As part of the requirements for a compact pulsed coherent source, solid-state waveguide lasers have been extensively investigated as a low-gain, low-lasing threshold, and a cost-effective solution with significant potential as a future on-chip integrated light source. The direct application of the evanescent field interaction scheme to the waveguide gain provides a much more simple, compact, robust, and integrated platform for the pulsed operation of solid-state waveguide laser. To use the evanescent field interaction scheme, a saturable absorber that can be simply deposited on the waveguide is needed due to the difficulty of the epitaxy of the semiconductor based saturable absorber on the top side of the monolithic waveguide gain.
In this thesis, the pulsed operation of a solid-state Yb:KYW planar waveguide lasers is researched with nanocarbon materials. We first achieve a stable Q-switched operation of the Yb:KYW planar waveguide laser by evanescent field interaction with nanocarbons for the first time. Carbon nanotubes and graphene are deposited on a top side of the Yb:KYW planar waveguide, respectively, and facilitate the Q-switching of the Yb:KYW planar waveguide laser. A comparative analysis of direct and evanescent field interaction schemes is subsequently conducted at various positions of the carbon nanotube saturable absorber, such as an output coupler, an end mirror, and on a top side of the planar waveguide. Each case exhibits stable Q-switched operation, and it was confirmed that the maximum intensity at the saturable absorber of the evanescent field interaction scheme is 1,000 times lower than that of direct field interaction scheme of the end mirror. Moreover, a mode-locked operation for the solid-state Yb:KYW planar waveguide laser is proposed. To fulfill the cw mode-locking conditions, an extended cavity configuration is adopted and the carbon nanotube saturable absorber is deposited on the output coupler. The laser exhibited stable cw mode-locked operation.
