Thin film selenide glasses have emerged as an important material for integrated photonics due to its high refractive index, mid-IR transparency and high non-linear optical indices. We prepared high-quality As 2 Se 3 glass films using spin coating from ethylenediamine solutions. The physio-chemical properties of the films are characterized as a function of annealing conditions. Compared to bulk glasses, as-deposited films possess a distinctively different network structure due to presence of Se-Se homopolar bonds and residual solvent. Annealing partially recovers the As-Se 3 pyramid structure and brings the film refractive indices close to the bulk value. Optical loss in the films measured at 1550 nm wavelength is 9 dB/cm, which was attributed to N-H bond absorption from residual solvent.

This paper reports a versatile, roll-to-roll and backend compatible technique for the fabrication of high-index-contrast photonic structures on both silicon and plastic substrates. The fabrication technique combines low-temperature chalcogenide glass film deposition and resist-free singlestep thermal nanoimprint to process low-loss (1.6 dB/cm), sub-micron single-mode waveguides with a smooth surface finish using simple contact photolithography. Using this approach, the first chalcogenide glass micro-ring resonators are fabricated by thermal nanoimprint. The devices exhibit an ultra-high quality-factor of 4 × 10 5 near 1550 nm wavelength, which represents the highest value reported in chalcogenide glass micro-ring resonators. Furthermore, sub-micron nanoimprint of chalcogenide glass films on non-planar plastic substrates is demonstrated, which establishes the method as a facile route for monolithic fabrication of high-index-contrast devices on a wide array of unconventional substrates.

Integrated photonics provides a miniaturized and potentially implantable platform to manipulate and enhance the interactions between light and biological molecules or tissues in in-vitro and in-vivo settings, and is thus being increasingly adopted in a wide cross-section of biomedical applications ranging from disease diagnosis to optogenetic neuromodulation. However, the mechanical rigidity of substrates traditionally used for photonic integration is fundamentally incompatible with soft biological tissues. Cytotoxicity of materials and chemicals used in photonic device processing imposes another constraint towards these biophotonic applications. Here we present thin film TiO2 as a viable material for biocompatible and flexible integrated photonics. Amorphous TiO2 films were deposited using a low temperature (<250 °C) sol-gel process fully compatible with monolithic integration on plastic substrates. High-index-contrast flexible optical waveguides and resonators were fabricated using the sol-gel TiO2 material, and resonator quality factors up to 20,000 were measured. Following a multi-neutral-axis mechanical design, these devices exhibit remarkable mechanical flexibility, and can sustain repeated folding without compromising their optical performance. Finally, we validated the low cytotoxicity of the sol-gel TiO2 devices through in-vitro cell culture tests. These results demonstrate the potential of sol-gel TiO2 as a promising material platform for novel biophotonic devices.

In this paper, we quantitatively analyzed the tradeoff between energy per bit for switching and modulation bandwidth of classical electrooptic modulators. A formally simple energybandwidth limit (10) is derived for electrooptic modulators based on intracavity index modulation. To overcome this limit, we propose a dual cavity modulator device which uses a coupling modulation scheme operating at high bandwidth (>200 GHz) not limited by cavity photon lifetime and simultaneously features an ultralow switching energy of 0.26 aJ, representing over three orders of magnitude energy consumption reduction compared to state-of-the-art electrooptic modulators.

Understanding radiation damage is of significant importance for devices operating in radiation-harsh environments. In this Letter, we present a systematic study on gamma radiation effects in amorphous silicon and silicon nitride guided wave devices. It is found that gamma radiation increases the waveguide modal effective indices by as much as 4×10^-3 in amorphous silicon and 5×10^-4 in silicon nitride at 10 Mrad dose. This Letter further reveals that surface oxidation and radiation-induced densification account for the observed index change.