Single-mode silica microsphere Raman laser tunable in the U-band and beyond

We demonstrate experimentally a silica microresonator-based single-mode Raman laser tunable in the U-band and beyond. The Stokes wavelength is tuned in the 1631–1685 nm range when tuning a C-band pump laser in the 1520–1570 nm range. We also demonstrate switching between Raman lasing modes which corresponds to “jumps” by 2 or 3 whispering gallery modes (WGMs) while sweeping the pump laser near a certain WGM (without pump “jumps” between WGMs). In addition, four-wave mixing (FWM) leading to single mode anti-Stokes wave generation in the E-band near 1450 nm is obtained when the pump wavelength is near the microresonator zero dispersion wavelength (ZDW) and the phase matching condition for the pump, Stokes, and anti-Stokes waves is satisfied.