Thermal release tape assisted mechanical exfoliation of pristine TMD and the performance of the exfoliated TMD saturable absorbers for Q-switched laser generation

Abstract

This research applied an enhanced material exfoliation and transfer mechanism to process various pristine transition metal dichalcogenide (TMD) materials into a few-layer structure. The mechanical exfoliation of the TMD materials was done using a thermal release tape (TRT) with a different adhesion property compared to the scotch tape (ST) commonly used in the conventional scotch tape assisted mechanical exfoliation (ST-ME) technique. The thermal release tape assisted mechanical exfoliation (TRT-ME) performs better than the ST-ME. Four pristine TMD saturable absorbers, including molybdenum disulfide (MoS2), tungsten disulfide (WS2), molybdenum diselenide (MoSe2), and tungsten diselenide (WSe2), have been fabricated using the TRT-ME technique. Subsequently, the performances of these materials were investigated using the same experimental systems and settings. These TMD materials were tested as saturable absorbers (SAs) to induce pulsed lasing in an Erbium-doped fiber laser (EDFL) cavity. The TRT-exfoliated TMD saturable absorbers were incorporated into the laser cavity by sandwiching in between two fiber ferrules using a fiber connector. Incorporating these saturable absorbers into the laser cavity has successfully induced promising Q-switching operations at the C-band region. Besides the pump power-dependent output performance, the stability and wavelength tunability of the Q-switched lasers were also studied at the maximum pump power. The findings from the studies show that the Q-switched lasers induced by the TRT-exfoliated pristine TMD saturable absorbers were stable and wavelength-tunable. In the context of Q-switched laser, the TRT-exfoliated WS2 has the best performance among other pristine saturable absorbers due to its ability to generate the highest pulse energy.