Realization of an O-waveband laser based on cascaded stimulated Raman scattering of microspheres.

We report an experimental realization of five-order Stokes stimulated Raman scattering lasing in silica microspheres pumped by a 1030 nm continuous-wave laser. The wavelength of the Stokes Raman laser is extended to 1348.55 nm, which is located in the second low loss window of the optical fiber. It has potential applications in the wavelength converter and Raman amplifier in O-waveband optical communication. The minimum pump power is about 50 µW when the first-order Stokes Raman laser can be observed.

2 µm laser oscillation of Ho3+:Tm3+-codoped silica microspheres.

2 µm laser oscillation with a low threshold has been achieved in Ho3+:Tm3+-codoped silica microspheres (HTCSMs). Ho3+:Tm3+-codoped solgel functionalization film is applied to the surface of a silica microsphere, and an optical tapered fiber is adopted to couple an 808 nm continuous-wave laser to serve as the pump light source. Multimode and single-mode laser oscillations around 2 µm within the eye-safe wave band are observed due to the I75→I85 transitions of Ho3+ ions sensitized by Tm3+. The morphology characteristics of microspheres determine the multimode laser oscillation spectrum. The free spectral range is in good accordance with the calculated value based on Mie scattering theory. The HTCSM laser oscillation shows characteristics of good capability, simple process, high flexibility, and low cost.