Direct Electrospray Printing of Gradient Refractive Index Chalcogenide Glass Films

Abstract

A spatially varying effective refractive index gradient using chalcogenide glass layers is printed on a silicon wafer using an optimized electrospray (ES) deposition process. Using solution-derived glass precursors, IR-transparent GeSbS and AsS glass films of programmed thickness are fabricated to yield a bilayer structure, resulting in an effective gradient refractive index (GRIN) film. Optical and compositional analysis tools confirm the optical and physical nature of the gradient in the resulting high-optical-quality films, demonstrating the power of direct printing of multimaterial structures compatible with planar photonic fabrication protocols. The potential application of such tailorable materials and structures as they relate to the enhancement of sensitivity in chalcogenide glass based planar chemical sensor device design is presented. This method, applicable to a broad cross section of glass compositions, shows promise in directly depositing GRIN films with tunable refractive index profiles for bulk and planar optical components and devices.

Advances in infrared gradient refractive index (GRIN) materials: a review

“…88 Figure 8(b) shows the gradient film deposition profile of a bilayer of GeSbS and AsS glasses (on Si), and the variation in effective index, n eff , calculated based on the layer thickness and parent glass refractive indices, as deposited on a SiN resonator array. 56 Such deposition requires an electrically conductive substrate (i.e., Si), but is amenable to plano and other shaped substrates. In addition, the magnitude of the resulting index gradient is only defined by the film thickness and the excursion (Δn) between the candidate glasses used.…”

Concentration dependence of As2S3 chalcogenide glass cluster size in amine solution

“…To attain z-averages from the model for comparison with experiments, the average cluster size was calculated from eqn (15) and used to generate a normal distribution of sizes with the standard deviation observed in cryo-TEM. The z-averages were then calculated using eqn (1).…”

“…12 The glasses dissolve in organic solvents and can then be doped, spin coated, or even inkjet printed with relative ease. [12][13][14][15] Previous research has shown numerous successful applications, including molded mid-IR waveguides, drop-cast photonic crystals, and optical bers with a nonlinearity-enhancing ChG coating. [16][17][18][19] The pioneering work on ChG solutions was done by Chern et al using As 2 S 3 in n-propylamine and n-butylamine as test systems.…”

Diffusion-based gradient index optics for infrared imaging

“…Electrospray deposition has been shown to produce large index gradients (Δn ¼ 0.4) in thin films and shows promise for imaging optics. 25 Ink-jet printing is used commercially at Voxtel Inc. for GRIN optics, primarily in the visible, but can be extended to the IR using suitable inks. 26 Thermal poling has been used to create GRIN profiles with small gradients (Δn ¼ 0.05) suitable for microlens arrays.…”