Abstract

Compact pulsed laser sources are of interest for diverse application areas. Due to their broad gain bandwidth, high Stokes efficiency and low thermal load near the 1 μm spectral region, ytterbium doped laser materials are promising for such devices. Channel waveguides in such gain media provide compact laser systems and deliver efficient single-mode laser operation with low laser thresholds. One of the widely-used techniques for manufacturing channel waveguides in transparent materials including laser gain media is fs-laser inscription. Inscribing two parallel tracks inside a laser crystal with a distance of few 10 µm allows for highly efficient laser operation in few mm-long monolithic resonators [1]. Pulsed operation of fs-laser inscribed channel waveguide lasers has been demonstrated with saturable absorbers (SAs) including SESAMs and low-dimensional carbon nanostructures. Intrinsic fast response time, linear and nonlinear absorption in a broad spectral range and relatively simple fabrication processes make graphene and single-walled carbon nanotubes (SWCNTs) a cost effective approach for saturable absorbers for various laser types including channel waveguide lasers. Recently, Q-switched [2-4] and even mode-locked operation at 1.94 GHz repetition rate [5] have been demonstrated with fs-laser inscribed Yb³⁺-doped waveguides. However, mode locking of fs-laser inscribed waveguide lasers by employing carbon nanotubes is not yet reported.

© 2017 IEEE