Femtosecond laser micromachining of waveguides in silicone-based hydrogel polymers

Abstract
By tightly focusing 27fs laser pulses from a Ti:sapphire oscillator with 1.3nJ pulse energy at 93MHz repetition rate, we are able to fabricate optical waveguides inside hydrogel polymers containing 36% water by weight. A tapered lensed fiber is used to couple laser light at a wavelength of 632.8nm into these waveguides within a water environment. Strong waveguiding is observed due to large refractive index changes. A large waveguide propagation loss is found, and we show that this is caused by surface roughness which can be reduced by optimizing the waveguides.