In this paper, we propose and experimentally investigate a linearly polarized narrow-linewidth random fiber laser(RFL) operating at 1080 nm and boost the output power to kilowatt level with near-diffraction-limited be...In this paper, we propose and experimentally investigate a linearly polarized narrow-linewidth random fiber laser(RFL) operating at 1080 nm and boost the output power to kilowatt level with near-diffraction-limited beam quality using a master oscillation power amplifier. The RFL based on a half-opened cavity, which is composed of a linearly polarized narrow-linewidth fiber Bragg grating and a 500 m piece of polarization-maintained Ge-doped fiber, generates a 0.71 W seed laser with an 88 pm full width at half-maximum(FWHM) linewidth and a 22.5 dB polarization extinction ratio(PER) for power scaling. A two-stage fiber amplifier enhances the seed laser to the maximal 1.01 k W with a PER value of 17 dB and a beam quality of M_x^2=1.15 and M_y^2=1.13. No stimulated Brillouin scattering effect is observed at the ultimate power level, and the FWHM linewidth of the amplified random laser broadens linearly as a function of the output power with a coefficient of about 0.1237 pm∕W.To the best of our knowledge, this is the first demonstration of a linearly polarized narrow-linewidth RFL with even kilowatt-level near-diffraction-limited output, and further performance scaling is ongoing.展开更多
We propose a theoretical model to describe external-cavity distributed feedback semiconductor lasers and investigate the impact of the number of external feedback points on linewidth and side-mode suppression ratio th...We propose a theoretical model to describe external-cavity distributed feedback semiconductor lasers and investigate the impact of the number of external feedback points on linewidth and side-mode suppression ratio through numerical simulation. The simulation results demonstrate that the linewidth of external-cavity semiconductor lasers can be reduced by increasing the external cavity length and feedback ratio, and adding more external feedback points can further narrow the linewidth and enhance the side mode suppression ratio. This research provides insight into the external cavity distributed feedback mechanism and can guide the design of high-performance external cavity semiconductor lasers. .展开更多
High frequency stability, narrow-linewidth lasers have been long dreamed of since the invention of the laser. They have recently developed dramatically due to the advent of optical clocks. State-of-the-art narrow-line...High frequency stability, narrow-linewidth lasers have been long dreamed of since the invention of the laser. They have recently developed dramatically due to the advent of optical clocks. State-of-the-art narrow-linewidth lasers have been constructed by using the Pound-Drever-Hall (PDH) technique to lock the laser frequencies to the resonance of ultra-stable external optical cavities with high finesse. This paper introduces the developments of narrow-linewidth lasers, with a focus on the improvements of length stability of optical reference cavities, including optical cavity designs of vibration insensitivity and low thermal noise. Future trends and alternative methods for narrow-linewidth lasers are also discussed.展开更多
We report two ultra-stable laser systems automatically frequency-stabilized to two high-finesse optical cavities.By employing analog-digital hybrid proportional integral derivative(PID)controllers,we keep the merits o...We report two ultra-stable laser systems automatically frequency-stabilized to two high-finesse optical cavities.By employing analog-digital hybrid proportional integral derivative(PID)controllers,we keep the merits of wide servo bandwidth and servo accuracy by using analog circuits for the PID controller,and,at the same time,we realize automatic laser frequency locking by introducing digital logic into the PID controller.The lasers can be automatically frequency-stabilized to their reference cavities,and it can be relocked in 0.3 s when interruption happens,i.e.,blocking and unblocking the laser light.These automatic frequency-stabilized lasers are measured to have a frequency instability of 6×10^(-16)at 1 s averaging time and a most probable linewidth of 0.3 Hz.The laser systems were tested for continuous operation over 11 days.Such ultrastable laser systems in long-term robust operation will be beneficial to the applications of optical atomic clocks and precision measurement based on frequency-stabilized lasers.展开更多
We report a novel single-frequency fibre ring laser using self-injection locking with a distributed-feedback （DFB） fibre laser at 1550nm. The operating wavelength is controlled by a saturable absorber and a DFB fibr...We report a novel single-frequency fibre ring laser using self-injection locking with a distributed-feedback （DFB） fibre laser at 1550nm. The operating wavelength is controlled by a saturable absorber and a DFB fibre laser in the ring cavity, the saturable absorber acts as a narrow band-pass filter. In the primary experiment, the laser output exceeds 100mW with the linewidth less than 2kHz. The laser is stable, and no mode-hopping is observed within eight hours. Compared with other cavity designs using spatial hole-burning, our laser shows high controllability.展开更多
A theoretical introduction of saturable absorber based on standing-wave saturation effects as a transient fiber Bragg grating （FBG） was presented. The central wavelength of the transient FBG was located in 2 μm. Th...A theoretical introduction of saturable absorber based on standing-wave saturation effects as a transient fiber Bragg grating （FBG） was presented. The central wavelength of the transient FBG was located in 2 μm. The factors affecting the bandwidth and the reflectivity of the transient FBG were analyzed. The linewidth and reflectiv- ity as the function of doped fiber length and doping concentration were correspondingly simulated by Matlab software. It was found that the larger the doping concentration and the fiber length were, the smaller the bandwidth was. These results suggest that the performance of the transient FBG can be optimized by choosing the appropriate length of doped fiber and the larger doping concentration, which can be used as a reference for the narrow-linewidth fiber laser around 2 μm.展开更多
We report on a compact, stable, all-fiberized narrow-linewidth(0.045 nm) pulsed laser source emitting laser beam with a wavelength of 266 nm, and tunable pulse width and repetition rate. The system is based on all-fib...We report on a compact, stable, all-fiberized narrow-linewidth(0.045 nm) pulsed laser source emitting laser beam with a wavelength of 266 nm, and tunable pulse width and repetition rate. The system is based on all-fiberized nanosecond amplifier architecture, which consists of Yb-doped fiber preamplifiers and a super-large-mode-area Yb-doped fiber power amplifier. The fiber amplifier with a core of 50 μm is used to raise the threshold of the stimulated Brillouin scattering(SBS) effect and to obtain high output power and single pulse energy. Using lithium triborate(LBO) crystal and betabarium borate(BBO) crystal for realizing the second-harmonic generation(SHG) and fourth-harmonic generation(FHG),we achieve 17 μJ(1.73 W) and 0.66 μJ(66 mW), respectively, at wavelengths of 532 nm and 266 nm and a repetition rate of 100 kHz with pulse width of 4 ns. This source has great potential applications in fluorescence research and solar-blind ultraviolet optical communication.展开更多
The generation of supercontinuum(SC) often requires ultrashort pulsed lasers with high peak power and gain media with large nonlinear coefficients,such as a long piece of fiber or photonic crystal fiber.In this Letter...The generation of supercontinuum(SC) often requires ultrashort pulsed lasers with high peak power and gain media with large nonlinear coefficients,such as a long piece of fiber or photonic crystal fiber.In this Letter,we propose and demonstrate that high-power SC can be generated through a simple narrow-bandwidth fiber Bragg gratings(FBGs)-based laser cavity without any modulation,based on the mechanism of intense nonlinear effects induced by the inherent self-pulsation generated inside the cavity.In the experiment,an ~80 W SC laser with the spectrum range from <600 nm to 1600 nm was achieved.To the best of our knowledge,this is the first report about SC generation through a simple fiber laser cavity.This work enriches the research content of SC and provides a cost-effective method for high-power SC lasers.展开更多
A distributed feedback （DFB） fiber laser with a ratio of the backward to forward output power of 1：100 was composed by a 45-ram-length asymmetrical phase-shifted fiber grating fabricated on the 50-mm erbium-doped p...A distributed feedback （DFB） fiber laser with a ratio of the backward to forward output power of 1：100 was composed by a 45-ram-length asymmetrical phase-shifted fiber grating fabricated on the 50-mm erbium-doped photosensitive fiber. Forward output laser was amplified using a certain length of Nufern EDFL-980-Hp erbium-doped fiber to absorb the surplus pump power after the active phase-shifted fiber grating and get population inversion. By using OptiSystem software, the best fiber length of the EDFL to get the highest gain was simulated. In order to keep the amplified laser with the narrow line-width and low noise, a narrow-band light filter consisting of a fiber Bragg grating （FBG） with the same Bragg wavelength as the laser and an optical circulator was used to filter the amplified spontaneous emission （ASE） noise of the out-cavity erbium-doped fiber. The designed laser structure sufficiently utilized the pump power, and a DFB fiber laser with the 32.5-mW output power, l l.5-kHz line width, and -87-dB/Hz relative intensity noise （R1N） at 300 mW of 980 nm pump power was brought out.展开更多
基金National Natural Science Foundation of China(NSFC)(61322505,61635005)
文摘In this paper, we propose and experimentally investigate a linearly polarized narrow-linewidth random fiber laser(RFL) operating at 1080 nm and boost the output power to kilowatt level with near-diffraction-limited beam quality using a master oscillation power amplifier. The RFL based on a half-opened cavity, which is composed of a linearly polarized narrow-linewidth fiber Bragg grating and a 500 m piece of polarization-maintained Ge-doped fiber, generates a 0.71 W seed laser with an 88 pm full width at half-maximum(FWHM) linewidth and a 22.5 dB polarization extinction ratio(PER) for power scaling. A two-stage fiber amplifier enhances the seed laser to the maximal 1.01 k W with a PER value of 17 dB and a beam quality of M_x^2=1.15 and M_y^2=1.13. No stimulated Brillouin scattering effect is observed at the ultimate power level, and the FWHM linewidth of the amplified random laser broadens linearly as a function of the output power with a coefficient of about 0.1237 pm∕W.To the best of our knowledge, this is the first demonstration of a linearly polarized narrow-linewidth RFL with even kilowatt-level near-diffraction-limited output, and further performance scaling is ongoing.
文摘We propose a theoretical model to describe external-cavity distributed feedback semiconductor lasers and investigate the impact of the number of external feedback points on linewidth and side-mode suppression ratio through numerical simulation. The simulation results demonstrate that the linewidth of external-cavity semiconductor lasers can be reduced by increasing the external cavity length and feedback ratio, and adding more external feedback points can further narrow the linewidth and enhance the side mode suppression ratio. This research provides insight into the external cavity distributed feedback mechanism and can guide the design of high-performance external cavity semiconductor lasers. .
基金supported by the National Basic Research Program of China("973"Project)(Grant Nos.2010CB922903,2012CB821302)the National Natural Science Foundation of China(Grant Nos.11104077,11127405)
文摘High frequency stability, narrow-linewidth lasers have been long dreamed of since the invention of the laser. They have recently developed dramatically due to the advent of optical clocks. State-of-the-art narrow-linewidth lasers have been constructed by using the Pound-Drever-Hall (PDH) technique to lock the laser frequencies to the resonance of ultra-stable external optical cavities with high finesse. This paper introduces the developments of narrow-linewidth lasers, with a focus on the improvements of length stability of optical reference cavities, including optical cavity designs of vibration insensitivity and low thermal noise. Future trends and alternative methods for narrow-linewidth lasers are also discussed.
基金supported by the National Natural Science Foundation of China(No.11927810)。
文摘We report two ultra-stable laser systems automatically frequency-stabilized to two high-finesse optical cavities.By employing analog-digital hybrid proportional integral derivative(PID)controllers,we keep the merits of wide servo bandwidth and servo accuracy by using analog circuits for the PID controller,and,at the same time,we realize automatic laser frequency locking by introducing digital logic into the PID controller.The lasers can be automatically frequency-stabilized to their reference cavities,and it can be relocked in 0.3 s when interruption happens,i.e.,blocking and unblocking the laser light.These automatic frequency-stabilized lasers are measured to have a frequency instability of 6×10^(-16)at 1 s averaging time and a most probable linewidth of 0.3 Hz.The laser systems were tested for continuous operation over 11 days.Such ultrastable laser systems in long-term robust operation will be beneficial to the applications of optical atomic clocks and precision measurement based on frequency-stabilized lasers.
文摘We report a novel single-frequency fibre ring laser using self-injection locking with a distributed-feedback （DFB） fibre laser at 1550nm. The operating wavelength is controlled by a saturable absorber and a DFB fibre laser in the ring cavity, the saturable absorber acts as a narrow band-pass filter. In the primary experiment, the laser output exceeds 100mW with the linewidth less than 2kHz. The laser is stable, and no mode-hopping is observed within eight hours. Compared with other cavity designs using spatial hole-burning, our laser shows high controllability.
基金This work was supported by the National Natural Science Foundation of China （Grant Nos. 61275083, 61290315）.
文摘A theoretical introduction of saturable absorber based on standing-wave saturation effects as a transient fiber Bragg grating （FBG） was presented. The central wavelength of the transient FBG was located in 2 μm. The factors affecting the bandwidth and the reflectivity of the transient FBG were analyzed. The linewidth and reflectiv- ity as the function of doped fiber length and doping concentration were correspondingly simulated by Matlab software. It was found that the larger the doping concentration and the fiber length were, the smaller the bandwidth was. These results suggest that the performance of the transient FBG can be optimized by choosing the appropriate length of doped fiber and the larger doping concentration, which can be used as a reference for the narrow-linewidth fiber laser around 2 μm.
基金Project supported by the Key Program of Beijing Municipal Natural Science Foundation, China (Grant No. KZ201910005006)the National Nature Science Foundation of China (Grant No. 62005004)+1 种基金the Natural Science Foundation of Beijing Municipality, China (Grant No. 4204091)the National Science Foundation for Postdoctor Scientists of China (Grant No. 212423)。
文摘We report on a compact, stable, all-fiberized narrow-linewidth(0.045 nm) pulsed laser source emitting laser beam with a wavelength of 266 nm, and tunable pulse width and repetition rate. The system is based on all-fiberized nanosecond amplifier architecture, which consists of Yb-doped fiber preamplifiers and a super-large-mode-area Yb-doped fiber power amplifier. The fiber amplifier with a core of 50 μm is used to raise the threshold of the stimulated Brillouin scattering(SBS) effect and to obtain high output power and single pulse energy. Using lithium triborate(LBO) crystal and betabarium borate(BBO) crystal for realizing the second-harmonic generation(SHG) and fourth-harmonic generation(FHG),we achieve 17 μJ(1.73 W) and 0.66 μJ(66 mW), respectively, at wavelengths of 532 nm and 266 nm and a repetition rate of 100 kHz with pulse width of 4 ns. This source has great potential applications in fluorescence research and solar-blind ultraviolet optical communication.
基金supported by the National Natural Science Foundation of China (Nos. 62035015 and 62005316)the Innovative Research Groups of Hunan Province (No. 2019JJ10005)
文摘The generation of supercontinuum(SC) often requires ultrashort pulsed lasers with high peak power and gain media with large nonlinear coefficients,such as a long piece of fiber or photonic crystal fiber.In this Letter,we propose and demonstrate that high-power SC can be generated through a simple narrow-bandwidth fiber Bragg gratings(FBGs)-based laser cavity without any modulation,based on the mechanism of intense nonlinear effects induced by the inherent self-pulsation generated inside the cavity.In the experiment,an ~80 W SC laser with the spectrum range from <600 nm to 1600 nm was achieved.To the best of our knowledge,this is the first report about SC generation through a simple fiber laser cavity.This work enriches the research content of SC and provides a cost-effective method for high-power SC lasers.
文摘A distributed feedback （DFB） fiber laser with a ratio of the backward to forward output power of 1：100 was composed by a 45-ram-length asymmetrical phase-shifted fiber grating fabricated on the 50-mm erbium-doped photosensitive fiber. Forward output laser was amplified using a certain length of Nufern EDFL-980-Hp erbium-doped fiber to absorb the surplus pump power after the active phase-shifted fiber grating and get population inversion. By using OptiSystem software, the best fiber length of the EDFL to get the highest gain was simulated. In order to keep the amplified laser with the narrow line-width and low noise, a narrow-band light filter consisting of a fiber Bragg grating （FBG） with the same Bragg wavelength as the laser and an optical circulator was used to filter the amplified spontaneous emission （ASE） noise of the out-cavity erbium-doped fiber. The designed laser structure sufficiently utilized the pump power, and a DFB fiber laser with the 32.5-mW output power, l l.5-kHz line width, and -87-dB/Hz relative intensity noise （R1N） at 300 mW of 980 nm pump power was brought out.
