Surface polaritons have been shown to provide subwavelength confinement. Surface phonon polaritons (SPhPs), electromagnetic waves coupled to lattice vibrations in a polar dielectric, allow for highly confined propagating modes beyond the limit of diffraction within the mid to long infrared (IR). In recent years, it has been shown that hybrid plasmonic and phononic waveguides can support long-range hybrid modes that result from the coupling between SPhPs and a high index dielectric tracer. This work investigates the use of a hybrid phononic waveguide as a building block of a ring resonator that operates in the long wave infrared (LWIR) spectrum. Critical coupling condition and trade-off between ring diameter and output power are characterized. LWIR ring resonators hold promise for numerous applications including modulation, biosensing, photodetectors, and chemical sensing.
Surface phonon polaritons, SPhPs, result from the coupling or interaction of light with a phonon resonance. There has been extensive research into utilizing surface plasmon polaritons, SPPs, for subwavelength confinement of propagating waveguide modes for photonic integrated circuits. This work investigates the use of a multilayer system or insulatormetal-insulator (IMI) heterostructure as a SPhP-enhanced infrared waveguide where the metal response is due to phonons in a polar dielectric’s Reststrahlen band. In addition, an IMI heterostructure supports types of modes: an even mode and odd mode that have their own unique trade-offs. For the odd mode as the metal film thickness decreases the confinement of the SPhPs decreases, and thus resulting in an increase in the SPhPs propagation length. Conversely, the even mode shows the opposite behavior with decreasing metal film where the confinement increases as propagation length decreases. This endeavor investigates the trade-off between the even and odd IMI modes, and the characterization of propagation length and model confinement, as applied to a hybrid phononic waveguide.
Surface phonon polaritons (SPhPs), similar to it cousin phenomenon surface plasmon polaitons (SPPs), are quasi-neutral particles resulting from light-matter coupling that can provide high modal confinement and long propagation in the mid to long infrared (IR). Mach-Zehnder interferometer (MZI) is a combination of two connected optical directional couplers (ODC). With the use of SPhPs, sub-wavelength feature sizes and modal areas can be achieved and to this end a hybrid SPhP waveguide, where propagation length and modal area can be trade-off, will be employed in the design of an ODC and MZI. This endeavor analyzes and characteristics both an ODC and MZI using commercially available numerical simulation software employing finite element method (FEM). The ODC and MZI are design using a novel SPhP hybrid waveguide design where a 4H-SiC substrate provides the polariton mode. The output ports power and relative phase difference between ports are investigated. SPhP enhanced ODC and MZI has applications including, but not limited to, next-generation ultra-compact photonic integrated circuits and waveguide based IR sensing.
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