A terahertz radiation mixer for detecting an electromagnetic input signal having a radio frequency.
Terahertz applications remain relatively undeveloped because the terahertz region lies between the traditional microwave and optical regions of the electromagnetic spectrum, where electronic or photonic technologies have been developed for these purposes. Terahertz applications have been hampered due to the historically poor performance of terahertz components lying in the "technological gap" between these traditional electronic and photonic domains. There has been a need for a selective and tunable narrowband detector for terahertz spectrum analysis and imaging. Most solid state devices have had difficulty in this regard, because the electron energy relaxation times in such devices are typically much longer than the period of terahertz oscillations and terahertz energies are smaller than typical thermal energies. Therefore, the terahertz electromagnetic wave is oscillating too fast for free carriers to respond. A fast solid-state terahertz radiation mixer is still needed to enable coherent detection for terahertz applications requiring high resolution.
Researchers at the University of California, Santa Barbara have developed a terahertz radiation mixer for detecting an electromagnetic input signal having a radio frequency. The gate voltage can be tuned to modulate the electron density under the grating gate so that the local oscillator signal resonates with a spatial frequency of a standing plasmon resonance of the two-dimensional electron gas in the channel region. When operated on a plasmon resonance, the mixer provides a narrowband response with an intermediate frequency that can be up to 10 GHz or greater. Alternatively, the gate voltage can be greater than the pinch-off voltage of the field-effect transistor to provide a broadband pinch-off response having higher sensitivity.
This technology is available for licensing.
|United States Of America||Issued Patent||7,376,403||05/20/2008||2006-058|