A dry-etched pedestal chalcogenide waveguide platform, designed for use in long-wave IR spectrometer applications, is demonstrated, fabricated and optically characterized. The optical layers were deposited on pre-patterned dry-etched silicon pedestals. An exceptionally low waveguide propagation loss was measured, at around 0.1 dB/cm at λ = 10 μm. The modal thermo-optic coefficient of the waveguide was experimentally estimated to be approximately 1.1 × 10⁻⁴ C⁻¹ at λ = 1.63 μm, which is comparable to that of Si and GaAs. Waveguide spiral interferometers were fabricated, proving the potential for realization of more complex, chalcogenide-based, integrated photonic circuits. The combination of low propagation losses and a strong thermo-optic coefficient makes this platform an ideal candidate for utilization in on-chip tunable spectrometers in the long-wave IR wavelength band.

This study investigates the broadband plasmonic resonance properties of gold-based surface-enhanced Raman spectroscopy (SERS) substrates with stochastically disordered nanostructures. We fabricated a nanotextured template topped with sputtered gold. Field emission scanning electron microscopy (FE-SEM) analysis showed random gold nanoclusters with different densities, sizes, and orientations. Simulation results indicated a large number of electromagnetic (EM) modes, including first- and second-generation hotspots as well as touching point geometries that provide a large enhancement factor. With any given excitation wavelength, such disordered SERS structures can provide some mode configurations that resonance, resulting in broadband response. SERS simulations showed considerable electric field intensification across a wide range of wavelengths (600–1600 nm) and provided a relatively uniform SERS response with an areal-averaged enhancement factor ~10 ⁵ across a broad visible to near-infrared range.