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Title: Electrical and Optical Gain Lever Effects in InGaAs Double Quantum Well Diode Lasers

Abstract

In multisection laser diodes, the amplitude or frequency modulation (AM or FM) efficiency can be improved using the gain lever effect. To study gain lever, InGaAs double quantum well (DQW) edge emitting lasers have been fabricated with integrated passive waveguides and dual sections providing a range of split ratios from 1:1 to 9:1. Both the electrical and the optical gain lever have been examined. An electrical gain lever with greater than 7 dB enhancement of AM efficiency was achieved within the range of appropriate DC biasing currents, but this gain dropped rapidly outside this range. We observed a 4 dB gain in the optical AM efficiency under non-ideal biasing conditions. This value agreed with the measured gain for the electrical AM efficiency under similar conditions. We also examined the gain lever effect under large signal modulation for digital logic switching applications. To get a useful gain lever for optical gain quenched logic, a long control section is needed to preserve the gain lever strength and a long interaction length between the input optical signal and the lasing field of the diode must be provided. The gain lever parameter space has been fully characterized and validated against numerical simulations of amore » semi-3D hybrid beam propagation method (BPM) model for the coupled electron-photon rate equation. We find that the optical gain lever can be treated using the electrical injection model, once the absorption in the sample is known.« less

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
940495
Report Number(s):
UCRL-JRNL-227058
Journal ID: ISSN 0018-9197; IEJQA7; TRN: US200824%%58
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Journal Article
Resource Relation:
Journal Name: IEEE Journal of Quantum Electronics, vol. 43, no. 10, October 1, 2007, pp. 860-868; Journal Volume: 43; Journal Issue: 10
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; 71 CLASSICAL AND QUANTUMM MECHANICS, GENERAL PHYSICS; ABSORPTION; AMPLITUDES; EFFICIENCY; FREQUENCY MODULATION; LASERS; MODULATION; QUANTUM WELLS; WAVEGUIDES

Citation Formats

Pocha, M D, Goddard, L L, Bond, T C, Nikolic, R J, Vernon, S P, Kallman, J S, and Behymer, E M. Electrical and Optical Gain Lever Effects in InGaAs Double Quantum Well Diode Lasers. United States: N. p., 2007. Web. doi:10.1109/JQE.2007.902796.
Pocha, M D, Goddard, L L, Bond, T C, Nikolic, R J, Vernon, S P, Kallman, J S, & Behymer, E M. Electrical and Optical Gain Lever Effects in InGaAs Double Quantum Well Diode Lasers. United States. doi:10.1109/JQE.2007.902796.
Pocha, M D, Goddard, L L, Bond, T C, Nikolic, R J, Vernon, S P, Kallman, J S, and Behymer, E M. Wed . "Electrical and Optical Gain Lever Effects in InGaAs Double Quantum Well Diode Lasers". United States. doi:10.1109/JQE.2007.902796. https://www.osti.gov/servlets/purl/940495.
@article{osti_940495,
title = {Electrical and Optical Gain Lever Effects in InGaAs Double Quantum Well Diode Lasers},
author = {Pocha, M D and Goddard, L L and Bond, T C and Nikolic, R J and Vernon, S P and Kallman, J S and Behymer, E M},
abstractNote = {In multisection laser diodes, the amplitude or frequency modulation (AM or FM) efficiency can be improved using the gain lever effect. To study gain lever, InGaAs double quantum well (DQW) edge emitting lasers have been fabricated with integrated passive waveguides and dual sections providing a range of split ratios from 1:1 to 9:1. Both the electrical and the optical gain lever have been examined. An electrical gain lever with greater than 7 dB enhancement of AM efficiency was achieved within the range of appropriate DC biasing currents, but this gain dropped rapidly outside this range. We observed a 4 dB gain in the optical AM efficiency under non-ideal biasing conditions. This value agreed with the measured gain for the electrical AM efficiency under similar conditions. We also examined the gain lever effect under large signal modulation for digital logic switching applications. To get a useful gain lever for optical gain quenched logic, a long control section is needed to preserve the gain lever strength and a long interaction length between the input optical signal and the lasing field of the diode must be provided. The gain lever parameter space has been fully characterized and validated against numerical simulations of a semi-3D hybrid beam propagation method (BPM) model for the coupled electron-photon rate equation. We find that the optical gain lever can be treated using the electrical injection model, once the absorption in the sample is known.},
doi = {10.1109/JQE.2007.902796},
journal = {IEEE Journal of Quantum Electronics, vol. 43, no. 10, October 1, 2007, pp. 860-868},
number = 10,
volume = 43,
place = {United States},
year = {Wed Jan 03 00:00:00 EST 2007},
month = {Wed Jan 03 00:00:00 EST 2007}
}
  • A new gain mechanism active in certain quantum well laser diode structuresis demonstrated and explained theoretically. It enhances the modulationamplitude produced by either optical or electrical modulation of quantum wellstructures. In the devices tested, power gains of 6 dB were measured from lowfrequency to frequencies of several gigahertz. Higher gains may be possible inoptimized structures.
  • Many-body effects on the optical gain in GaAsPN/GaP QW structures were investigated by using the multiband effective-mass theory and the non-Markovian gain model with many-body effects. The free-carrier model shows that the optical gain peak slightly increases with increasing N composition. In addition, the QW structure with a larger As composition shows a larger optical gain than that with a smaller As composition. On the other hand, in the case of the many-body model, the optical gain peak decreases with increasing N composition. Also, the QW structure with a smaller As composition is observed to have a larger optical gainmore » than that with a larger As composition. This can be explained by the fact that the QW structure with a smaller As or N composition shows a larger Coulomb enhancement effect than that with a larger As or N composition. This means that it is important to consider the many-body effect in obtaining guidelines for device design issues.« less
  • An anomalous dependence of the threshold current on the stripe width isobserved for gain-guided strained-layer InGaAs/GaAs quantum well lasers. Thethreshold current increases strongly as the stripe width is reduced fromrelatively large values. This is attributed to the huge lateral loss caused byan unusually large index antiguide which manifests itself in the far-fieldbehavior. This large loss also leads to a population of higher quantized energylevels in the InGaAs quantum well strongly reducing the lasing wavelength by asmuch as 61 nm.
  • The polarization dependent gain spectra of both tensile and compressive strain multiple quantum well (MQW) In{sub {ital x}}Ga{sub 1{minus}{ital x}}As-InP lasers in a relatively large strain regime were measured. MQW lasers having tensile strain with In concentration as low as 43% in the wells were found to lase in a pure transverse magnetic (TM) mode rather than a transverse electric (TE) mode, with a gain difference of 60--70 cm{sup {minus}1} at all the injection current investigated. The peak gain for the TE mode is shifted towards shorter wavelength from that of the TM mode indicating that the emission is principallymore » due to light hole-electron transition. The differential gain of the TM mode was also found to be about 1.5 times higher than the TE mode operation. Opposite effects were observed in the compressive strained MQW lasers.« less
  • Graded-index separate-confinement heterostructure InGaAs/AlGaAs single quantum well diode lasers emitting at 1.02 {mu}m have been fabricated from structures grown by organometallic vapor phase epitaxy. Under pulsed operation, threshold current densities as low as 65 A/cm{sup 2}, the lowest reported for InGaAs/AsGaAs lasers, have been obtained for a cavity length {ital L} of 1500 {mu}m. Differential quantum efficiencies as high as 90% have been obtained for {ital L}=300 {mu}m. Output powers as high as 1.6 W per facet and power conversion efficiencies as high as 47% have been obtained for continuous operation of uncoated lasers with {ital L}=1000 {mu}m.