Femtosecond-Laser-Written S-Curved Waveguide in Nd:YAP Crystal: Fabrication and Multi-Gigahertz Lasing

Abstract

We report on the design and fabrication of straight and S-curved waveguides in neodymium-doped yttrium aluminate (Nd:YAP) crystal by using direct femtosecond laser writing. These S-curved channel waveguides are based on the hexagonal optical-lattice-like and depressed cladding geometry. For each type waveguide, S-curves with three lateral offsets of 50 µm, 100 µm, and 150 µm are implemented. These waveguides are with good guiding properties and low bending losses. With S-curved waveguide as laser cavity, dual-wavelength, 31.6 GHz waveguide laser operating at 1064 nm and 1079 nm have been demonstrated based on MoS 2 as a saturable absorber. This work paves the way to develop new on-chip ultrafast laser sources based on femtosecond laser inscribed S-curved waveguides.

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

“…[1,2] In addition to straight channels, on-demand curveshaped channel WGs based on fs-DLW have been demonstrated and provide significant potential for diverse functional optical elements. [3,4] Beam-splitter-type (BS) WGs fabricated by fs-DLW are used not only in passive devices, [5,6] but also for continuous-wave (cw) laser operation in the 1 [7][8][9] and 2 μm [10] wavelength range. Such BS WG lasers providing multiple lasing output signals from a single pump could be utilized in quantum optics, optical sensing, and communication applications.…”

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)].…”

“…For instance, 6.5 GHz Q-switched mode-locked (QML) lasers have been demonstrated in a femtosecond laser-written Nd∶YVO 4 cladding waveguide using 2D materials as the saturable absorber. 202 Another recent sample is Nd:YAP crystal : 31.6-GHz QML lasers have been demonstrated in an S-curved waveguide, 159 as shown in Fig. 13(f).…”

Femtosecond Laser Precision Engineering: From Micron, Submicron, to Nanoscale

“…The femtosecond laser is also able to create arbitrary structures inside crystals. Chen et al successfully achieved S-curved channel waveguides with a low bending loss using femtosecond laser irradiation of hexagonal optical latticelike waveguide and depressed cladding structures [90]. Such waveguides fabricated in the crystal are used to realize double wavelengths (1064 and 1079 nm) curved waveguide laser with a repetition rate of 31.6 GHz, pulse duration of 16 ps, and maximum signal to noise ratio of 49 dB.…”