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Spontaneous emission from InGaAs/GaAs quantum dots was investigated above the lasing threshold through windows structure on a laser diode. We found a clear evidence of slow carrier relaxation from the excited state to the ground state in a lasing condition.
Large cavity, very low threshold single layer quantum dot laser diodes with threshold current density of 10 A/cm2, output power > 2 W, and very-low internal loss of 0.25 cm-1 are achieved at CW room-temperature. Mode-locked operation of a large cavity laser diode with 40 mum stripe width is demonstrated at 3.75 GHz repetition rate.
Wavelength conversion using cross-gain modulation in quantum dot semiconductor optical amplifiers is investigated. Small signal measurements reveal that with increasing bias the cross-gain modulation converts from low efficiency, limited to 10 GHz bandwidth to a very efficient one with bandwidths well exceeding 40 GHz. Two different saturation mechanisms are responsible for this pronounced influence...
We numerically and experimentally demonstrate that high-speed small-signal cross- gain modulation of quantum-dot optical amplifiers can be improved by injecting carriers to excited states, which increases the amplifier's gain recovery time due to spectral hole burning.
Static cross gain saturation and dynamical small signal cross gain modulation are experimentally and theoretically investigated in order to judge the multi wavelength amplification capability of quantum dot semiconductor optical amplifiers (QD SOA). The measurements reveal the carriers in the excited states of the QDs to act as an effective reservoir, where QDs of different sizes participate in the...
This paper demonstrates that quantum dot optical amplifiers with significant excited state occupation exhibit symmetric saturation spectra due to very efficient carrier relaxation between excited and depleted ground states.
Novel cavity engineering techniques are used to realize low noise, and stabilized optical frequency combs from quantum well and quantum dot based modelocked semiconductor diode lasers. Applications in high speed signal processing, secure communications and arbitrary waveform generation are highlighted
We study the characteristics of ground-state and excite-state mode-locked pulse trains generated from an external cavity quantum dot mode-locked laser.
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