Carbon nanotube Q-switched Yb:KLuW surface channel waveguide lasers
A channel waveguide (WG) buried immediately below the surface of a Yb:KLuW crystal is used as a laser gain medium for passive 𝑄-switching by both evanescent- and direct-field interactions with single-walled carbon nanotubes (SWCNTs) near 1040 nm. The SWCNTs used as saturable absorbers (SAs) are deposited on top of the half-ring-type channel WG fabricated via femtosecond direct laser writing. The 𝑄 -switched WG laser delivers 88.5 ns pulses at a 1.16 MHz repetition rate with a maximum average output power of 680 mW. For the two different interaction schemes with SWCNT-SAs, the pulse characteristics, depending on the output coupling ratio and absorbed pump power, are experimentally investigated and compared to the results of theoretical analyses of the SA 𝑄-switched operation. ; National Research Foundation of Korea (2017R1A4A1015426, 2018H1A2A1061480); Spanish Government (FIS2017-87970-R, MAT2016-75716-C2-1-R (AEI/FEDER, UE)); Junta de Castilla y León (SA287P18); Generalitat de Catalunya (2017SGR755).
