Ultrafast laser inscribed waveguide lasers in Tm:CALGO with depressed-index cladding

Identifier:  imarina:6090543

Handle: https://hdl.handle.net/20.500.11797/imarina6090543

Authors:  Llamas, V; Loiko, P; Kifle, E; Romero, C; de Aldana, JRV; Pan, ZB; Serres, JM; Yuan, HL; Dai, XJ; Cai, HQ; Wang, YC; Zhao, YG; Zakharov, V; Veniaminov, A; Thouroude, R; Laroche, M; Gilles, H; Aguiló, M; Díaz, F; Griebner, U; Petrov, V; Camy, P; Mateos, X

Abstract:
© 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement Depressed-index buried and surface channel waveguides (type III) are produced in a bulk 3.5 at.% Tm3+:CALGO crystal by femtosecond direct-laser-writing at kHz repetition rate. The waveguides are characterized by confocal microscopy and µ-Raman spectroscopy. Under in-band-pumping at 1679 nm (3H6 → 3F4 transition) by a Raman fiber laser, the buried channel waveguide laser with a circular cladding (diameter: 60 µm) generated a continuous-wave output power of 0.81 W at 1866-1947 nm with a slope efficiency of 71.2% (versus the absorbed pump power) and showed a laser threshold of 200 mW. The waveguide propagation losses were as low as 0.3 ± 0.2 dB/cm. The laser performance under in-band pumping was superior compared pumping at ∼800 nm (3H6 → 3H4 transition), i.e., the convetional pump wavelength. Vibronic laser emission from the WG laser above 2 µm is also achieved. The low-loss behavior, the broadband emission properties and good power scaling capabilities indicate the suitability of Tm3+:CALGO waveguides for mode-locked laser operation at ∼2 µm.