Experimental time-domain study of THz signals from impulse excitation of a horizontal surface dipole

Abstract

Using optoelectronic techniques with sub-ps resolution, we have characterized the electric-field time-domain response from an impulsively excited, micron-sized dipole antenna on a dielectric surface. When detected by an adjacent dipole antenna 400 μm distant, two primary signals are observed, a far-field pulse reflected from the back surface of the substrate and a surface-wave pulse. The surface-wave pulse appears as two distinct surface-propagating pulses despite originating from the dipole simultaneously.

Frozen wave generation of bandwidth-tunable two-cycle THz radiation

“…This time interval corresponds to the time it takes the THz radiation pattern to reflect off the back side of the GaAs substrate and be picked up again by the receiver, an effect similar to that observed by McGowan and Grischkowsky. 1 For a 600-m-thick substrate and a transmitter-receiver separation of 400 m, this propagation distance is in the near-field regime. The similarity between the transmitted signal of Fig.…”

“…With recent advances in the application of ultrashort laser pulses to optoelectronics, a new ultrahigh-frequency electromagnetic frontier ranging from 0.1 to 10 THz is being explored. Ultrashort THz pulses are currently being investigated for applications including inter-and intrachip communication, 1 spectroscopy and chemical identification, [2][3][4][5][6] miniature impulse radar, 7,8 and imaging. 9,10 A wide variety of techniques have been proposed and demonstrated in the generation, propagation, and detection of this freely propagating THz radiation.…”

Terahertz photonics: ultrafast physics and applications

“…Recent advances in ultrafast optically-activated PC switching has, for example, resulted in the generation of subpicosecond electrical pulses whose wide terahertz bandwidths are applied in integrated device characterization' and inter/intra-chip communication. 2 Similarly, recent advances in the development of terahertz sources and Hertzian dipole radiators have opened a new far-infrared frontier, bridging the electromagnetic gap between electronic and photonic devices. These free-space terahertz electromagnetic pulses are currently being applied in fields such as spectroscopy and chemical identification,' impulse ranging studies,4 and imaging.5 While a wide variety of techniques have been proposed and demonstrated in terahertz generation-including the implementation of non-linear interactions such as photomixing6 and optical rectification7-the most common approach employs the PC excitation of a Hertzian dipole source having an ultrafast time dependence.…”

Improved characteristics of a terahertz set-up built with an emitter and a detector made on proton-bombarded GaAs photoconductive materials

“…THz radiation has been generated by illuminating various emitters, including externally biased photoconductive (PC) antennas [3], surface built-in field biased semiconductors and nonlinear crystals with short optical pulses. Radiation-damaged silicon on sapphire (RD-SOS) [4][5][6] has been widely used as the substrate of PC antennas for generation and detection of THz radiation. In the last decade, low-temperature (LT) grown GaAs [7][8][9][10] has also been extensively used as a substrate.…”