The Terahertz laboratories are actively involved in creating new emitters and detection techniques at terahertz frequencies.

Optical Gating of Graphene

We demonstrate experimentally nonvolatile, all-optical control of graphene’s charge transport properties by virtue of an Fe:LiNbO3 photoconductive substrate. The substrate can register and sustain photoinduced charge distributions which modify locally the electrostatic environment of the graphene monolayer and allow spatial control of graphene resistivity.

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Novel emitters

Research involving the creation of new THz antennas, particularly antennas that do not require electrical bias signal. Currently, the group is focussing on antennas that utilise the lateral photo-Dember effect, where the diffusion of photo-excited carriers is responsible for the emitted THz waves.

Novel THz emitters

The photo-Dember (PD) effect is a THz emission mechanism based on ultrafast carrier transport. THz radiation is produced by illumination of a semiconductor surface by an ultrafast near infrared laser with energy above the bandgap (usually Ti:S). The strong absorption of light near the surface creates a large carrier gradient of electrons and holes, which …

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Semiconductor Disk Lasers or VECSELs

We researche a type of optically pumped semiconductor laser that is called the Vertical External Cavity Surface Emitting Laser (VECSEL).

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Parameter Extraction Algorithm

Transfer Function based refractive index extraction algorithm for THz-TDS   The algorithm uses a transfer function to extract a refractive index from a slab material. It works for THz time domain spectroscopy measurements that have been taken in a transmission geometry. For inputs the algorithm requires; a time domain scan of a sample, a time …

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THz basics

The Terahertz part of the electromagnetic spectrum spans between the optics and electronics regions (infrared and microwave wavelegnths); 1 THz has a wavelength of 300 μm, energy of 4 meV, and a wavenumber of 33 cm-1. Phenomena within the Terahertz energy range are based mostly on molecular rotation (H2O, O2, CO etc.) and on interactions …

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