Three wave mixing in epsilon-near-zero plasmonic waveguides for signal regeneration

Vast improvements in communications technology are possible if the conversion of digital information from optical to electric and back can be removed. Plasmonic devices offer one solution due to optical computing's potential for increased bandwidth, which would enable increased throughput and enhanced security. Plasmonic devices have small footprints and interface with electronics easily, but these potential improvements are offset by the large device footprints of conventional signal regeneration schemes, since surface plasmon polaritons (SPPs) are incredibly lossy. As such, there is a need for novel regeneration schemes. The continuous, uniform, and unambiguous digital information encoding method is phase-shift-keying (PSK), so we chose to focus on developing a regeneration scheme compatible with PSK. Epsilon-near-zero (ENZ) materials have been shown to support SPP modes and have extremely high conversion rates for harmonic generation at their zero-permittivity wavelength, which makes them particularly desirable for developing signal regeneration devices. We have shown second-harmonic generation (SHG) in free space with simulations consisting of ENZ materials. When integrated into plasmonic waveguides, SHG can be used to conduct phase sensitive amplification (PSA), which allows us to combine phase-squeezing and amplification into a single stage instead of relying on conventional gain media for amplification. PSA can be utilized to design a proof-of-concept signal regeneration device with a smaller overall device footprint than previously demonstrated methods. The development of these methods will contribute towards minimizing device footprints of plasmonic components that require signal regeneration, improving their density and performance.