On the linewidth enhancement factor in semiconductor lasers

Olofsson, L.; Brown, Thomas G.

doi:10.1063/1.103783

Cited by 17 publications

(1 citation statement)

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“…A preliminary report on our modeling studies has been published. 4 The LWEF is one of the most important parameters of the semiconductor lasers for many practical applications 5,6 . It describes the carrier induced coupling of the gain change to the refractive index change in the active region of the semiconductor laser.…”

Section: Introductionmentioning

confidence: 99%

Linewidth enhancement factor and modulation bandwidth of lattice-matched 1.5 micron InGaAsN/GaAs quantum well lasers

et al. 2004

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The linewidth enhancement factors of lattice-matched 1.5 µm wavelength InGaNAs/GaAs and InGaAs/InP singlequantum-well structures have been calculated using microscopic theory including many-body effects and a 10x10 effective-mass Hamiltonian. For applications which require high gain and carrier densities, InGaNAs/GaAs quantum wells have a much lower linewidth enhancement factor over a temperature range 300-400 K than InGaAs. The linewidth enhancement factor of InGaNAs is almost independent of both carrier density and temperature compared with InGaAs. The small-signal modulation characteristics of these 1.5µm lattice-matched structures and their temperature dependence have also been calculated. It is found that the maximum bandwidth of the InGaNAs/GaAs quantum well lasers is about 2.3 times larger than that of the InGaAs/InP quantum well lasers due to the high differential gain. The slope efficiency for the 3dB bandwidth as a function of optical density is twice as large for InGaNAs/GaAs as for InGaAs/InP quantum well lasers. Key-words:InGaAsN materials, Semiconductor quantum wells, linewidth enhancement factor, small signal modulation, bandwidth. INTRODUCTIONInGaAsN/GaAs quantum wells (QWs) have recently been shown to be very promising materials systems as active media for long wavelength lasers at 1.3 µm and possibly 1.5 µm in optical communications systems 1 . The large conduction band offset in the InGaAsN system results in a much greater electron confinement compared with the InGaAsP system and should result in much improved high temperature performance in optimized devices 2,3 . In addition, the large refractive index difference in this AlAs-GaAs based system makes it possible to fabricate monolithic Bragg reflectors with a small number of mirror pairs. For use as practical laser systems, a number of key performance parameters need to be investigated for the InGaAsN system and compared with the standard InGaAsP system in order to be able to best choose the system for its particular application. We have carried out a modeling study of the linewidth enhancement factor (LWEF) and the small signal modulation characteristics as a function of carrier density and temperature. The results show that InGaAsN quantum wells have much superior properties over the InGaAs system which is presently used in communications systems lasers. There remains a problem with the growth of InGaAsN materials and as yet, lattice matched materials at 1.5 microns have not been grown. A preliminary report on our modeling studies has been published. 4 The LWEF is one of the most important parameters of the semiconductor lasers for many practical applications 5,6 . It describes the carrier induced coupling of the gain change to the refractive index change in the active region of the semiconductor laser. The laser linewidth, modulation-induced wavelength chirp, gain guiding, and sensitivity to feedback are dependent on the LWEF. To explore the optimization conditions, it is very important to investigate the dependencies of the LWEF o...

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Section: Introductionmentioning

confidence: 99%