A spectral analysis of an integrated photomixer/antenna in a homodyne terahertz photomixing system

• Published in: Optics communications Vol. 286; pp. 363 - 367
• Main Authors: Ryu, Han-Cheol, Park, Seong-Ook, Kang, Kwang-Yong
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2013
• Subjects: Antennas; Dynamic range; Dynamical systems; Dynamics; Friis power transmission formula; Impedance; Impedance mismatch factor; Integrated photomixer/antenna; Power transmission; Propagation loss; Spectra; Terahertz photomixing; Wave generation; Friis power transmission formula; Impedance mismatch factor; Propagation loss; Terahertz photomixing; Integrated photomixer/antenna
• ISSN: 0030-4018; 1873-0310
• DOI: 10.1016/j.optcom.2012.09.021

An analysis has been carried out to estimate the spectral characteristics of an integrated photomixer/antenna in a homodyne photomixing system. The analysis adopts the impedance mismatch factor and Friis power transmission formula used in communication links based on the conventional analysis theory of a terahertz photomixer. The analysis and experimental results have proved that an impedance matching condition between the impedance of a photomixer and the input impedance of an antenna is directly related with photomixing terahertz wave generation. The Friis formula is introduced to calculate the propagation loss of the wave from a transmitter to a receiver in a homodyne photomixing system. A log-periodic antenna was used to ensure a high dynamic range in a broad frequency region. The dynamic range of the homodyne terahertz photomixing system was about 60dB near 100GHz and decreased with an increasing frequency from 10GHz to 1000GHz. The measured results agree well with the theoretically analyzed results and prove that the terahertz photomixing power is closely related to impedance mismatch factor and it could be estimated in the homodyne terahertz photomixing system without a terahertz power detector.