Pedestal disk resonator in potassium yttrium double tungstate

Abstract

Rare earth ion doped potassium double tungstates (e.g. KY(WO 4) 2 , KYb(WO 4) 2 , and KGd(WO 4) 2) have long been used as laser and amplifier materials thanks to the high achievable gain provided by the rare-earth ions. This family of host materials is also very attractive for nonlinear optics due to their high nonlinear refractive index and Raman gain. Very efficient on-chip solid state lasers, frequency combs, supercontinuum sources and Raman lasers could be realized if highrefractive index waveguides with the correct dispersion were developed. To date, the demonstrated integrated devices in rare-earth ion doped potassium double tungstates have shown very promising results, including high gain in on-chip amplifiers and high efficiency and output power in on-chip lasers. These devices, however, were fabricated using low refractive index contrast waveguides, which are not suitable for ring resonators or to achieve anomalous dispersion. High refractive index contrast KY(WO 4) 2 waveguides with high confinement are therefore needed as building blocks for active devices. In this work, pedestal disk resonators are proposed, based on a combination of swift ion irradiation, focused ion beam milling and a novel wet etching process. In-coupling of light into the first fabricated pedestal disks will be presented.

Pedestal microdisks in potassium yttrium double tungstate

“…The higher thickness of this segment suggests that the etching step was not self-terminated, and amorphous material is still present. However, calculations show that any under-etch above 4 µm is more than sufficient to have a highly confined mode in the outer rim of the microdisk at an operation wavelength of 1550 nm [35].…”