Widely Tunable Silicon Photonics Narrow-Linewidth Passband Filter Based on Phase-Shifted Waveguide Bragg Grating

A new approach for broad and efficient tuning of the narrow resonant transmission window in integrated phase-shifted Bragg gratings realized in silicon waveguides, suitable for the photonic processing of microwave signals, is proposed and demonstrated. The method exploits local micro-heaters (MHs) for the tuning of the resonant cavity formed by the insertion of a phase-shift section within a uniform Bragg grating structure. Two different MHs geometries have been investigated. Wide tuning ranges of the passband filter with a narrow linewidth of ~30 pm up to 7 nm, only limited by the BG stopband region width, for maximum MH absorbed power of ~11 mW are observed.