Buffer gas enhancing of power conversion efficiency of continuous-wave acetylene-filled fiber gas laser at 3 μm wavelength

In this paper, we report the use of ammonia as the buffer gas in the acetylene-filled hollow-core fiber gas laser (A-HCFGL) in which the power conversion efficiency of continuous-wave (CW) operation reaches a record of 35.74 %, the highest reported so far to the best of our knowledge. The intermolecular collision with ammonia assists the depopulation of lower laser level of acetylene which otherwise relies on the non-radiation relaxation by collision with the fiber core only. About 3.9 W CW laser output power is achieved at 3.1 μm wavelength. A numerical model illustrates the buffer gas enhancement effect and explore the optimization of A-HCFGL for high output power and slope efficiency.