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Title: Excitation Dependences of Gain and Carrier-Induced Refractive Index Change in Quantum-Dot Lasers.


Abstract not provided.

; ;
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
Report Number(s):
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Related Information: Proposed for publication in Applied Physics Letters.
Country of Publication:
United States

Citation Formats

Chow, Weng W., Lorke, M., and Jahnke, F.. Excitation Dependences of Gain and Carrier-Induced Refractive Index Change in Quantum-Dot Lasers.. United States: N. p., 2007. Web.
Chow, Weng W., Lorke, M., & Jahnke, F.. Excitation Dependences of Gain and Carrier-Induced Refractive Index Change in Quantum-Dot Lasers.. United States.
Chow, Weng W., Lorke, M., and Jahnke, F.. Sun . "Excitation Dependences of Gain and Carrier-Induced Refractive Index Change in Quantum-Dot Lasers.". United States. doi:.
title = {Excitation Dependences of Gain and Carrier-Induced Refractive Index Change in Quantum-Dot Lasers.},
author = {Chow, Weng W. and Lorke, M. and Jahnke, F.},
abstractNote = {Abstract not provided.},
doi = {},
journal = {Applied Physics Letters},
number = ,
volume = ,
place = {United States},
year = {Sun Apr 01 00:00:00 EDT 2007},
month = {Sun Apr 01 00:00:00 EDT 2007}
  • Influence of the free carrier component due to the plasma effect on carrier-induced refractive index change and its dependency on polarization for multiple-quantum-well (MQW) and bulk lasers are experimentally studied. The ratios of the component to the total index change, R[sub fc], are 0.6, 0.4, and 0.1 for the 1.3-[mu]m MQW, 1.3-[mu]m bulk, and 0.8-[mu]m MQW lasers, respectively. The TM/TE polarization ratios of the component, R[sub TM/TE], are 0.8 and 0.3 for 1.3-[mu]m MQW and 0.8-[mu]m MQW lasers. The relationship between the index change and the carrier overflow (to barrier and separate confinement heterostructure layers) for MQW lasers is alsomore » discussed. Large R[sub fc] and R[sub TM/TE] for the 1.3-[mu]m MQW laser result from the carrier overflow.« less
  • Measurements of the carrier induced refractive index change in AlGaAs quantum well lasers are presented which show that the guided mode in single quantum well lasers exhibits a small ( x 10/sup -22/ cm/sup 3/) carrier induced change in refractive index. This is more than an order of magnitude smaller than the corresponding value for conventional active layer lasers. The measured A// approx.-7 x 10/sup -21/ cm/sup 3/ in the active layers of AlGaAs multiquantum well structures. The measured index changes of the guided mode at threshold ( th/) are -5.6 x 10/sup -3/ and -7.6 x 10/sup -3/more » for the single quantum well and multiquantum well lasers, respectively. This should be compared with a value of approx.1.2 x 10/sup -2/ for conventional active layer lasers. These results suggest that single frequency sources fabricated using real index guided single quantum well active layers may have improved frequency stability under direct current modulation.« less
  • We investigated the loaded gain and the carrier-induced refractive-index change in quantum-well lasers. A quantum-well laser is found typically to have a higher gain and a smaller refractive-index change than a conventional diode laser. We also found that the gain and the refractive-index change for these two types of semiconductor lasers saturate similarly, with the refractive index being a much weaker function of laser intensity.
  • Measurements of the variation of differential gain, refractive index, and linewidth enhancement factor with carrier density in InGaAs-GaAs strained-layer quantum well lasers are presented for the first time. These results verify predictions of improvement over unstrained bulk or quantum well lasers, but only at certain carrier densities. Differential gain ({ital dg}/{ital dN}) is found to vary from 7.0{times}10{sup {minus}16} to 2.5{times}10{sup {minus}16} cm{sup 2} over the range of carrier densities studied, while the carrier dependence of the real part of the refractive index ({ital dn}/{ital dN}) ranges from a peak of {minus}2.8{times}10{sup {minus}20} down to {minus}7.0{times}10{sup {minus}21} cm{sup 3}. Frommore » these measurements the resulting linewidth enhancement factor ({alpha}) is found to vary from 5 to a minimum of 1.7. This information is critical to successfully exploiting the potential advantages of strained-layer lasers for such devices as high-frequency or narrow linewidth lasers.« less
  • The effects of valence-band mixing on the gain and on the refractive index change of the quantum-well laser and the effect of an applied electric field perpendicular to the quantum wells for gain switching are studied theoretically. Our calculations are based on the multiband effective-mass theory (kxp method) and the density-matrix formalism with the intraband relaxation taken into account. First, we calculate the nonparabolic valence-band structure by the finite difference method after making a unitary transformation of the Luttinger-Kohn Hamiltonian. The calculated gain for our model shows remarkable differences in both spectral shape and peak amplitude as compared with thosemore » for the conventional model of the parabolic valence band. The peak gain is reduced considerably and the gain spectrum is more symmetric in our model compared with that for the conventional model. The refractive index change shows a negative increment in the active region for both the TE and TM polarizations resulting in the antiguidance. However, the TM polarization shows more negative change which would result in the suppression of the TM modes as compared with the TE modes. As another example, the perpendicular electric field effects on the quantum-well laser with lateral current injection are also calculated. A red shift and a reduction of the gain spectrum are shown when an electric field is applied. This may have applications as a tunable and high-speed switching quantum-well laser.« less