A grating-assisted microring resonator for wideband filtering

Abstract

In this paper, a silicon-based wideband filter with a high sidelobe suppression is proposed. The filer comprises a microring resonator (MRR) with a single ring with a Bragg grating. The Bragg grating in a microring is formed by a subwavelength grating (SWG) waveguide consisting of two gratings of the same period but with different filling-factors to induce variation in refractive index towards the direction of the propagation. The proposed wideband filter using grating-assisted MRR has a 3-dB bandwidth of 1.0734 THz at the passband. A sidelobe suppression of 19.79 dB for passband filtering, low insertion loss of <0.6 dB, a low in-band ripple of less than 0.2 dB are obtained. The proposed scheme uses only one microring; hence, it is compact in size. The proposed filter is a promising candidate for optical communication systems such as coarse wavelength division multiplexing and other wideband applications.