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Proceedings Paper

Ultrafast all-optical modulation using intersubband transition in GaAs/AlGaAs quantum wells
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Paper Abstract

A picosecond modulation of interband (IB) resonant light (approximately 800 nm) by intersubband (ISB) resonant light (approximately 7 micrometers ) in n-doped GaAs/AlGaAs quantum wells is demonstrated. Two-color pump-probe measurements are carried out by using ultrashort (approximately 120 fs) ISB (pump) and IB (probe) light pulses at room temperature. Ultrafast modulation (FWHM approximately 1.3 ps) of the IB light is clearly observed with a low pump pulse energy of about 4 fJ/micrometers 2. The observed modulation depth is approximately 8.5% which corresponds to the absorption coefficient change of as large as approximately 1000 cm-1. The modulation depth decreases when the pump pulse wavelength is detuned from the ISB absorption peak. The modulation dependence on the ISB light pulse energy is also measured. The carrier relaxation mechanism in high and low excitation conditions is discussed by employing a numerical simulation of the relaxation process of electron-- longitudinal optical phonon systems. The results indicate that the utilization of the intersubband transition is promising for the ultrashort all-optical modulation and switching.

Paper Details

Date Published: 28 March 2000
PDF: 13 pages
Proc. SPIE 3940, Ultrafast Phenomena in Semiconductors IV, (28 March 2000); doi: 10.1117/12.381454
Show Author Affiliations
Takashi Asano, Kyoto Univ. (Japan)
Susumu Noda, Kyoto Univ. (Japan)


Published in SPIE Proceedings Vol. 3940:
Ultrafast Phenomena in Semiconductors IV
Kong-Thon F. Tsen; Jin-Joo Song, Editor(s)

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