Nonlinear optical gain modulation(NOGM)is an effective approach for generating highly coherent femtosecond Raman pulses.In a typical NOGM system,the pump pulse energy boosting unit and nonlinear frequency conversion u...Nonlinear optical gain modulation(NOGM)is an effective approach for generating highly coherent femtosecond Raman pulses.In a typical NOGM system,the pump pulse energy boosting unit and nonlinear frequency conversion unit are separated,which poses a difficulty in generating Raman solitons with pulse energy over theμJ level.Here,we demonstrate an integrated ultrafast ytterbium-Raman fiber amplifier,which accomplishes pump pulse amplification and Raman pulse conversion simultaneously in ytterbium-doped fiber(YDF).The integrated ytterbium-Raman fiber amplifier could generate approximately 1μJ 1121 nm Raman pulses with a pulse duration of 589 fs under a conversion efficiency of 69.9%.The result represents the highest pulse energy experimentally recorded in NOGM systems.Simulation further reveals that YDF gain could promote Raman conversion efficiency and reduce nonlinear chirp accumulation,which leads to improved performance of generated Raman pulses.Meanwhile,the feasibility of generating 10μJ level Raman pulses using such a hybrid gain setup was also confirmed numerically.展开更多
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
基金supported by the National Key R&D Program of China(Grant No.2024YFB3907802)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2022247)+1 种基金the National Natural Science Foundation of China(Grant Nos.62175244,62075226,12341404 and 62305358)the Natural Science Foundation of Shanghai(Grant No.21ZR1472200).
文摘Nonlinear optical gain modulation(NOGM)is an effective approach for generating highly coherent femtosecond Raman pulses.In a typical NOGM system,the pump pulse energy boosting unit and nonlinear frequency conversion unit are separated,which poses a difficulty in generating Raman solitons with pulse energy over theμJ level.Here,we demonstrate an integrated ultrafast ytterbium-Raman fiber amplifier,which accomplishes pump pulse amplification and Raman pulse conversion simultaneously in ytterbium-doped fiber(YDF).The integrated ytterbium-Raman fiber amplifier could generate approximately 1μJ 1121 nm Raman pulses with a pulse duration of 589 fs under a conversion efficiency of 69.9%.The result represents the highest pulse energy experimentally recorded in NOGM systems.Simulation further reveals that YDF gain could promote Raman conversion efficiency and reduce nonlinear chirp accumulation,which leads to improved performance of generated Raman pulses.Meanwhile,the feasibility of generating 10μJ level Raman pulses using such a hybrid gain setup was also confirmed numerically.
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.
