Influence of a feedback coupling on operating characteristics of a Cr3+: LiSrAlF6 laser using an end-coupled fiber grating

We describe a comparative study related to an influence of a feedback coupl ing on operating characteristics of a cw Cr3+:LiSrAlF6 (Cr3+:LiSAF) laser u sing an end-coupled fiber grating with different coupling configurations. T o achieve a compact construction, a direct butt-coupling of the fiber grati ng at the pump end of the Cr3+:LISAF laser and pumping through the same fib er was considered. The feedback provided by the coupled fiber grating throu gh an end mirror was responsible for a spectrally narrowed output with a sl ope efficiency of 11%. However, the performance critically depended on an a mount of the feedback coupling. The feedback-coupling condition was improve d considerably by using a lens-coupled fiber grating at the pump end of the Cr3+:LiSAF crystal. A spectrally narrowed output of approximate to 0.15 cm (-1) was obtained, and the output slope efficiency was measured as 27%. The oretical modeling was also per formed to understand the effect of the feedb ack coupling and the results agreed well with the experimental observations .