  We describe the electronic control of extraordinary terahertz transmission
through subwavelength metal hole arrays fabricated on doped semiconductor
substrates. The hybrid metal-semiconductor forms a Schottky diode structure,
where the active depletion region modifies the substrate conductivity in
real-time by applying an external voltage bias. This enables effective control
of the resonance enhanced terahertz transmission. Our proof of principle device
achieves an intensity modulation depth of 52% by changing the voltage bias
between 0 and 16 volts. Further optimization may result in improvement of
device performance and practical applications. This approach can be also
translated to the other optical frequency ranges.
