Characteristics of large-aperture photoconductive terahertz antennas

Electrical and Radiation Characteristics of Semilarge Photoconductive Terahertz Emitters

“…The recombined beam, which carries the interference pattern, is incident on the emitter, causing variations in the intensity of the produced terahertz radiation detected by the Golay cell. We have investigated using this method to study the spectra of biased sources [19]. However, it was found that the results were radically different from those obtained by the terahertz interferometer and, furthermore, were inconsistent with the known performance of such emitters [16].…”

“…Indeed, if the bias voltage continues to rise, the current starts to grow nonlinearly and a thermal runaway sets in. It was found that the threshold voltage at which thermal runaway occurs depends inversely on the laser power and emitter aperture [19]. In LT GaAs, the photocurrent remains much lower, reducing the ohmic heating and increasing the threshold voltage for thermal runaway.…”

“…In initial experiments, reported in detail in [19], we attempted to measure the emitted terahertz spectra by using the autocorrelation technique employed elsewhere to observe spectra of unbiased plasmon emitters [18]. A typical trace, generated by the same source as in Fig.…”

Photoconductive emitters for pulsed terahertz generation

“…The distinction in photocurrent between the two materials is highlighted in figure 4. These results were confirmed by Stone et al [87] who suggested that while the thermal runaway of a device is dependent on optical power and active area, it is significantly higher for LT-GaAs-based-devices, owing to the reduced carrier mobility (120-200 cm 2 Vs −1 [84]) resulting in lower photocurrent and reduced ohmic heating [88]. Not fully researched, longer lifetimes >300 ps.…”