Measurement of free-space terahertz pulses via long-lifetime photoconductors

Abstract

Antennas based on commercially available GaAs as a photoconductor with a subnanosecond photocarrier lifetime have been used to detect subpicosecond free-space electromagnetic radiation (THz pulses). At low optical gating intensities (≤1 mW/100 μm2), GaAs based antennas exhibit a higher responsivity and signal-to-noise ratio than typical antennas based on radiation-damaged silicon-on-sapphire.

Enhanced Terahertz Bandwidth and Power from GaAsBi‐based Sources

“…[ 51 ] Second, for THz emission, a shorter carrier lifetime is also necessary to create a cleaner high-frequency spectrum and to use the device in continuous-wave mode where two continuous-wave lasers with a frequency difference in the THz range are incident on the gap of the antenna. [ 51 ] Second, for THz emission, a shorter carrier lifetime is also necessary to create a cleaner high-frequency spectrum and to use the device in continuous-wave mode where two continuous-wave lasers with a frequency difference in the THz range are incident on the gap of the antenna.…”

Plasmonic photoconductive antennas for high-power terahertz generation and high-sensitivity terahertz detection

“…Photoconductive antennas are one of the most promising and commonly used means of terahertz generation and detection [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. This is mainly due to availability of high power, wavelength tunable, and compact optical sources with pulsed and continuous-wave operation required for broadband and narrowband terahertz generation/detection, respectively.…”

Terahertz photomixing in quantum well structures using resonant excitation of plasma oscillations

“…Alternative approaches to generate THz radiation are associated with optical techniques, that use a coherent output at the difference frequency ͑equal to the difference between the frequencies of radiation emitted by two lasers͒ or a response of photoconductive structures to femtosecond optical pulses. [1][2][3][4][5] Fast quantum well infrared photodetectors ͑QWIPs͒ utilizing intersubband transitions 6 can also be used for the generation of THz radiation by mixing infrared laser beams. Indeed, as shown theoretically, QWIPs can exhibit a marked response to infrared signals in the THz range of modulation frequencies if the electron transit time is short enough ͑as can be in single QWIPs 7,8 ͒ or if electrons reveal a pronounced velocity overshoot after their photoexcitation from QWs.…”