Experimental demonstration of quenched transmission effect of an ultrathin metallic grating.

We report on the experimental study of an anomalous transmission effect in ultrathin metallic gratings, where the metal thickness is much thinner than the skin depth. In particular, incident transverse magnetic polarized waves are reflected while incident transverse electric polarized waves are transmitted. This anomalous effect is strongly dependent on the metal thickness and metal width. We systematically investigate and demonstrate the anomalous effect and find the optimized nanostrip thickness and width by introducing a shadow-mask fabrication approach. Our results demonstrate the possibility of developing ultrathin nanostrip based planar metasurfaces with low loss.

Enhanced optical tuning of modified-geometry resonators clad in blue phase liquid crystals.

Active optical tuning of silicon racetrack resonators clad in dye-doped blue phase liquid crystals (BPLCs) is experimentally demonstrated. An adiabatic racetrack resonator geometry that allows for enhanced tuning is presented and analyzed. The resonance shift of an unmodified geometry racetrack is Δλ=0.7 nm, while an adiabatic racetrack achieves a Δλ=1.23 nm resonance shift because of a greater mode overlap with the cladding. The calculated refractive index change of the BPLC is Δn=0.0041 for both geometries.

Passive Temperature Stabilization of Silicon Photonic Devices Using Liquid Crystals.

In this work we explore the negative thermo-optic properties of liquid crystal claddings for passive temperature stabilization of silicon photonic integrated circuits. Photonic circuits are playing an increasing role in communications and computing, but they suffer from temperature dependent performance variation. Most existing techniques aimed at compensation of thermal effects rely on power hungry Joule heating. We show that integrating a liquid crystal cladding helps to minimize the effects of a temperature dependent drift. The advantage of liquid crystals lies in their high negative thermo-optic coefficients in addition to low absorption at the infrared wavelengths.

Optical tuning of silicon photonic structures with nematic liquid crystal claddings.

An analysis of and experimental demonstration of active optical tuning of silicon strip waveguides with methyl red doped nematic liquid crystal claddings is presented. Under low-power irradiation by polarized light, the reorientation of the nematic, the resulting index change, and phase shift produce a tuning range of 5.6 nm for the microresonator resonances.