Ultraviolet optical fiber optical parametric oscillator based on tunable picosecond green light

Abstract

The utility model discloses an ultraviolet optical fiber optical parametric oscillator based on tunable picosecond green light. The ultraviolet optical fiber optical parametric oscillator comprises a high-power wavelength and repetition frequency adjustable 1 [mu] m laser system, a high-power second harmonic generation device and an optical fiber optical parametric oscillator, the high-power wavelength and repetition frequency adjustable 1 [mu] m laser system comprises a mode-locked fiber laser, a pulse stretcher, an adjustable fiber filter, a fiber pre-amplifier, a fiber collimator and a solid amplifier. According to the utility model, the wavelength of ultraviolet laser can be flexibly adjusted; through a narrow-band filtering technology, the generation efficiency of the ultraviolet laser is improved; an optical parametric oscillator based on a nonlinear optical fiber is designed, a more compact resonant cavity structure is realized, the influence of a heat effect on system efficiency and stability is inhibited, and ultraviolet laser with an excellent light spot mode can be output; the dispersion parameter of the nonlinear optical fiber can be regulated and controlled, so that the phase matching condition of four-wave mixing is optimized, and the efficiency and wavelength tuning range of ultraviolet laser are further improved.

Description

Technical Field

[0001] This utility model relates to the field of oscillator technology, specifically to an ultraviolet fiber optical parametric oscillator based on tunable picosecond green light. Background Technology

[0002] High-repetition-rate ultraviolet ultrafast laser sources with tunable wavelengths have significant application value in fields such as quantum optics, optical data storage, atmospheric remote sensing, combustion diagnostics, precision micromachining, and biomedicine and life sciences. The existing technologies capable of generating ultraviolet light sources mainly include the following:

[0003] (1) Ultraviolet laser radiation is generated based on excimer lasers. However, such lasers are large in size, complex in system, and have very limited wavelength adjustment capabilities, making it difficult to directly generate ultrafast lasers.

[0004] (2) Cerium doping (Ce) 3+ Fluoride lasers are a potential candidate for tunable ultraviolet lasers, but they require deep ultraviolet laser pumping. Such pump sources are usually obtained by multi-level harmonic conversion of near-infrared solid-state lasers, which has low conversion efficiency.

[0005] (3) Nonlinear optical frequency conversion technology provides a new option for realizing high-repetition-rate wavelength tunable ultraviolet ultrafast lasers. This type of frequency conversion technology can be mainly divided into two types: optical frequency doubling technology and optical parametric oscillation technology. Taking optical frequency doubling as an example, the mainstream technique is to generate green light by frequency doubling a high-power, high-repetition-rate Yb ultrafast fiber laser, and then the green light is further frequency-doubled or combined with a 1μm laser emitted by the Yb fiber laser to generate ultraviolet laser. However, the conversion efficiency of these two methods is usually low, and a high-power fundamental frequency light is required to obtain usable ultraviolet laser, which increases the complexity and energy consumption of the system. Optical parametric oscillation technology is an effective means to realize tunable ultraviolet ultrafast laser output with a wide spectral range. Current technologies mainly rely on solid-state optical parametric oscillators (SPOs) to generate ultraviolet lasers. However, this technology faces several drawbacks. First, the construction of an all-solid-state optical resonator involves complex mirror alignment and mode matching. Since the cavity length is related to the pump laser repetition rate, a resonator length of several meters is required for pulses of tens of MHz, which greatly increases the spatial volume of the laser. Second, for spatial resonator structures, the output beam pattern is easily degraded due to mirror misalignment and thermal effects. These problems limit the application of all-solid-state optical parametric resonators to some extent. Utility Model Content

[0006] The purpose of this invention is to provide an ultraviolet fiber optical parametric oscillator based on tunable picosecond green light to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, this utility model provides the following technical solution: an ultraviolet fiber optical parametric oscillator based on tunable picosecond green light, comprising a high-power wavelength and repetition rate tunable 1μm laser system, a high-power second harmonic generation device, and a fiber optical parametric oscillator.

[0008] The high-power, wavelength- and repetition-rate-tunable 1μm laser system includes a mode-locked fiber laser, a pulse stretcher, a tunable fiber filter, a fiber preamplifier, a fiber collimator, and a solid-state amplifier, wherein the mode-locked fiber laser, pulse stretcher, tunable fiber filter, fiber preamplifier, fiber collimator, and solid-state multi-pass or regenerative amplifier are connected in sequence.

[0009] The solid-state amplifier receives the signal light output from the fiber collimator and further amplifies the signal light power to tens of watts. The amplified signal light is then injected into a high-power second harmonic generation device composed of a nonlinear optical crystal.

[0010] The fiber optic parametric oscillator includes a nonlinear fiber, an optical delay line, and an optical cavity mirror.

[0011] Preferably, the solid-state amplifier includes a solid-state multi-pass amplifier and a solid-state regenerative amplifier.

[0012] Preferably, the optical cavity mirror includes a dichroic mirror, a total reflection mirror, and an output mirror.

[0013] Preferably, the operating bandwidth of the tunable fiber optic filter is <1nm.

[0014] Preferably, the high-power picosecond green light, acting as a pump, is transmitted through a dichroic mirror and coupled into a nonlinear optical fiber. The ultraviolet laser generated by the four-wave mixing effect excited by the picosecond green light is produced in the nonlinear optical fiber and forms a stable resonance in a resonant cavity composed of an optical delay line, a dichroic mirror, a nonlinear optical fiber, a total reflection mirror, and an output mirror. Part of the energy is then output through the output mirror.

[0015] Compared with the prior art, the beneficial effects of this utility model are:

[0016] (1) In terms of system structure, the optical parametric resonator based on nonlinear fiber can achieve a more compact spatial structure compared with the all-solid resonator, and does not require complex mode matching. At the same time, due to the waveguide structure of the nonlinear fiber itself, it is easier to achieve single transverse mode laser output. Furthermore, the large specific surface area of ​​the nonlinear fiber itself can better avoid heat accumulation and reduce the thermal effect under high power operation.

[0017] (2) Regarding laser parameters, this invention uses a laser with adjustable wavelength and adjustable repetition rate as the pump. At the same time, an optical delay line is added to the optical parametric resonator to control the cavity length, which makes it easier to match the pump light repetition rate with the cavity length. Therefore, it is also easier to meet the oscillation conditions of the optical parametric oscillator. Secondly, since the phase matching condition of the optical parametric oscillator is related to the pump wavelength, the wavelength of the ultraviolet laser can be changed by adjusting the pump wavelength. The tuning of the pump wavelength is accomplished by an electrically controlled tunable fiber filter, which has high efficiency and high convenience. Secondly, since the working bandwidth of the tunable filter is very narrow (<1nm), the green light generated will also have a narrow spectral width according to theoretical analysis. Narrow spectrum is more likely to excite four-wave mixing effect, so the generation efficiency of ultraviolet laser will also be higher. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of this utility model. Detailed Implementation

[0019] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0020] Please see Figure 1 This utility model provides a technical solution: an ultraviolet fiber optical parametric oscillator based on tunable picosecond green light, including a 1μm laser system with high power wavelength and repetition rate adjustable, a high power second harmonic generation device, and a fiber optical parametric oscillator.

[0021] The high-power, wavelength- and repetition-rate-tunable 1μm laser system includes a mode-locked fiber laser, a pulse stretcher, a tunable fiber filter, a fiber preamplifier, a fiber collimator, and a solid-state amplifier, wherein the mode-locked fiber laser, pulse stretcher, tunable fiber filter, fiber preamplifier, fiber collimator, and solid-state multi-pass or regenerative amplifier are connected in sequence.

[0022] The solid-state amplifier receives the signal light output from the fiber collimator and further amplifies the signal light power to tens of watts. The amplified signal light is then injected into a high-power second harmonic generation device composed of a nonlinear optical crystal.

[0023] The fiber optic parametric oscillator includes a nonlinear fiber, an optical delay line, and an optical cavity mirror.

[0024] In this invention, the solid-state amplifier includes a solid-state multi-pass amplifier and a solid-state regenerative amplifier.

[0025] In this invention, the optical cavity mirror includes a dichroic mirror, a total reflection mirror, and an output mirror.

[0026] In this invention, the adjustable fiber optic filter has a working bandwidth of <1nm and is used to perform spectral filtering on the broadened mode-locked pulse to achieve pulse output with a wavelength continuously adjustable from 1035-1065nm and a spectral bandwidth of <1nm.

[0027] In this invention, the high-power picosecond green light, acting as a pump, is transmitted through a dichroic mirror and coupled into a nonlinear optical fiber. The ultraviolet laser generated by the four-wave mixing effect excited by the picosecond green light is produced in the nonlinear optical fiber and forms a stable resonance in a resonant cavity composed of an optical delay line, a dichroic mirror, a nonlinear optical fiber, a total reflection mirror, and an output mirror. Part of the energy is output through the output mirror.

[0028] This invention proposes a pump laser generation technology with adjustable wavelength and repetition rate. Driven by an electrically controlled fiber optic filter, the wavelength of the ultraviolet laser can be flexibly adjusted. Secondly, narrowband filtering technology improves the generation efficiency of the ultraviolet laser. Thirdly, an optical parametric oscillator based on nonlinear fiber is designed to achieve a more compact resonant cavity structure, suppressing the impact of thermal effects on system efficiency and stability, and outputting ultraviolet laser with excellent spot pattern. Finally, the dispersion parameters of the nonlinear fiber can be adjusted to optimize the phase matching conditions of the four-wave mixing, thereby improving the efficiency and wavelength tuning range of the ultraviolet laser.

[0029] This invention relates to a mode-locked fiber laser that generates mode-locked pulses with a wavelength range of 1035-1065 nm and a repetition frequency of 40 MHz (adjustable). The generated mode-locked pulses are then input to a stretcher, which stretches the pulse width to tens of ps, thereby suppressing nonlinear effects during subsequent amplification. An adjustable fiber filter with a working bandwidth of <1 nm is used to perform spectral filtering on the stretched mode-locked pulses, achieving continuously adjustable pulse output with a wavelength range of 1035-1065 nm and a spectral bandwidth of <1 nm. An fiber preamplifier is used to increase the power of the filtered pulses. Upgrading to the watt level, the fiber collimator is used to output the pre-amplified ultrashort pulse from the fiber to free space. The solid-state amplifier receives the signal light output from the collimator and further amplifies the signal light power to tens of watts. The amplified signal light is injected into a high-power second harmonic generation device composed of nonlinear optical crystals. The laser wavelength is tunably converted from 1035-1065nm to tunable green light in the 517-532nm range, with an output power of several watts. Subsequently, the tunable picosecond green light in the 517-532nm range will be used as pump light and injected into the fiber optical parametric oscillator.

[0030] This invention uses nonlinear optical fiber as a nonlinear medium to realize optical parametric processes. An optical delay line is used to adjust the cavity length of the resonant cavity to achieve matching with the pump light repetition rate. With the injection of pump green light, by adjusting the parameters of the optical parametric resonant cavity, the wavelength-tunable ultraviolet picosecond laser output will be finally realized.

[0031] The contents not described in detail in this specification are prior art known to those skilled in the art. Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A UV fiber optic parametric oscillator based on tunable picosecond green light, characterized in that: It includes a 1μm laser system with adjustable high power wavelength and repetition rate, a high-power second harmonic generation device, and a fiber optic parametric oscillator; The high-power, wavelength- and repetition-rate-tunable 1μm laser system includes a mode-locked fiber laser, a pulse stretcher, a tunable fiber filter, a fiber preamplifier, a fiber collimator, and a solid-state amplifier, wherein the mode-locked fiber laser, pulse stretcher, tunable fiber filter, fiber preamplifier, fiber collimator, and solid-state multi-pass or regenerative amplifier are connected in sequence. The solid-state amplifier receives the signal light output from the fiber collimator and further amplifies the signal light power to tens of watts. The amplified signal light is then injected into a high-power second harmonic generation device composed of a nonlinear optical crystal. The fiber optic parametric oscillator includes a nonlinear fiber, an optical delay line, and an optical cavity mirror.

2. The ultraviolet fiber optical parametric oscillator based on tunable picosecond green light according to claim 1, characterized in that: The solid-state amplifier includes a solid-state multi-pass amplifier or a solid-state regenerative amplifier.

3. The ultraviolet fiber optical parametric oscillator based on tunable picosecond green light according to claim 1, characterized in that: The optical cavity mirror includes a dichroic mirror, a total reflection mirror, and an output mirror.

4. The ultraviolet fiber optical parametric oscillator based on tunable picosecond green light according to claim 1, characterized in that: The operating bandwidth of the tunable fiber optic filter is <1nm.

5. The ultraviolet fiber optical parametric oscillator based on tunable picosecond green light according to claim 3, characterized in that: The high-power picosecond green light is used as a pump and is transmitted through a dichroic mirror and coupled into a nonlinear fiber. The ultraviolet laser generated by the four-wave mixing effect excited by the picosecond green light is generated in the nonlinear fiber and forms a stable resonance in a resonant cavity composed of an optical delay line, a dichroic mirror, a nonlinear fiber, a total reflection mirror, and an output mirror. Part of the energy is output by the output mirror.

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