Open AccessUltrafast laser inscribed waveguide lasers in Tm:CALGO with depressed-index cladding
Author(s) -
Víctor Llamas,
Pavel Loiko,
Esrom Kifle,
Carolina Romero,
Javier R. Vázquez de Aldana,
Zhongben Pan,
Josep María Serres,
Hualei Yuan,
Xiaojun Dai,
Huaqiang Cai,
Yicheng Wang,
Yongguang Zhao,
V. K. Zakharov,
А. В. Вениаминов,
Romain Thouroude,
Mathieu Laroche,
H. Gilles,
Magdalena Aguiló,
Francesc Dı́az,
Uwe Griebner,
Valentín Petrov,
Patrice Camy,
Xavier Mateos
Publication year - 2020
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.384258
Subject(s) - materials science , laser , optics , cladding (metalworking) , laser power scaling , slope efficiency , laser pumping , raman spectroscopy , femtosecond , waveguide , fiber laser , refractive index , optoelectronics , physics , metallurgy
Depressed-index buried and surface channel waveguides (type III) are produced in a bulk 3.5 at.% Tm 3+ :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 ( 3 H 6 → 3 F 4 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 ( 3 H 6 → 3 H 4 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 Tm 3+ :CALGO waveguides for mode-locked laser operation at ∼2 µm.