Single Wavelength Resonator Based on $\pi$ Phase-Shifted Antisymmetric Bragg Grating

The principle, design, and characterization of a resonator on the silicon-on-insulator (SOI) platform based on the π phase-shifted antisymmetric Bragg grating (ASBG) are presented. With the aid of an asymmetric directional coupler (ADC), the resonance circuit between the two ASBGs is formed by the forward first-order transverse electric (TE
₁
) mode and the backward fundamental transverse electric (TE
₀
) mode. Only negligible amount of the backward TE
₀
mode can be coupled to the bus waveguide, which is different from the conventional Fabry-Perot (F-P) resonator. Compared with the widely used microring resonator, it can realize single wavelength resonance. The single resonance resonator with an extinction ratio of 20.0 dB and a quality factor (Q-factor) of 9888 has been experimentally demonstrated. Moreover, multiple wavelength resonances with a free spectrum range (FSR) of 0.63 nm is obtained when the phase shifter length is 200 μm.