Femtosecond-laser-written Tm:KLu(WO4)(2) waveguide lasers

Abstract

Depressed-index channel waveguides with a circular and photonic crystal cladding structures are prepared in a bulk monoclinic Tm:KLu(WO4)(2) crystal by 3D direct femto-second laser writing. The channel waveguide structures are characterized and laser operation is achieved using external mirrors. In the continuous-wave mode, the maximum output power of 46 mW is achieved at 1912 nm corresponding to a slope efficiency of 15.2% and a laser threshold of only 21 mW. Passive Q-switching of a waveguide with a circular cladding is realized using single-walled carbon nanotubes. Stable 7 nJ/50 ns pulses are achieved at a repetition rate of 1.48 MHz. This first demonstration of similar to 2 mu m fs-laser-written waveguide lasers based on monoclinic double tungstates is promising for further lasers of this type doped with Tm3+ and Ho3+ ions. (C) 2017 Optical Society of America