Tunable CW-THz system with a log-periodic photoconductive emitter

Comparison of photoexcited p-InAs THz radiation source with conventional thermal radiation sources

“…With this value of C, the maximum average absolute power achieved from the photoexcited InAs emitter ͑at 45°incidence and 300 mW of optical power͒ was found to be 98Ϯ 10 nW. Based on past experience in using a similar IRL bolometer side by side with a calibrated bolometer from QMC Instruments in U.K. for estimating terahertz power, 10 an independent estimate revealed an upper limit of 100 nW for the average absolute power, which is consistent with the above calculated value.…”

Thin film like terahertz bolometric detector on Bi2212 single crystal

“…YBCO high temperature superconducting thin film based microbolometer for THz radiation was demonstrated and response time of 300 ps was achieved (Hammar et al 2011). In addition to these, antenna structures were fabricated to provide higher sensitivity from the detectors (Mendis et al 2004;Hosseini et al 2011). In recent studies, bolometric detection from YBCO grain boundary Josephson junction has been realized where Bi2212 intrinsic Josephson junction was used as emitter ).…”

Progress in Compact Room Temperature THz Radiation Sources

“…There have been many improvements in the efficiency of these systems, as well as several completely different approaches to the naturally difficult problem of generating signals within the THz gap. Predominant devices and methods of generating THz radiation to date include: exploitation of nonlinear effects in EO crystals such as ZnTe [17,18] and periodically-poled LiNbO3 [19,20]; emission from gas lasers [21][22][23][24][25][26][27][28]; QCL's [29][30][31][32][33][34][35][36][37]; high frequency microwave electronics such as Gunn diodes and so-called uni-travelling-carrierphotodiodes [38][39][40][41][42]; and photomixing techniques based on heterodyning of multiple optical pump signals [43][44][45][46][47][48][49][50][51][52][53][54][55]. There are many different approaches with a widely varying degree of success, but this review will focus specifically on compact, room temperature sources which have seen some considerable improvement in recent years -particularly with some emphasis on the highly active and expanding field of THz heterodyne devices.…”

“…Early PC THz antennas were essentially micron-scale Hertzian dipole antennas, which were held at an appropriate electrical bias and were current-loaded when the active layer in the area between dipole gap was optically pumped/gated by the fs-pulse or CW beat signal. This gave limited performance in the CW regime and since then, enhanced THz output has been investigated with the use of broadband-emission, higher power antennas such as self-complimentary spiral [49,98] and circularly-toothed log-periodic designs [53,102,103], as well as traditional 'bow-tie' designs.…”