Femtosecond laser-induced apodized Bragg grating waveguides

We report on the inscription of apodized Bragg grating waveguides (BGWs) in fused silica using a modulated high repetition rate fs laser system. Tailoring of the grating's coupling strength is facilitated by appropriately substructuring the modulation of the inscribing laser radiation. The proposed alteration delivers an unchanged constant mean refractive index entailing homogeneous guiding properties along the entire waveguide. The BGWs fabricated using a Gaussian apodized modulation profile exhibit a 10 dB improvement in sideband suppression compared to waveguide gratings written with a uniform modulation profile.