Watt-level ultrafast laser inscribed thulium waveguide lasers. (August 2020)

• Record Type: Journal Article
• Authors: Kifle, Esrom; Loiko, Pavel; Romero, Carolina; Vázquez de Aldana, Javier Rodríguez; Aguiló, Magdalena; Díaz, Francesc; Camy, Patrice; Griebner, Uwe; Petrov, Valentin; Mateos, Xavier
• Is Part Of: Progress in quantum electronics. Volume 72(2020)
• Publication Date: 2020-08
• Subjects: Quantum electronics -- Periodicals; Électronique quantique -- Périodiques; 537.5
• DOI: 10.1016/j.pquantelec.2020.100266
• Languages: English
• ISSNs: 0079-6727

Abstract

Abstract: We report on the first watt-level ultrafast laser inscribed Thulium waveguide (WG) lasers. Depressed-index buried channel WGs with a circular cladding (type III) are produced in monoclinic Tm 3+ :KLu(WO4 )2 crystals. Laser operation is achieved under conventional ( 3 H6 → 3 H4 ) and in-band ( 3 H6 → 3 F4 ) pumping. In the former case, employing a Raman fiber laser emitting at 1679 ​nm as pump, the continuous-wave Tm channel WG laser generated 1.37 ​W ​at 1915–1923 ​nm with a record-high slope efficiency of 82.7% (with respect to the absorbed pump power), a threshold of only 17 ​mW and a spatially single-mode output with linear polarization. The WG propagation losses were 0.2 ​± ​0.3 ​dB/cm. Passive Q-switching of Tm channel WG lasers is achieved using Cr 2+ :ZnS and Cr 2+ :ZnSe saturable absorbers. With Cr 2+ :ZnS, record-short pulses of 2.6 ns/6.9 ​μJ ​at a repetition rate of 8.0 ​kHz were generated. The developed WGs are promising for compact GHz mode-locked lasers at ~2 ​μm.