Low-loss fs-laser-written surface waveguide lasers at >2 µm in monoclinic Tm3+:MgWO4

Abstract

[EN]Surface channel waveguides (WGs) based on a half-ring (40–60-µm-diameter) depressed-index cladding (type III) geometry are fabricated in monoclinic Tm3+:MgWO4 by femtosecond (fs) laser writing at a repetition rate of 1 kHz. The WGs are characterized by confocal laser microscopy and 𝜇-Raman spectroscopy. A Tm3+:MgWO4 WG laser generates 320 mW at ∼2.02µm with a slope efficiency of 64.4%. The WG emits a transverse single-mode and linear polarization (𝐸||𝑁𝑚). A remarkable low loss of <0.1dB/cm is measured for the WG. Vibronic laser emission at ∼2.08µm is also achieved.