Study on 1.55 μm Raman laser in ethane gas pumped by 1064 nm pulsed laser

Stimulated Raman scattering is an effective non-linear frequency conversion method, and has received much attention. However, Raman lasers also have drawbacks, such as wavelength of Raman lasers could not be tuned continuously, and the coverage of Raman laser wavelength is limited. Therefore, more Raman active media are required to improve the coverage of Raman lasers. In this work, 1064 nm laser was used as pump source, and pressurized ethane was used as Raman active medium, and 1550 nm Raman laser was produced. Neither obvious backward Raman laser nor higher orders of Stokes Raman lasers were observed in this experiment. By the optimization of experimental parameters, laser induced breakdown was reduced; the first order Stokes(S1) Raman laser photon conversion efficiency was improved to 20.7%, and the maximum S₁ energy was 21.2 mJ. Ethane was found to have significant absorption at wavelength of 1550 nm, this was the major reason for the limited photon conversion efficiency and pulse energy of S₁ laser. The absorption coefficient of ethane at 1550 nm was measured to be 5.71$ \times {{10}}^{-{8}} $ m⁻¹ ·Pa⁻¹, and the absorption cross section was measured to be $ {2.3}{5} \times {{10}}^{-{24}}{\text{ cm}}^{{2}} $.