Study of two Specific Frequency-selecting Procedures for All-fiber Single-frequency Lasers

Abstract

In this paper, a detailed study of two specific frequency-selecting procedures for all-fiber single-frequency lasers is presented. The frequency-selection has been realized by using a multi-ring cavity (MRC) and double Mach-Zehnder interferometer (MZI), respectively. Firstly, the frequency-selecting principles of two procedures have been simply summarized, and the influences of the sub-ring lengths in the MRC, the optical path difference between two arms of a MZI, and the length of the primary ring cavity on single-frequency lasers have been analysed in detail. Then, the 1064.3 nm single-frequency emission with the linewidth <10 kHz in the same Ytterbium-doped fiber laser scheme has been achieved by employing two different procedures. Finally, the pump power thresholds of the MRC-based and MZI-based single-frequency fiber lasers were measured as 60 and 70 mW, the slope efficiencies were measured as 6.5 and 5.3%, and the side-mode suppression ratios were measured as 45 and 48 dB, respectively. The results reveal that the MRC-based single frequency fiber lasers have the higher energy efficiency while the MZI-based ones have the better mode stability.