Waveguide lasers based on platforms of optical dielectric crystals

Abstract

Miniature light sources are desirable for integrated photonic devices. Dielectric crystals with diverse structures and functions are important media for various photonic and optical applications. Laser crystals serve as gain media for solid state laser systems, which have been applied for generation of wavelength bands from visible till mid-infrared. Direct processing of dielectric crystals by “physical” techniques, such as ion beam irradiation or femtosecond laser writing, has been successful used to produce waveguide structures in laser materials. The fabricated structures, with on-demand configurations, are good candidates to achieve highly efficient waveguide lasers towards compact light sources. In this work, we apply ion beam technology, including techniques of ion implantation, swift heavy ion irradiation, or proton beam writing, to microprocess the well-known laser crystals of Nd:YAG, producing low-loss waveguides with a few geometries. Other techniques like laser ablation and diamond blade dicing are applied to construct more complicated structures on the ion irradiated Nd:YAG platforms. Under optical pumps, efficient waveguide lasers operating in both continuous-wave (CW) and passively Q-switched regimes have been realized. The Q-switching of the waveguide laser systems is achieved by using the well-known nanomaterials, such as graphene, WS 2 , VO 2 , black phosphorous as saturable absorbers. The obtained lasers from the structures are with excellent features. For example, the proton beam written waveguide lasers are with beam diameter of only 2 µm. The shortest pulse duration at 1064nm in Q-switched system with VO 2 as saturable absorber is 700 ps in our Nd:YAG waveguide laser systems. Our work opens a way to develop high-quality waveguide laser systems for a number of photonic applications.