-frequency or narrow-linewidth visible and ultraviolet lasers. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the present invention proposes a triple frequency laser generation system. By applying phase modulation to the fundamental frequency light before amplification, the single frequency laser can obtain a debugging depth of 2 N π / 3±π / 10 (where N The amplified laser undergoes a single frequency doubling and a single sum frequency conversion to produce a high-power single-frequency or narrow-linewidth tripled frequency laser with a phase modulation depth near 0 and an integer multiple of 2π.

[0004] The specific technical solutions of the present invention are as follows:

[0005] A triple frequency laser generation system includes a laser emission module, a spatial isolator, a frequency doubling module, and a sum frequency module arranged in sequence. The laser emission module includes a single frequency laser, a phase modulator, and a laser amplification module connected in sequence. The laser emission module also includes a signal generator. The signal generator generates a radio frequency signal to drive the phase modulator to phase modulate the single frequency laser output by the single frequency laser. The phase modulation amplitude is 2 N π / 3±π / 10, where N is an integer; after the single-frequency laser passes through the phase modulator, it enters the laser amplifier for amplification, and then passes through the spatial isolator, the frequency doubling module and the sum frequency module in sequence to obtain a single-frequency or narrow-linewidth tripled frequency laser with a phase modulation amplitude of 0 and an integer multiple of 2π.

[0006] Furthermore, the single-frequency laser is one of a rare earth-doped solid laser, a solid Raman laser, a distributed feedback semiconductor laser, an external cavity semiconductor laser, a distributed feedback fiber laser, and a distributed Bragg reflection fiber laser, and the linewidth of the generated single-frequency laser is less than 200 MHz.

[0007] Furthermore, the phase modulator is an electro-optical phase modulator with a fiber tail or a spatial electro-optical phase modulator.

[0008] Furthermore, the phase-modulated driving signal of the signal generator is one of a pulse signal, a square wave signal, a pseudo-random code signal, and any signal whose amplitude changes in a step-like manner over time.

[0009] Furthermore, the laser amplifier used in the laser amplification module is one of a rare-earth-doped fiber amplifier, a fiber Raman amplifier, a rare-earth-doped solid amplifier, and a solid Raman amplifier.

[0010] Furthermore, the frequency doubling module adopts one of single-pass frequency doubling, double-pass frequency doubling, single-pass cascade frequency doubling, and external cavity resonance frequency doubling; the frequency doubling crystals used in the frequency doubling module are: periodically poled lithium niobate, periodically poled stoichiometric lithium tantalate, periodically poled potassium titanyl phosphate crystal, β - One of barium metaborate crystals, lithium triborate crystals, bismuth borate crystals, lithium cesium borate crystals, potassium titanyl phosphate crystals, potassium dihydrogen phosphate crystals, potassium dideuterium phosphate crystals, ammonium dihydrogen phosphate, dideuterium ammonium phosphate crystals, guanidine tetrafluoroborate crystals, and calcium yttrium oxyborate crystals.

[0011] Furthermore, the sum frequency module adopts one of single-pass sum frequency, double-pass sum frequency, cascaded single-pass sum frequency, and external cavity resonance sum frequency; the sum frequency crystals used in the sum frequency module are: periodically poled lithium niobate, periodically poled stoichiometric lithium tantalate, periodically poled potassium titanyl phosphate crystal, β - One of barium metaborate crystal, lithium triborate crystal, bismuth borate crystal, lithium cesium borate crystal, potassium titanyl phosphate crystal, potassium dihydrogen phosphate crystal, potassium dideuterium phosphate crystal, potassium dihydrogen phosphate crystal, guanidine tetrafluoroborate crystal, potassium fluoroborate, quartz crystal with additional periodic phase, potassium dihydrogen phosphate crystal with additional periodic phase, potassium dideuterium phosphate crystal with additional periodic phase, dihydrogen phosphate crystal with additional periodic phase, and dideuterium ammonium phosphate crystal with additional periodic phase.

[0012] Furthermore, the temperature control of the frequency doubling module and the sum frequency module adopts a heating plate or a semiconductor cooling plate, and the temperature control accuracy is less than or equal to 0.02 degrees Celsius.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] By applying phase modulation to a single-frequency seed laser and controlling the phase modulation depth, the present invention achieves high-power fundamental frequency optical output and frequency up-conversion by suppressing nonlinear effects in the amplifier. Ultimately, single-frequency or narrow-linewidth high-power tripled frequency laser output is achieved, resolving the difficulty of simultaneously achieving both high power and narrow linewidth. Furthermore, the frequency up-conversion process is utilized to passively demodulate the applied phase modulation, eliminating the need for a complex active demodulation system and simplifying the device. This invention provides a new technical approach for stable high-power single-frequency or narrow-linewidth frequency up-conversion technology, possessing significant practical value and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 A schematic diagram of a frequency tripled laser generation system provided by the present invention;

[0017] Figure 2 A schematic structural diagram of the frequency multiplication module provided by the present invention;

[0018] Figure 3 This is a structural diagram of the sum frequency module provided by the present invention. DETAILED DESCRIPTION

[0019] The present invention will be described in further detail below with reference to the accompanying drawings.

[0020] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0021] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0022] In order to further improve the output power and stability of single-frequency or narrow-linewidth visible and ultraviolet lasers in the existing technology, the present invention proposes a triple frequency laser generation system.N π / 3±π / 10 (where N is an integer), suppressing nonlinear effects such as stimulated Brillouin scattering during the amplification process to obtain high-power fundamental frequency light. Thereafter, after a single frequency doubling and a single sum frequency process, the frequency is up-converted while passively demodulating the applied phase modulation, ultimately generating a high-power tripled frequency single-frequency or narrow-linewidth laser with a phase modulation depth of 0 and an integer multiple of 2π.

[0023] An embodiment for implementing the above method is given below.

[0024] Example 1: Please refer to Figure 1-Figure 3 A triple frequency laser generation system includes a laser emission module, a spatial isolator 5, a frequency doubling module 6, and a sum frequency module 7, which are arranged in sequence. The laser emission module includes a single-frequency laser 1, a phase modulator 2, and a laser amplification module 4 connected in sequence through optical fibers. The laser emission module also includes a signal generator 3, which is connected to the phase modulator 2 through a radio frequency line. The signal generator 3 generates a radio frequency signal to drive the phase modulator 2 to phase modulate the single-frequency laser output by the single-frequency laser 1. The phase modulation amplitude is 2 N π / 3±π / 10, where N After passing through the phase modulator 2, the single-frequency laser enters the laser amplifier 4 for amplification. It then passes through the spatial isolator 5, the frequency doubling module 6, and the sum frequency module 7 in sequence to obtain a single-frequency or narrow-linewidth tripled frequency laser with a phase modulation amplitude near 0 and an integer multiple of 2π.

[0025] The single-frequency laser 1 is a single-frequency distributed feedback semiconductor laser with a linewidth of 1 MHz and a central wavelength of 1064 nm. The phase modulator 2 is a lithium niobate electro-optical modulator with a pigtail. The signal generator 3 generates a periodic square wave signal to drive the phase modulator 2. The driving signal frequency is 3.5 GHz and the amplitude is 10 V; The laser amplification module 4 uses ytterbium-doped fiber as the gain fiber of the laser amplifier. The frequency doubling module 6 is a single-pass frequency doubling device. The frequency doubling module 6 includes a first optical lens 6.1, a frequency doubling crystal 6.2, and a second optical lens 6.3 arranged in sequence. The frequency doubling crystal 6.2 is a periodically poled lithium niobate crystal (PPLN). The frequency doubling module 6 uses a semiconductor refrigeration plate for temperature control with an accuracy of 0.002 degrees Celsius. The sum frequency module 7 adopts a single-pass sum frequency method, which includes a third optical lens 7.1, a sum frequency crystal 7.2, and a fourth optical lens 7.3 arranged in sequence. The sum frequency crystal 7.2 is a lithium triborate crystal (LBO). The sum frequency module 7 uses a TEC for temperature control with an accuracy of 0.002 degrees Celsius.

[0026] Example 2: Please refer to Figure 1-Figure 3A triple frequency laser generation system includes a laser emission module, a spatial isolator 5, a frequency doubling module 6, and a sum frequency module 7, which are arranged in sequence. The laser emission module includes a single-frequency laser 1, a phase modulator 2, and a laser amplification module 4 connected in sequence through optical fibers. The laser emission module also includes a signal generator 3, which is connected to the phase modulator 2 through a radio frequency line. The signal generator 3 generates a radio frequency signal to drive the phase modulator 2 to phase modulate the single-frequency laser output by the single-frequency laser 1. The phase modulation amplitude is 2 N π / 3±π / 10, where N After passing through the phase modulator 2, the single-frequency laser enters the laser amplifier 4 for amplification. It then passes through the spatial isolator 5, the frequency doubling module 6, and the sum frequency module 7 in sequence to obtain a single-frequency or narrow-linewidth tripled frequency laser with a phase modulation amplitude near 0 and an integer multiple of 2π.

[0027] The single-frequency laser 1 is a single-frequency external cavity semiconductor laser with a linewidth of 120 MHz and a central wavelength of 1178 nm. The phase modulator 2 is an electro-optical modulator with a pigtail. The signal generator 3 generates a pseudo-random code signal to drive the phase modulator 2. The driving signal code rate is 2 Gbps, amplitude 12V; laser amplification module 4 is a fiber Raman laser amplifier, using phosphorus-doped fiber as the gain fiber; frequency doubling module 6 is a single-pass frequency doubling device, which includes a first optical lens 6.1, a frequency doubling crystal 6.2, and a second optical lens 6.3 arranged in sequence. The frequency doubling crystal 6.2 is a lithium triborate crystal (LBO) and is temperature-controlled by a heater with an accuracy of 0.02 degrees Celsius. The sum frequency module 7 uses an external cavity resonant sum frequency method of frequency doubling optical resonance. The sum frequency module 7 includes an input and output coupling cavity mirror 7.1, a sum frequency crystal 7.2, and a digital locked cavity servo system 7.3 arranged in sequence. The sum frequency crystal 7.2 is a lithium cesium borate crystal (CLBO) and is temperature-controlled by a heater with an accuracy of 0.02 degrees Celsius.

[0028] The above description is only a preferred embodiment of the present invention. Although the present invention has been disclosed as a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can use the above disclosed methods and technical contents to make many possible changes and modifications to the technical solution of the present invention without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment with equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A triple frequency laser generation system, comprising a laser emission module, a spatial isolator (5), a frequency doubling module (6), and a sum frequency module (7) arranged in sequence, wherein the laser emission module comprises a single frequency laser (1), a phase modulator (2), and a laser amplification module (4) connected in sequence, characterized in that: The laser emission module further comprises a signal generator (3), which generates a radio frequency signal to drive a phase modulator (2) to perform phase modulation on the single-frequency laser output by the single-frequency laser (1), and the phase modulation amplitude is 2 N π / 3±π / 10, where N is an integer; after the single-frequency laser passes through the phase modulator (2), it enters the laser amplification module (4) for amplification, and then passes through the spatial isolator (5), the frequency doubling module (6) and the sum frequency module (7) in sequence to obtain a single-frequency or narrow-linewidth tripled frequency laser with a phase modulation amplitude of 0 and an integer multiple of 2π.

2. A frequency tripled laser generating system according to claim 1, characterized in that: The single-frequency laser (1) is one of a rare earth doped solid laser, a solid Raman laser, a distributed feedback semiconductor laser, an external cavity semiconductor laser, a distributed feedback fiber laser, and a distributed Bragg reflection fiber laser, and the line width of the generated single-frequency laser is less than 200 MHz.

3. A frequency tripled laser generating system according to claim 1, characterized in that: The phase modulator (2) is an electro-optical phase modulator with a fiber tail or a spatial electro-optical phase modulator.

4. A frequency tripled laser generating system as claimed in claim 1, characterized in that: The phase-modulated driving signal of the signal generator (3) is one of a pulse signal, a square wave signal, a pseudo-random code signal, and any signal whose amplitude changes in a step-like manner over time.

5. The triple frequency laser generating system according to claim 1, wherein: The laser amplifier used in the laser amplification module (4) is one of a rare earth doped optical fiber amplifier, an optical fiber Raman amplifier, a rare earth doped solid amplifier, and a solid Raman amplifier.

6. The triple frequency laser generating system according to claim 1, wherein: The frequency doubling module (6) adopts one of single-pass frequency doubling, double-pass frequency doubling, single-pass cascade frequency doubling, and external cavity resonance frequency doubling; the frequency doubling crystals used in the frequency doubling module (6) are: periodically poled lithium niobate, periodically poled stoichiometric lithium tantalate, periodically poled potassium titanyl phosphate crystal, β - One of barium metaborate crystals, lithium triborate crystals, bismuth borate crystals, lithium cesium borate crystals, potassium titanyl phosphate crystals, potassium dihydrogen phosphate crystals, potassium dideuterium phosphate crystals, ammonium dihydrogen phosphate, dideuterium ammonium phosphate crystals, guanidine tetrafluoroborate crystals, and calcium yttrium oxyborate crystals.

7. The triple frequency laser generating system according to claim 1, wherein: The sum frequency module (7) adopts one of single-pass sum frequency, double-pass sum frequency, cascade single-pass sum frequency, and external cavity resonance sum frequency; the sum frequency crystals used in the sum frequency module (7) are: periodically poled lithium niobate, periodically poled stoichiometric lithium tantalate, periodically poled potassium titanyl phosphate crystal, β - One of barium metaborate crystal, lithium triborate crystal, bismuth borate crystal, lithium cesium borate crystal, potassium titanyl phosphate crystal, potassium dihydrogen phosphate crystal, potassium dideuterium phosphate crystal, potassium dihydrogen phosphate crystal, guanidine tetrafluoroborate crystal, potassium fluoroborate, quartz crystal with additional periodic phase, potassium dihydrogen phosphate crystal with additional periodic phase, potassium dideuterium phosphate crystal with additional periodic phase, dihydrogen phosphate crystal with additional periodic phase, and dideuterium ammonium phosphate crystal with additional periodic phase.

8. The triple frequency laser generating system according to claim 1, wherein: The temperature control of the frequency doubling module (6) and the sum frequency module (7) uses a heating plate or a semiconductor cooling plate, and the temperature control accuracy is less than or equal to 0.02 degrees Celsius.

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