High confinement ion-exchanged waveguides for nonlinear applications

Abstract

Ion-exchange can be used to locally increase the refractive index of a glass, thus allowing the fabrication of optical waveguides. This technology has been used for decades to obtain passive and active devices. In particular, integrated Q-switched lasers have been recently achieved. The high optical power from pulsed lasers in combination with the light confinement of waveguides allows designing devices for nonlinear applications. For example, nonlinear phenomena is recognized as an essential mechanism of spectral broadening needed for the realization of supercontinuum laser sources. In this paper we investigate the power handling capabilities of waveguides made by ion-exchange. First, the fabrication technology based on the Ag+/Na+ exchange will be briefly presented for surface and buried waveguides. Both types of waveguides are then designed in order to minimize their effective area. These waveguides are fabricated, their damage threshold and effective area are characterized, 4.8±0.5μm2 and 14.2±1.4μm2 effective area are reached for surface and buried waveguides respectively. Their ability to handle high optical power density, 25±13GW/cm2 and 65±39GW/cm2 respectively is assessed and the main cause for optical damage in silver ion-exchanged waveguides is investigated.