Highly efficient coupling between a monolithically integrated photonic crystal cavity and a bus waveguide

We experimentally demonstrate a new optical filter design comprising of a photonic crystal cavity and a low index bus waveguide which are monolithically integrated on a silicon-on-insulator (SOI) platform. We have fabricated oxide clad PhC cavities with a silicon nitride waveguide positioned directly above, such that there is an overlap between the evanescent tails of the two modes. We have realised an extinction ratio of 7.5dB for cavities with total Q of 50,000.Postprin

Novel Dispersion-Adapted Photonic Crystal Cavity With Improved Disorder Stability

We present a photonic crystal cavity (PhCC) design methodology that is based on systematically engineering the dispersion curve of a PhC line-defect. Our combined numerical and analytical approach offers the option of using a variety of different defect modifications to create a gentle-confinement cavity with a Gaussian profile. Here, we demonstrate the principle of the method by employing relatively large hole-shifts (tens of nanometers), aiming for improved stability against disorder. Such improved stability compared with the established hetero-structure design approach is then experimentally confirmed on cavities fabricated in silicon. We point out some design features that are linked to this improved disorder stability. In addition, we note that different types of cavities exhibit dissimilar fabrication-limited Q-factors despite identical fabrication process

Low-power continuous-wave generation of visible harmonics in silicon photonic crystal nanocavities

We present the first demonstration of frequency conversion by simultaneous second- and third-harmonic generation in a silicon photonic crystal nanocavity using continuous-wave optical excitation. We observe a bright dual wavelength emission in the blue/green (450-525 nm) and red (675-790 nm) visible windows with pump powers as low as few microwatts in the telecom bands, with conversion efficiencies of $10textminus5/W and$10/W2 for the second- and third-harmonic, respectively. Scaling behaviors as a function of pump power and cavity quality-factor are demonstrated for both second- and third order processes. Successful comparison of measured and calculated emission patterns indicates that third-harmonic is a bulk effect while second-harmonic is a surface-related effect at the sidewall holes boundaries. Our results are promising for obtaining practical low-power, continuous-wave and widely tunable multiple harmonic generation on a silicon chip