The phase summation effect in sum-frequency mixing process is utilized to avoid a nonlinearity obstacle in the power scaling of single-frequency visible or ultraviolet lasers.Two single-frequency fundamental lasers ar...The phase summation effect in sum-frequency mixing process is utilized to avoid a nonlinearity obstacle in the power scaling of single-frequency visible or ultraviolet lasers.Two single-frequency fundamental lasers are spectrally broadened by phase modulation to suppress stimulated Brillouin scattering in fiber amplifier and achieve higher power.After sum-frequency mixing in a nonlinear optical crystal,the upconverted laser returns to single frequency due to phase summation,when the phase modulations on two fundamental lasers have a similar amplitude but opposite sign.The method was experimentally proved in a Raman fiber amplifier-based laser system,which generated a power-scalable sideband-free single-frequency 590 nm laser.The proposal manifests the importance of phase operation in wave-mixing processes for precision laser technology.展开更多
A continuous-wave(CW)single-longitudinal-mode(SLM)Raman laser at 1240 nm with power of up to 20.6 W was demonstrated in a free-running diamond Raman oscillator without any axial-mode selection elements.The SLM operati...A continuous-wave(CW)single-longitudinal-mode(SLM)Raman laser at 1240 nm with power of up to 20.6 W was demonstrated in a free-running diamond Raman oscillator without any axial-mode selection elements.The SLM operation was achieved due to the spatial-hole-burning free nature of Raman gain and was maintained at the highest available pump power by suppressing the parasitic stimulated Brillouin scattering(SBS).A folded-cavity design was employed for reducing the perturbing effect of resonances at the pump frequency.At a pump power of 69 W,the maximum Stokes output reached 20.6 W,corresponding to a 30%optical-to-optical conversion efficiency from 1064to 1240 nm.The result shows that parasitic SBS is the main physical process disturbing the SLM operation of Raman oscillator at higher power.In addition,for the first time,the spectral linewidth of a CW SLM diamond Raman laser was resolved using the long-delayed self-heterodyne interferometric method,which is 105 kHz at 20 W.展开更多
The publisher apologises that due to a publishing error this article was published into volume 10(2022)rather than volume 11.Unfortunately,we are unable to correct this error and so this article has now been updated t...The publisher apologises that due to a publishing error this article was published into volume 10(2022)rather than volume 11.Unfortunately,we are unable to correct this error and so this article has now been updated to confirm the publishing volume as volume 10(2022).Any accepted and publication dates associated with the article are still correct.展开更多
High-power continuous-wave single-frequency Er-doped fiber amplifiers at 1560 nm by in-band and core pumping of a 1480 nm Raman fiber laser are investigated in detail.Both co-and counter-pumping configurations are stu...High-power continuous-wave single-frequency Er-doped fiber amplifiers at 1560 nm by in-band and core pumping of a 1480 nm Raman fiber laser are investigated in detail.Both co-and counter-pumping configurations are studied experimentally.Up to 59.1 W output and 90%efficiency were obtained in the fundamental mode and linear polarization in the co-pumped case,while less power and efficiency were achieved in the counter-pumped setup for additional loss.The amplifier performs indistinguishably in terms of laser linewidth and relative intensity noise in the frequency range up to 10 MHz for both configurations.However,the spectral pedestal is raised in co-pumping,caused by cross-phase modulation between the pump and signal laser,which is observed and analyzed for the first time.Nevertheless,the spectral pedestal is 34.9 dB below the peak,which has a negligible effect for most applications.展开更多
Stimulated Raman-scattering-based lasers provide an effective way to achieve wavelength conversion.However,thermally induced beam degradation is a notorious obstacle to power scaling and it also limits the applicable ...Stimulated Raman-scattering-based lasers provide an effective way to achieve wavelength conversion.However,thermally induced beam degradation is a notorious obstacle to power scaling and it also limits the applicable range where high output beam quality is needed.Considerable research efforts have been devoted to developing Raman materials,with diamond being a promising candidate to acquire wavelength-versatile,high-power,and high-quality output beam owing to its excellent thermal properties,high Raman gain coefficient,and wide transmission range.The diamond Raman resonator is usually designed as an external-cavity pumped structure,which can easily eliminate the negative thermal effects of intracavity laser crystals.Diamond Raman converters also provide an approach to improve the beam quality owing to the Raman cleanup effect.This review outlines the research status of diamond Raman lasers,including beam quality optimization,Raman conversion,thermal effects,and prospects for future development directions.展开更多
基金The work was partly supported by the National Natural Science Foundation of China(No.62075226).
文摘The phase summation effect in sum-frequency mixing process is utilized to avoid a nonlinearity obstacle in the power scaling of single-frequency visible or ultraviolet lasers.Two single-frequency fundamental lasers are spectrally broadened by phase modulation to suppress stimulated Brillouin scattering in fiber amplifier and achieve higher power.After sum-frequency mixing in a nonlinear optical crystal,the upconverted laser returns to single frequency due to phase summation,when the phase modulations on two fundamental lasers have a similar amplitude but opposite sign.The method was experimentally proved in a Raman fiber amplifier-based laser system,which generated a power-scalable sideband-free single-frequency 590 nm laser.The proposal manifests the importance of phase operation in wave-mixing processes for precision laser technology.
基金supported by the National Natural Science Foundation of China(No.62005073)the Program of the State Key Laboratory of Crystal Materials(No.KF2101)+3 种基金the National Key Research and Development Program of China(No.2020YFC2200300)the Program of the State Key Laboratory of Quantum Optics and Quantum Optics Devices(No.KF202207)the Research Funds of Hangzhou Institute for Advanced Study(No.2022ZZ01006)the Hangzhou Agricultural and Social Development initiative Design Project(No.2022ZDSJ0846).
文摘A continuous-wave(CW)single-longitudinal-mode(SLM)Raman laser at 1240 nm with power of up to 20.6 W was demonstrated in a free-running diamond Raman oscillator without any axial-mode selection elements.The SLM operation was achieved due to the spatial-hole-burning free nature of Raman gain and was maintained at the highest available pump power by suppressing the parasitic stimulated Brillouin scattering(SBS).A folded-cavity design was employed for reducing the perturbing effect of resonances at the pump frequency.At a pump power of 69 W,the maximum Stokes output reached 20.6 W,corresponding to a 30%optical-to-optical conversion efficiency from 1064to 1240 nm.The result shows that parasitic SBS is the main physical process disturbing the SLM operation of Raman oscillator at higher power.In addition,for the first time,the spectral linewidth of a CW SLM diamond Raman laser was resolved using the long-delayed self-heterodyne interferometric method,which is 105 kHz at 20 W.
文摘The publisher apologises that due to a publishing error this article was published into volume 10(2022)rather than volume 11.Unfortunately,we are unable to correct this error and so this article has now been updated to confirm the publishing volume as volume 10(2022).Any accepted and publication dates associated with the article are still correct.
基金supported by the National Key R&D Program of China(Nos.2020YFB1805900 and 2020YFB0408300)the National Natural Science Foundation of China(No.62075226)
文摘High-power continuous-wave single-frequency Er-doped fiber amplifiers at 1560 nm by in-band and core pumping of a 1480 nm Raman fiber laser are investigated in detail.Both co-and counter-pumping configurations are studied experimentally.Up to 59.1 W output and 90%efficiency were obtained in the fundamental mode and linear polarization in the co-pumped case,while less power and efficiency were achieved in the counter-pumped setup for additional loss.The amplifier performs indistinguishably in terms of laser linewidth and relative intensity noise in the frequency range up to 10 MHz for both configurations.However,the spectral pedestal is raised in co-pumping,caused by cross-phase modulation between the pump and signal laser,which is observed and analyzed for the first time.Nevertheless,the spectral pedestal is 34.9 dB below the peak,which has a negligible effect for most applications.
基金supported by the National Natural Science Foundation of China(Nos.62005075,61927815,and 61905061)Hebei Science and Technology Research Project(No.QN2020182)Hebei Natural Science Foundation(Nos.F2020202029 and F2020202026)。
文摘Stimulated Raman-scattering-based lasers provide an effective way to achieve wavelength conversion.However,thermally induced beam degradation is a notorious obstacle to power scaling and it also limits the applicable range where high output beam quality is needed.Considerable research efforts have been devoted to developing Raman materials,with diamond being a promising candidate to acquire wavelength-versatile,high-power,and high-quality output beam owing to its excellent thermal properties,high Raman gain coefficient,and wide transmission range.The diamond Raman resonator is usually designed as an external-cavity pumped structure,which can easily eliminate the negative thermal effects of intracavity laser crystals.Diamond Raman converters also provide an approach to improve the beam quality owing to the Raman cleanup effect.This review outlines the research status of diamond Raman lasers,including beam quality optimization,Raman conversion,thermal effects,and prospects for future development directions.