Angle- and polarization-independent mid-infrared narrowband optical filters using dense arrays of resonant cavities.

We report design and experimental verification of narrowband mid-infrared optical filters with transmission characteristics that are practically constant over a wide range of incident angles. The filter employs a dense array of dielectric resonant cavities in a metal film, where the transmission of each cavity depends upon localized rather than travelling fields, making the filter fundamentally angle-independent. We show experimentally a transmission around 90% from normal incidence up to 60°.

Room-temperature-deposited dielectrics and superconductors for integrated photonics.

We present an approach to fabrication and packaging of integrated photonic devices that utilizes waveguide and detector layers deposited at near-ambient temperature. All lithography is performed with a 365 nm i-line stepper, facilitating low cost and high scalability. We have shown low-loss SiN waveguides, high-Q ring resonators, critically coupled ring resonators, 50/50 beam splitters, Mach-Zehnder interferometers (MZIs) and a process-agnostic fiber packaging scheme.

Far-infrared absorber based on standing-wave resonances in metal-dielectric-metal cavity.

Thin-film resonant absorbers for the far-IR spectral range were fabricated, characterized, and modeled. The 3-μm-thick structure comprises a periodic surface array of metal squares, a dielectric spacer and a metallic ground plane. Up to 95% absorption for the fundamental band at ~53.

Platinum germanides for mid- and long-wave infrared plasmonics.

Platinum germanides (PtGe) were investigated for infrared plasmonic applications. Layers of Pt and Ge were deposited and annealed. X-ray diffraction identified PtGe(2) and Pt(2)Ge(3) phases, and x-ray photo-electron spectroscopy determined vertical atomic composition profiles for the films.

Long-wave infrared tunable thin-film perfect absorber utilizing highly doped silicon-on-sapphire.

We show that nearly perfect absorption can be achieved in a simple structure with highly doped silicon on a sapphire (SOS) substrate. An SOS structure with the n-Si film being 600 nm thick and having doping concentration of 2e19 cm(-3) has an absorption peak of 96% in the film at a wavelength of 12.1 μm.

Mid- to long-wavelength infrared plasmonic-photonics using heavily doped n-Ge/Ge and n-GeSn/GeSn heterostructures.

Heavily doped n-type Ge and GeSn are investigated as plasmonic conductors for integration with undoped dielectrics of Si, SiGe, Ge, and GeSn in order to create a foundry-based group IV plasmonics technology. N-type Ge1-xSnx with compositions of 0 ≤ x ≤ 0.115 are investigated utilizing effective-mass theory and Drude considerations.

Infrared surface polaritons on antimony.

The semimetal antimony, with a plasma frequency ~80 times less than that of gold, is potentially useful as a host for infrared surface polaritons (SPs). Relevant IR SP properties, including the frequency-dependent propagation length and penetration depths for fields into the media on either side of the interface, were determined from optical constants measured on optically-thick thermally-evaporated Sb films over the wavelength range 1 to 40 μm. Plasma and carrier relaxation frequencies were determined from Drude-model fits to these data.

Long-wave infrared surface plasmon grating coupler.

We present a simplified analytic formula that may be used to design gratings intended to couple long-wave infrared radiation to surface plasmons. It is based on the theory of Hessel and Oliner (1965). The recipe is semiempirical, in that it requires knowledge of a surface-impedance modulation amplitude, which is found here as a function of the grating groove depth and the wavelength for silver lamellar gratings at CO(2) laser wavelengths.