A photoconductive antenna, consisting of a low temperature grown GaAs or InGaAs film covered with metallic contacts can be used as an optical excited broadband terahertz emitter for time domain measurements or as photomixer. Typically an alternating voltage is supplied to the electrical contacts of the transmitter antenna to allow a lock-in measurement. There are at least two important antenna parameters: the length l and the gap distance g. The length l determines the prefered emitted frequency at the resonance condition. The gap of the transmitter antenna between the metallic contacts can be larger than the laser spot diameter.
The PCA can be accomplished with a hyperhemispherical or an aspheric silicon substrate lens to increase the extraction efficiency for THz waves.

> PCA terahertz receiver
The PCA receiver has the same design as the transmitter. The optimal gap between the metallic contacts is about equal to the laser spot diameter. A current amplifier connected to the antenna contacts delivers a signal proportional to the terahertz electric field strength.

>  iPCA - large area interdigital photoconductive antenna
The iPCA is designated as high power THz transmitter, but can be used also as sensitive large area THz receiver. The interdigital antenna with a proprietary lens array converts high power laser pulses up to mean power levels of 5 W with a high power conversion efficiency of ~ 10^-4 into broadband THz pulses. More about iPCA ...

> Trademark iPCA™
iPCA is a trademark of BATOP GmbH registered under the number 30 2008 027 538  at the Deutsches Patent- und Markenamt in Germany.