Planar waveguide fabrication can be put into practice through techniques falling into two broad categories: modification of the refractive index of a bulk material (such as proton- or ion-exchange, ion-diffusion, ion-implantation, or laser writing) or layering/structuring materials with different refractive indices to fabricate composite structures (epitaxial processes, pulsed laser deposition). Finding the appropriate technique for waveguide fabrication is crucial in order to minimize propagation passive optical losses in small volumes of waveguide and to reach efficient lasing in the PWL.
This Optics Letters article by Ren et al. reports Nd:YCOB optical waveguide fabrication through the use of ultralow fluence Ar-ion implantation. The combination of appropriate materials and an optimal technique allowed a considerable decrease in the cavity propagation losses as well as the achievement of PWL lasing with a slope efficiency as high as ~68% for the fundamental wavelength, which is quite close to the Stokes efficiency limit of 76% for neodymium lasers pumped at 808 nm.
Due to the high optical non-linearity of YCOB crystals, this material can also be used for frequency self-doubling, where the processes of fundamental wavelength lasing and its conversion to second harmonic occur within the same medium. This benefit, i.e. a monolithic design using one crystal, might be crucial for the optical stability of the resulting integrated optical microdevices. Therefore, to take full advantage of this achievement, the authors should continue this research to obtain self-frequency doubling in the fabricated PWL.
You must log in to add comments.