Research On Single-frequence Narrow Linewidth Fiber Laser Based On High Erbium-doped Fiber

Single frequency narrow linewidth fiber laser has been widely used in various fields of society and research,such as optical communication system,optical fiber sensor,coherent laser radar,microwave photonic systems and the THz generation etc,with the laser characteristics of ultra low noise,ultra low intensity interference and ultra high monochromaticity,ultra high coherence.So the study of single frequency narrow linewidth fiber laser has become the most important direction in today’s society.This paper mainly studies a high erbium-doped fiber laser of single frequence narrow linewidth,and firstly theoretical analysis the gain of erbium-doped fiber to obtain the relationship between gain medium length,erbium-doped concentration and pump power by Matlab simulation software,and hopeing to reduce the gain medium length to shorten the laser cavity length.With the help of a pair of fiber Bragg grating with high and low reflectivity at the center wavelength of 1550 nm that can control the linewidth and mode of laser,and combining the wavelength division multiplexer(WDM)to form an ultra short laser cavity.Meanwhile,one method is put forward to dealing with optical fiber facing by grinding and polishing,because of poor mechanical properties and brittle texture of highly erbium-doped fiber that can not be cut by the traditional cutting device.Then the treated fiber is connected to the optical design by docking technology for performance test.Finally one erbium-doped fiber laser and optical amplifier are proposed and demonstrated.And with high erbium-doped fiber as gain medium,the maximum gain is 19.17 dB with the pump power of 400 mW of optical amplifier;and the fiber laser output at 1549.784 nm with 20 dB linewidth of 48 kHz is observed.The fiber laser shows that the side-mode suppression ratio is 76.12 dB,the slope efficiency is 28.6%,the maximum output power is 68.39 mW of 300 mW pump power.