External optical feedback effects due to reflection, Rayleigh backscattering and coherent Rayleigh backseattering in fiber distributed feedback (DFB) fiber laser sensor system have been investigated. If the feedback...External optical feedback effects due to reflection, Rayleigh backscattering and coherent Rayleigh backseattering in fiber distributed feedback (DFB) fiber laser sensor system have been investigated. If the feedback intensity exceeds critical amount, excess noise would be induced in the demodulator. The maximum tolerable intensity back-reflection coefficient Rc and backscattering coefficient Sc into a fiber DFB laser with lead fiber length from I m to 37.5 km before the onset of instabilities are shown. Rc is found to decrease with increasing lead fiber length while Sc was relatively invariable with varying fiber length. The coherent Rayleigh backscattering (CRBS) would induce neglectable noise with a lead fiber exceeding 13.5 kin. To eliminate these noises, one or two isolators should be incorporated in the system.展开更多
In this paper,a spectral beam combining(SBC)structure of multi-single emitters laser diode based on a polarization full feedback(PFF)external cavity is proposed and demonstrated.The maximum combining efficiency is 75....In this paper,a spectral beam combining(SBC)structure of multi-single emitters laser diode based on a polarization full feedback(PFF)external cavity is proposed and demonstrated.The maximum combining efficiency is 75.6%,which leads to an output power of 38.48 W,a degree of polarization(DOP)of 99.42%,and electro-optical conversion efficiency of 35.63%under continuous wave operation at a current of 8 A.Compared to the conventional SBC,the output power,the combining efficiency,the electro-optical conversion efficiency,and the DOP of the PFF-SBC structure present improvements of 5.73 W,11.26 percentage points,5.3 percentage points,and 7.26 percentage points,respectively.The results show that this SBC method can achieve a high efficiency and linearly polarized laser output of SBC,thereby making the subsequent polarization beam-combining efficiency approach the limit.展开更多
In this research,the highly efficient external cavity feedback technology based on volume Bragg grating(VBG)is studied.By using the structure of a fast axis collimating lens,the beam transformation system,a slow axis ...In this research,the highly efficient external cavity feedback technology based on volume Bragg grating(VBG)is studied.By using the structure of a fast axis collimating lens,the beam transformation system,a slow axis collimating lens,and VBG,the divergence angle of the fast and slow axes of the diode laser incident on the VBG is reduced effectively,and the feedback efficiency of the external cavity is improved.Combined with beam combining technology,fiber coupling technology,and precision temperature control technology,a high-power and narrow-linewidth diode laser pump source of kilowatt class is realized for alkali metal vapor laser pumping.The core diameter of the optical fiber is 1000μm,the numerical aperture is 0.22,the output power from the fiber is 1013 W,the fiber coupling efficiency exceeds 89%,and the external cavity efficiency exceeds 91%.The central wavelength is 852.052 nm(in air),which is tunable from 851.956 nm to 852.152 nm,and the spectral linewidth is 0.167 nm.Research results can be used for cesium alkali metal vapor laser pumping.展开更多
基金supported by the National 863 Program under Grant No. 2007AA03Z415.
文摘External optical feedback effects due to reflection, Rayleigh backscattering and coherent Rayleigh backseattering in fiber distributed feedback (DFB) fiber laser sensor system have been investigated. If the feedback intensity exceeds critical amount, excess noise would be induced in the demodulator. The maximum tolerable intensity back-reflection coefficient Rc and backscattering coefficient Sc into a fiber DFB laser with lead fiber length from I m to 37.5 km before the onset of instabilities are shown. Rc is found to decrease with increasing lead fiber length while Sc was relatively invariable with varying fiber length. The coherent Rayleigh backscattering (CRBS) would induce neglectable noise with a lead fiber exceeding 13.5 kin. To eliminate these noises, one or two isolators should be incorporated in the system.
基金This work was supported by the Key Technology Research and Development Program of Shandong(Nos.2022CXGC020104 and 2023ZLYS03)the Key-Area Research and Development Program of Guangdong Province(No.2020B090922003).
文摘In this paper,a spectral beam combining(SBC)structure of multi-single emitters laser diode based on a polarization full feedback(PFF)external cavity is proposed and demonstrated.The maximum combining efficiency is 75.6%,which leads to an output power of 38.48 W,a degree of polarization(DOP)of 99.42%,and electro-optical conversion efficiency of 35.63%under continuous wave operation at a current of 8 A.Compared to the conventional SBC,the output power,the combining efficiency,the electro-optical conversion efficiency,and the DOP of the PFF-SBC structure present improvements of 5.73 W,11.26 percentage points,5.3 percentage points,and 7.26 percentage points,respectively.The results show that this SBC method can achieve a high efficiency and linearly polarized laser output of SBC,thereby making the subsequent polarization beam-combining efficiency approach the limit.
基金This work was supported by the National Natural Science Foundation of China(NSFC)(No.61991433)Pilot Project of CAS(No.XDB43030302)+2 种基金Equipment Pre-research(No.2006ZYGG0304)Key Research and Development Project of Guangdong Province(No.2020B090922003)R&D Program of Jilin Province(No.20190302042GX).
文摘In this research,the highly efficient external cavity feedback technology based on volume Bragg grating(VBG)is studied.By using the structure of a fast axis collimating lens,the beam transformation system,a slow axis collimating lens,and VBG,the divergence angle of the fast and slow axes of the diode laser incident on the VBG is reduced effectively,and the feedback efficiency of the external cavity is improved.Combined with beam combining technology,fiber coupling technology,and precision temperature control technology,a high-power and narrow-linewidth diode laser pump source of kilowatt class is realized for alkali metal vapor laser pumping.The core diameter of the optical fiber is 1000μm,the numerical aperture is 0.22,the output power from the fiber is 1013 W,the fiber coupling efficiency exceeds 89%,and the external cavity efficiency exceeds 91%.The central wavelength is 852.052 nm(in air),which is tunable from 851.956 nm to 852.152 nm,and the spectral linewidth is 0.167 nm.Research results can be used for cesium alkali metal vapor laser pumping.