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© COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only. Novel optical materials capable of advanced functionality in the infrared will enable optical designs that can offer lightweight or small footprint solutions in both planar and bulk optical systems. UCF's Glass Processing and Characterization Laboratory (GPCL) with our collaborators have been evaluating compositional design and processing protocols for both bulk and film strategies employing multi-component chalcogenide glasses (ChGs). These materials can be processed with broad compositional flexibility that allows tailoring of their transmission window, physical and optical properties, which allows them to be engineered for compatibility with other homogeneous amorphous or crystalline optical components. This paper reviews progress in forming ChG-based GRIN materials from diverse processing methodologies, including solution-derived ChG layers, poled ChGs with gradient compositional and surface reactivity behavior, nanocomposite bulk ChGs and glass ceramics, and meta-lens structures realized through multiphoton lithography (MPL).

Conventional photonic integration technologies are inevitably substrate-dependent, as different substrate platforms stipulate vastly different device fabrication methods and processing compatibility requirements. Here we capitalize on the unique monolithic integration capacity of composition-engineered non-silicate glass materials (amorphous chalcogenides and transition metal oxides) to enable multifunctional, multi-layer photonic integration on virtually any technically important substrate platforms. We show that high-index glass film deposition and device fabrication can be performed at low temperatures ( < 250 °C) without compromising their low loss characteristics, and is thus fully compatible with monolithic integration on a broad range of substrates including semiconductors, plastics, textiles, and metals. Application of the technology is highlighted through three examples: demonstration of high-performance mid-IR photonic sensors on fluoride crystals, direct fabrication of photonic structures on graphene, and 3-D photonic integration on flexible plastic substrates., National Science Foundation (U.S.) (Award 1200406)

Flexible integrated photonics is a new technology which only started to burgeon in the past few years, opening up emerging applications ranging from flexible optical interconnects to conformal sensors on biological tissues. One of the most important factors dictating the performance of these flexible devices is the material choice. Organic polymers are generally considered to be compatible with flexible substrates. However, the low refractive indices of polymers (compared to semiconductors) cannot provide the strong optical confinement necessary for compact photonic integration. Besides polymers, semiconductor NanoMembranes (NMs), thin slices of single crystal semiconductors with sub-micron thickness, are being actively pursued for photonic device integration on flexible substrates. Unlike their rigid bulk counterparts, NMs can be tightly bent without cracking, since surface strain induced by bending linearly scales with the membrane thickness. To make photonic devices, NMs structures are usually first patterned on a rigid substrate such as silicon. The fabricated structures are then picked up by a PDMS rubber stamp and transferred on to the final flexible substrate.This multi-step hybrid process limits processing yield and throughput. Therefore, we turned to amorphous glasses – the material of choice for optics given their exceptionally low optical attenuation. In flexible photonics, using these non-crystalline materials also enables a monolithic fabrication route as they can be directly deposited on to flexible substrates without resorting to epitaxial growth. Specifically, we focus on chalcogenide glass materials and amorphous TiO₂, as both can be deposited at relatively low temperature (250°C or less) compatible with flexible substrate integration [1-5].