Browsing by Author "Wu, Y. C."

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    Carrier capture delay and modulation bandwidth in an edge-emitting quantum dot laser
    Asryan, Levon V.; Wu, Y. C.; Suris, R. A. (AIP Publishing, 2011-03-01)
    We show that the carrier capture from the optical confinement layer into quantum dots (QDs) can strongly limit the modulation bandwidth omega(-3) dB of a QD laser. As a function of the cross-section sigma(n) of carrier capture into a QD, omega(-3) dB asymptotically approaches its highest value when sigma(n) -> infinity the case of instantaneous capture). With reducing sigma(n), omega(-3) dB decreases and becomes zero at a certain nonvanishing sigma(n)(min). The use of multiple-layers with QDs significantly improves the laser modulation response-omega(-3) dB is considerably higher in a multilayer structure as compared to a single-layer structure at the same dc current. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3571295]
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    Effect of excited states on the ground-state modulation bandwidth in quantum dot lasers
    Wu, Y. C.; Suris, R. A.; Asryan, Levon V. (AIP Publishing, 2013-05-01)
    We consider direct and indirect (excited-state-mediated) capture of carriers from the waveguide region into the lasing ground state in quantum dots (QDs) and calculate the modulation response of a QD laser. We show that, when only indirect capture is involved, the excited-to-ground-state relaxation delay strongly limits the ground-state modulation bandwidth of the laser-at the longest tolerable relaxation time, the bandwidth becomes zero. When direct capture is also involved, the effect of excited-to-ground-state relaxation is less significant and the modulation bandwidth is considerably higher. (C) 2013 AIP Publishing LLC.
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    Effect of internal optical loss on the modulation bandwidth of a quantum dot laser
    Wu, Y. C.; Suris, R. A.; Asryan, Levon V. (AIP Publishing, 2012-03-01)
    We show that the internal optical loss, which increases with free-carrier density in the waveguide region, considerably reduces the modulation bandwidth omega(-3 dB) of a quantum dot laser. At a certain optimum value j(0)(opt) of the dc component of the injection current density, the maximum bandwidth omega(max)(-3dB) is attained and the modulation response function becomes as flat as possible. With internal loss cross-section sigma(int) increasing and approaching its maximum tolerable value, omega(max)(-3dB) decreases and becomes zero. As with j(0)(opt), there also exists the optimum cavity length, at which omega(-3 dB) is highest; the larger is sigma(int), the longer is the optimum cavity. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3697683]