Terahertz Electro-Optics

Terahertz (THz) electro-optics (EO) is the modulation of a material's optical properties by application of an electric field oscillating at THz frequencies (>1000 GHz). I study THz EO in GaAs quantum wells.

Essentially, a THz EO experiment consists of shining a weak near-infrared (NIR, wavelength around 800 nm) laser beam onto a sample simultaneously with an intense THz laser beam from a Free Electron Laser. Then I collect the NIR light that comes out, and see how its absorption and emission spectrum has been changed by presence of the THz beam.

Some things I observe are:

• absorption lines that shift due to coherent mixing of states with the THz field.
• photoluminescence quenched or enhanced by carrier heating and resonant absorption of THz by excitons.
• nonlinear frequency mixing of the THz and NIR light

There are a wealth of excitations within conduction and valence bands that resonate at THz frequencies, including: internal exciton transitions, excitonic intersubband transitions, cyclotron resonance, intersubband plasmons, etc. These excitations can be spectroscopically studied by use of THz EO, by measuring the strength of a THz EO effect vs some tuning parameter such as THz frequency or magnetic field. Conversly, they can be exploited to resonantly enhance THz EO effects for practical use.

Terahertz Electro-optics Publications.

Visit our nonlinear THz dynamics page for more quantum well physics.

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