Efficient resonance management in ultrahigh-Q one-dimensional photonic crystal nanocavities fabricated on 300 mm SOI CMOS platform

Photonic crystal (PhC) nanocavities have demonstrated unique capabilities in terms of light confinement and manipulation. As such, they are becoming attractive for the design of novel resonance-based photonic integrated circuits (PICs). Here two essential challenges arise however - how to realize ultrahigh-Q PhC cavities using standard fabrication processes compatible with large volume fabrication, and how to efficiently integrate them with other standard building blocks, available in exiting PIC platforms. In this work, we demonstrate ultrahigh-Q 1D PhC nanocavities fabricated on a 300 mm SOI wafer by optical lithography, with a record Q factor of up to 0.84 million. Moreover, we show efficient mode management in those oxide embedded cavities by coupling them with an access waveguide and realize 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, while suppressing all other 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.