S.P. Watts

Single-mode direct-ultraviolet-written channel waveguide laser in neodymium-doped silica on silicon

A waveguide laser with a neodymium-doped silica core is fabricated on a silicon substrate by a combination of flame hydrolysis deposition, solution doping, and direct UV writing. The neodymium-ion concentration is estimated to be approximately 8000 parts in 10(5). The propagation loss around 1.05 microns is < 0.8 dB/cm. Lasing in the range 1048-1056 nm and 1356 +/- 1 nm is observed. A slope efficiency of 33% for a high-reflectivity output coupler and a threshold of 4 mW of absorbed power for a 25% output coupler are measured for the 4F3/2-->4I11/2 transition.

Assessment of waveguide thermal response by interrogation of UV written planar gratings

The technique of direct grating writing, based on direct ultraviolet writing, is demonstrated as a tool for highly accurate measurement of waveguide and material properties. Silica-on-silicon planar samples are processed using hydrogen loading and thermal locking before Bragg channel waveguides are defined in the photosensitive core layer. The refractive index is accurately probed to compare different thermal locking procedures and characterize waveguide thermal stability.

Directly UV-written planar channel waveguides containing simultaneously defined Bragg gratings

A new technique for the simultaneous writing of channels and Bragg gratings uses interfering focused UV beams in a photosensitive silica layer and is able to fabricate near-ideal Bragg gratings, with 60% reflectivity.

Single-step definition of channel waveguides with integral Bragg gratings in germanosilica-on-silicon wafers by direct UV writing

We present a single-step technique for defining channel waveguides with internal Bragg gratings in photosensitive germanosilica-on-silicon using two interfering focussed UV beams. Early devices exhibit reflection intensities of 80% with <0.15 nm bandwidth.