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 substruc-turing 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.