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Diamond slotted photonic crystal (PhC) cavities were fabricated and used for gas detection. They exhibit wavelength sensitivity reaching a 350 nm per unit change of the refractive index of the gaseous environment of the PhC. With a simple oxidized surface termination, diamond PhCs display an ultrahigh sensitivity to the surface adsorption of polar molecules. Gaseous concentrations as low as 80 parts per million (ppm) of hexanol vapor in nitrogen are probed, and a detection limit in the ppm range is inferred, demonstrating a high interest of such devices for trace sensing.

We present a simple method to accurately measure the effective thermal resistance of a photonic crystal microcavity. The cavity is embedded between two Schottky contacts forming a metal-semiconductor-metal device. The photocarriers circulating in the device provide a local temperature rise that can be dominated by Joule effect under certain conditions. We show that the effective thermal resistance (R_th) can be experimentally deduced from the spectral shift of the cavity resonance wavelength measured at different applied bias. We deduce a value of R_th=1.6×10^4  KW^−1 for a microcavity on silicon-on-insulator, which is in good agreement with 3D thermal modeling by finite elements.

The spatial distribution of photon modes confined in a 0D cavity and a 1D W1 waveguide is investigated on AlN-based photonic crystal (PC) membranes by spectrally resolved scanning confocal microscopy in the ultra-violet spectral range. The influence of the fabrication-induced disorder of the PC on the photon modes is analyzed. The cavity modes are shown to be robust with respect to disorder, whereas the 1D modes of the W1 waveguide are localized near its cut-off frequency. Those modifications of the lowest energy photonic modes are compared to simulations of weakly disordered photonic structures.

Processing of group III-nitride materials such as AlN in the form of photonic crystals or microdiscs opens new perspectives for basic cavity quantum electrodynamic studies or the development of novel devices operating in the ultra-violet range. These devices can be either passive or active by embedding self-assembled GaN quantum dots. We review the recent progress achieved in the field of nitride-based microresonators for UV nanophotonics.