Efficient Resonance Management in Ultrahigh-Q 1D Photonic Crystal Nanocavities Fabricated on 300 mm SOI CMOS Platform

Abstract

Photonic crystal (PhC) nanocavities have demonstrated unique capabilities in terms of light confinement and manipulation. As such, they are becoming attractive for developing novel resonance-based photonic integrated circuits (PICs). Here two essential challenges arise however-how to realize ultrahigh quality factor (Q) PhC cavities using standard fabrication processes compatible with large volume fabrication, and how to efficiently integrate them with existing building blocks. In this work, ultrahigh-Q one-dimensional (1D) PhC nanocavities fabricated on a 300 mm silicon-on-insulator wafer are demonstrated by optical lithography, with a record Q factor of up to 0.84 million. Moreover, efficient mode management in those cavities is shown by coupling them with an access waveguide, realizing two critical components: notch filters and narrow-band reflectors. In particular, they allow both single-wavelength and multi-wavelength operation, at the desired resonant wavelengths, over a broad wavelength range (>100 nm). Compared to traditional cavities, this offers a fantastic strategy for implementing resonances precisely in PIC designs with more freedom in terms of wavelength selectivity and the control of mode number. Given their compatibility with optical lithography and compact footprint, the realized 1D PhC nanocavities will be of profound significance for designing compact and novel resonance-based photonic components on large scale.