Controllable Dynamic Single‐ and Dual‐Channel Graphene Q‐Switching in a Beam‐Splitter‐Type Channel Waveguide Laser

Abstract

Direct inscription of structures by femtosecond-laser pulses facilitates the flexible fabrication of diverse optical channel waveguides in dielectric laser gain media. Among them, beam-splitter-type waveguide lasers have been recently studied; however, there is a lack of investigations on the effect of unique characteristics of such waveguides, such as controlled splitting ratios of output powers and selectable excitation of individual channels, for pulsed laser operation. Here, dynamic single-and dual-channel graphene Q-switching of an Yb:YAG waveguide consisting of one input and two output channels is demonstrated by controlling the power-splitting ratio. Single-channel Q-switched operation, exhibiting typical Q-switched pulses, is achieved by interaction between the graphene saturable absorber and the desired one of the two channels. When both channels exceed the Q-switching threshold, dual-channel Q-switching generates a pulse train that simultaneously combines the separately Q-switched pulses induced from each channel under excitation with a single pump source. At a fixed power-splitting ratio, the pulsed mode can be dynamically switched between the single-and dual-channel Q-switched operations by varying the pump power. The beam-splitter-type waveguide laser demonstrated in this study can be further developed for multiple-channel Q-switching, high-repetition-rate mode-locking, and on-chip dual-comb sources advantageous for diverse applications in optical communication, metrology, and sensing.

Selective 1.3 μm Laser Emission via Coupled Microlaser for Laser Resonance Tuning

“…Figure 2d shows the measured transmission spectrum of D 29 using the same method as D39. Due to its thin thickness, only TE mode light can be supported by D 29 . The FSR between TE 86,01 and TE 85,01 is 14.8 nm, and the Q factor of TE 86,01 is 1.01 × 10 5 .…”

“…However, these materials are not the most optimal choice for achieving high conversion efficiency as gain media. In contrast, the widely adopted and successful gain medium in well-established solid-state bulk lasers, rare-earth-doped yttrium aluminum garnet (YAG) crystal, − emerges as an ideal choice for future WGM lasers.…”

Femtosecond laser-inscribed optical waveguides in dielectric crystals: a concise review and recent advances

“…Beyond a normal straight laser cavity, it is also possible to achieve efficient optical feedback for lasing oscillation in curved and branched cavity geometry owing to an enhanced optical gain of a waveguide laser. For example, in femtosecond laser-written 3D structures, compact waveguide lasers at 1 μm have been proposed in different functionalities, such as S-curved, 159,194 Y-branches, 97,180,208,216 1 × 2 and 1 × 4 beam splitting, 101 ring-shaped beam transformation, 100,132 and optical-lattice-like lasing 75 [Figs. 13(a)-13(e)].…”

Tenability and improvement of the structural, electronic, and optical properties of lead-free CsSnCl3perovskite by incorporating reduced graphene oxide (rGO) for optoelectronic applications

“…27 The low dimensional structures, such as carbon nanotubes and graphene, are successfully acknowledged as suitable saturable absorbers for passive Q-switching mode. 28 This paper considers an energy conversion from the pump laser field to the surface plasmon polaritons. 29 The rGO-based nanocomposite is an effective way to load the semiconductor nanoparticles on the graphene sheet with no further aggregation and stacking of the graphene sheet.…”