Ultrabroadband electrical terahertz modulator based on metal microslits and n-doped GaAs formed Schottky diode

An ultrabroadband electrical terahertz modulator exploited periodic metal microslits on n-GaAs layer forming a Schottky diode structure was proposed and demonstrated. The carrier concentration between the gap of microslits in the n-GaAs layer was modified by an external reverse bias voltage, which enabled effective modulation of the transmitted THz signal in a broad bandwidth. Our proof of principle device achieved an intensity modulation depth of ~45% by changing bias voltage between 0 and -5 volts. Further optimization, such as the free carrier density and parameters of the microslits, may further improve the device performance.