2-μm wavelength-switchable Tm/Ho composite laser

Abstract We demonstrated a 2-μm wavelength-switchable Tm/Ho composite laser employing a compact hybrid cavity with changeable output couplers, which facilitates the direct use of common 800 nm diode lasers for separated Tm laser and Ho laser from a single bulk composite gain medium and can work in both continuous wave (CW) and Q-switching manners. With the broad band coated output couplers, maximum CW power of 1.12 W and shortest passively Q-switched (PQS) pulses with a width of 15.7 ns under a repetition frequency of 6.7 kHz were obtained in pure Tm laser at 2011 nm. With the narrow-band coated output couplers, maximum CW power of 1.04 W and shortest PQS pulse of 118 ns under repetition rate of 10.5 kHz were obtained in pure Ho laser at 2091 nm. Combing both advantages of Tm laser and Ho laser, a wide scope of applications including detection, commutation, and medical treatments are expected from the proposed laser source due to its accessibility, multifunction and miniaturization.