Short description
(English)
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Quantum dot lasers and amplifiers operating at telecom wavelengths (1300-1550 nm) will be realised and characterised. Their performance will be assessed and optimised in terms of modal gain, noise, ultrafast gain dynamics and linewidth-enhancement factor. The effect of carrier confinement and energy quantisation on the laser characteristics will be investigated.
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Partners and International Organizations
(English)
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BE, BG,CH, CZ, DE, DK, ES, FI, FR, HU, IE, IL, IT, LT, MT, NL, PL, SE, TR, UK
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Abstract
(English)
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Based on the optimized epitaxial structures developed at the beginning of the project, we have grown, fabricated and characterized quantum dot (QD) lasers, superluminescent diodes (SLEDs) and semiconductor optical amplifiers (SOAs) with high gain and wide emission spectrum. SLEDs and lasers were fabricated and characterized also from epitaxial wafers grown by collaborating groups (Nanosemiconductors GmbH). A laser based on pseudomorphic InAs/GaAs QDs and emitting at 1430 nm was demonstrated, which represents a record wavelength in this material system. A SLED with a record spectral width >100 nm was also realized. Intraband carrier processes in lasers were investigated by measuring the lasing and the spontaneous emission spectra. The temperature dependence of the characteristics of lasers, SOAs and SLEDs was investigated by gain, spontaneous emission and carrier lifetime measurements. The phase dynamics in SOAs was also investigated in collaboration with Prof. Deveaud's group in EPFL, with Cardiff Univ. and with Alcatel research center in Marcoussis, France. Very large linewidth enhancement factors were measured, due to strong gain saturation in QDs. These results have been fully understood and reproduced on the basis of rate equation models including spatial dependence of carrier distribution and spectral distribution of QD energies. Moreover, the bandwidth limitations of QD lasers have been theoretically addressed, showing the role of intraband carrier relaxation.
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