Selective tuning of high-Q silicon photonic crystal nanocavities via laser-assisted local oxidation

TL;DR

This paper demonstrates a method for tuning high-Q silicon photonic crystal nanocavities using laser-assisted local oxidation, achieving significant resonance shifts with controlled Q-factor reduction, supported by numerical modeling.

Contribution

It introduces a laser-assisted local oxidation technique for precise resonance tuning of high-Q silicon photonic cavities, with detailed modeling of temperature effects and resonance shifts.

Findings

Achieved up to 8.7 nm resonance shift

Q-factor decreased from 3.2×10^5 to 1.2×10^5

Tuning process follows a parabolic rate law

Abstract

We examine the cavity resonance tuning of high-Q silicon photonic crystal heterostructures by localized laser-assisted thermal oxidation using a 532 nm continuous wave laser focused to a 2.5 mm radius spot-size. The total shift is consistent with the parabolic rate law. A tuning range of up to 8.7 nm is achieved with ~ 30 mW laser powers. Over this tuning range, the cavity Q decreases from 3.2\times10^5 to 1.2\times10^5. Numerical simulations model the temperature distributions in the silicon photonic crystal membrane and the cavity resonance shift from oxidation.