A major bottleneck with high-frequency wireless communications is the conversion from radio frequencies to optical signals and vice versa. This is performed by an electro-optic modulator (EOM), which generally are limited to GHz-level signals. To reach THz speeds, a new approach was needed, which researchers at ETH Zurich in Switzerland claim to have found in the form of a plasmonic phase modulator.
Although sounding like something from a Star Trek episode, plasmonics is a very real field, which involves the interaction between optical frequencies along metal-dielectric interfaces. The original 2015 paper by [Yannick Salamin] et al. as published in Nano Letters provides the foundations of the achievement, with the recent paper in Optica by [Yannik Horst] et al. covering the THz plasmonic EOM demonstration.
The demonstrated prototype can achieve 1.14 THz, though signal degradation begins to occur around 1 THz. This is achieved by using plasmons (quanta of electron oscillators) generated on the gold surface, who affect the optical beam as it passes small slots in the gold surface that contain a nonlinear organic electro optic material that ‘writes’ the original wireless signal onto the optical beam.
