An optically-driven THz-modulator
| Autor: | J. Feldmann, N. E. Hecker, Phil Dawson, Imke. H. Libon, Martin Koch, M. Hempel |
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| Rok vydání: | 2003 |
| Předmět: |
Physics
Terahertz radiation business.industry Carrier generation and recombination Optical polarization Optical power Electron Condensed Matter::Mesoscopic Systems and Quantum Hall Effect Gallium arsenide Optical pumping chemistry.chemical_compound chemistry Excited state Optoelectronics Atomic physics business |
| Zdroj: | Technical Digest. Summaries of papers presented at the Conference on Lasers and Electro-Optics. Postconference Edition. CLEO '99. Conference on Lasers and Electro-Optics (IEEE Cat. No.99CH37013). |
| DOI: | 10.1109/cleo.1999.834321 |
| Popis: | Summary form only given. Mixed type-I/type-II GaAs/AlAs double quantum wells (QW) offer a means of generating electron-hole pairs with a lifetime which can exceed 400 /spl mu/s. For the sample chosen for the measurements discussed here, electrons excited in the /spl Gamma/-valley of the narrow well are transferred to the X-valley in the barrier material and subsequently to the /spl Gamma/-valley of the wider well. The recombination rate of the spatially separated electron-hole pairs is dominated by the tunneling rate of holes from the narrow well into the wider well. This leads to an intrinsically long life-time of the spatially separated electron-hole pairs which enables large carrier densities (7/spl times/10/sup 11/ cm/sup -2/) to be excited with low optical power densities (0.07 W/cm/sup 2/). We have exploited these high carrier lifetimes and densities to build an optically controlled THz-modulator with large contrast ratios for extremely low optical power. |
| Databáze: | OpenAIRE |
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