A high-birefringence fiber,Tb:YAG crystal-derived silica fiber(TYDSF),was fabricated by CO_(2)laser-heating drawing technique.Its linear birefringence was 2.99×10^(-5),and it was used to fabricate an all-fiber qu...A high-birefringence fiber,Tb:YAG crystal-derived silica fiber(TYDSF),was fabricated by CO_(2)laser-heating drawing technique.Its linear birefringence was 2.99×10^(-5),and it was used to fabricate an all-fiber quarter-wave plate(QWP)device.The polarization extinction ratio(PER)of the device was 0.29 dB,and its ellipticity was 44.26°at 25℃.In the temperature range of-5℃to 200℃,its PER was always less than 0.80 dB,and the fluctuation of PER and ellipticity was also small.Compared with QWPs fabricated with PANDA-type polarization-maintaining fiber(PMF)and elliptical-core PMF,the performance of TYDSF QWP was least sensitive to temperature.Furthermore,the TYDSF QWP was used in a high-power laser system,still maintaining good circular polarization state,and the nonlinear effects were suppressed in the system.The experimental results are of great significance to high-power lasers,fiber-optic current sensors,etc.,in harsh environments.展开更多
The experimental investigation of mode distortion induced by stimulated Raman scattering(SRS)in a high-power fiber amplifier,which includes the evolutions of optical spectra,spatial beam profiles,and time-frequency ch...The experimental investigation of mode distortion induced by stimulated Raman scattering(SRS)in a high-power fiber amplifier,which includes the evolutions of optical spectra,spatial beam profiles,and time-frequency characteristics,has been carried out in detail.Temporal-frequency characteristics have been studied for the first time,to the best of our knowledge,by using a low-speed camera and high-speed photodiode traces,which revealed that temporal-frequency characteristics of SRS-induced mode distortion are different from traditional dynamic mode instability(MI).The experimental results show that the output beam profile remains stable before the mode distortion occurs and fluctuates obviously after the onset of SRS-induced MI but on a time scale of seconds,which is much lower than that of Yb-gain-induced MI featuring millisecond-level beam profile fluctuation.It also shows that the mode distortion became measurable in company with the onset of inter-mode four-wave mixing(IM-FWM)when the ratio of Raman light reaches 3%;further,the beam quality factor M2degrades gradually from 1.4 to 2.1 as the ratio of Raman light increases.The mode distortion is accompanied by an obvious temperature increase of the output passive fiber,which further confirms that the mode distortion originates from SRS.The cause of the mode distortion induced by SRS has been explained in the context of core-pumped SRS effect,and the investigation on the accompanying IM-FWM effect indicates that the main content of the SRSinduced high-order mode is the LP21 mode.展开更多
基金supported by the National Natural Science Foundation of China(Nos.61935002,61975113,and 62275148)111 Project(No.D20031)+1 种基金the Shanghai Professional Technical Public Service Platform of Advanced Optical Waveguide Intelligent Manufacturing and Testing(No.19DZ2294000)the Jiangsu Province’s Industry Outlook and Key Core Technologies–Key Projects(No.BE2022055-4)。
文摘A high-birefringence fiber,Tb:YAG crystal-derived silica fiber(TYDSF),was fabricated by CO_(2)laser-heating drawing technique.Its linear birefringence was 2.99×10^(-5),and it was used to fabricate an all-fiber quarter-wave plate(QWP)device.The polarization extinction ratio(PER)of the device was 0.29 dB,and its ellipticity was 44.26°at 25℃.In the temperature range of-5℃to 200℃,its PER was always less than 0.80 dB,and the fluctuation of PER and ellipticity was also small.Compared with QWPs fabricated with PANDA-type polarization-maintaining fiber(PMF)and elliptical-core PMF,the performance of TYDSF QWP was least sensitive to temperature.Furthermore,the TYDSF QWP was used in a high-power laser system,still maintaining good circular polarization state,and the nonlinear effects were suppressed in the system.The experimental results are of great significance to high-power lasers,fiber-optic current sensors,etc.,in harsh environments.
基金National Natural Science Foundation of China(61905226)National Key Research and Development Program of China(2017YFB1104401)。
文摘The experimental investigation of mode distortion induced by stimulated Raman scattering(SRS)in a high-power fiber amplifier,which includes the evolutions of optical spectra,spatial beam profiles,and time-frequency characteristics,has been carried out in detail.Temporal-frequency characteristics have been studied for the first time,to the best of our knowledge,by using a low-speed camera and high-speed photodiode traces,which revealed that temporal-frequency characteristics of SRS-induced mode distortion are different from traditional dynamic mode instability(MI).The experimental results show that the output beam profile remains stable before the mode distortion occurs and fluctuates obviously after the onset of SRS-induced MI but on a time scale of seconds,which is much lower than that of Yb-gain-induced MI featuring millisecond-level beam profile fluctuation.It also shows that the mode distortion became measurable in company with the onset of inter-mode four-wave mixing(IM-FWM)when the ratio of Raman light reaches 3%;further,the beam quality factor M2degrades gradually from 1.4 to 2.1 as the ratio of Raman light increases.The mode distortion is accompanied by an obvious temperature increase of the output passive fiber,which further confirms that the mode distortion originates from SRS.The cause of the mode distortion induced by SRS has been explained in the context of core-pumped SRS effect,and the investigation on the accompanying IM-FWM effect indicates that the main content of the SRSinduced high-order mode is the LP21 mode.
