Terahertz electro-absorption effect enabling femtosecond all-optical switching in semiconductor quantum dots

We demonstrate an instantaneous all-optical manipulation of optical absorption in InGaAs/GaAs quantum dots (QDs) via an electro-absorption effect induced by the electric field of an incident free-space terahertz signal. A terahertz signal with the full bandwidth of 3 THz was directly encoded onto an optical signal probing the absorption in QDs, resulting in the encoded temporal features as fast as 460 fs. The instantaneous nature of this effect enables femtosecond all-optical switching at very high repetition rates, suggesting applications in terahertz-range wireless communication systems with data rates of at least 0.5 Tbit/s. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3515909]