Q-switched operation of a pulsed-laser-deposited Yb:Y_2O_3 waveguide using graphene as a saturable absorber

Abstract

The first, to the best of our knowledge, Q-switched operation of a pulsed-laser-deposited waveguide laser is presented. A clad Yb:Y(2)O(3) waveguide was Q-switched using an output coupling mirror coated with a single layer of graphene deposited by atmospheric pressure chemical vapor deposition. During continuous-wave operation, a maximum power of 83 mW at a slope efficiency of 25% was obtained. During Q-switched operation, pulses as short as 98 ns were obtained at a repetition rate of 1.04 MHz and a central wavelength of 1030.8 nm.

456-mW graphene Q-switched Yb:yttria waveguide laser by evanescent-field interaction

“…Better heat removal from the waveguide should allow stabilized operation at different power levels. No damage to the graphene was observed at such high pump powers and an improvement of more than 25 times in average power and pulse energy was observed when compared to previous work using end-butted graphene [14] demonstrating the capability of evanescent-field interaction with graphene for high-power operation.…”

“…This was achieved at an absorbed pump power of 4.1 W using a Yb:Y2O3 planar waveguide, without damage to the graphene SA as previously encountered with an in-line graphene SA [14].…”

“…We recently reported the Q-switched operation of a PLD-grown Yb:Y2O3 waveguide using a graphene-covered output coupler acting as a SA [14]. However, the output power of this laser was limited by damage to the graphene layer, which was in the path of the laser beam.…”

“…When compared to a Yb:Y2O3 waveguide laser [14] which was Q-switched with graphene end-butted on the waveguide and pumped by one single-mode diode, the pulse energy is found to have increased by more than 6 times, demonstrating the advantage of the evanescent-coupled graphene-covered waveguides for higher power operation. Also, due to the quasi-monolithic cavity configuration, there was no decrease in the performance due to misalignment of the mirror or the waveguide [24] as was observed in [14]. The measured mode profile is shown in the inset of figure 3 (a) and the 4σ mode diameter was found to be 9 µm in the guided direction.…”

Graphene Q-switched Yb:KYW planar waveguide laser

“…The operation of waveguide lasers Q-switched or mode-locked using SESAMs and other SAs based on Cr-doped crystals, carbon nanotubes and graphene has been demonstrated. [22][23][24][25][26][27][28][29][30] In most cases, however, a direct interaction scheme of light with the SAs, i.e., placing the SA perpendicular to the resonator axis, was employed. To reduce the damage susceptibility and thermal load of SAs, indirect interaction by evanescent-field coupling was recently suggested for Q-switching and mode-locking.…”