Comparative study of Yb:KYW planar waveguide lasers Q-switched by direct- and evanescent-field interaction with carbon nanotubes

Identifier:  imarina:4213860

Handle: https://hdl.handle.net/20.500.11797/imarina4213860

Authors:  Kim, Jun Wan; Choi, Sun Young; Bae, Ji Eun; Kim, Mi Hye; Jeong, Young Uk; Kifle, Esrom; Mateos, Xavier; Aguilo, Magdalena; Diaz, Francesc; Griebner, Uwe; Petrov, Valentin; Kim, Guang-Hoon; Rotermund, Fabian

Abstract:
© 2019 Optical Society of America. Both direct- and evanescent-field interactions with carbon nanotubes (CNTs) are applied to achieve stable Q-switched operation of Yb:KYW planar waveguide lasers. The performance characteristics were investigated in a same cavity configuration and analyzed in detail in the following three cases, CNTs deposited onto end mirror (M-coating), output coupler (OC-coating) and top surface of the planar waveguide (WG-coating). Maximum output powers, repetition rates, and minimum pulse durations are 61 mW, 1103 kHz and 215 ns for OC-coating, 39 mW, 1052 kHz and 275 ns for WG-coating, and 26 mW, 1119 kHz and 217 ns for M-coating, respectively. From the calculation of the configuration-dependent stability range, the beam size and the electric field distribution in the Yb:KYW planar waveguide, it is confirmed that the evanescent-field interaction scheme makes stable Q-switching possible with much lower intensities at saturable absorber compared to the direct-field interaction scheme in the presented waveguide laser operation.