TY - JOUR
T1 - Minimal group refractive index dispersion and gain evolution in ultra-broad-band quantum cascade lasers
AU - Gmachl, Claire
AU - Soibel, Alex
AU - Colombelli, Raffaele
AU - Sivco, Deborah L.
AU - Capasso, Federico
AU - Cho, Alfred Y.
N1 - Funding Information:
Manuscript received April 26, 2002; revised July 19, 2002. This work was supported in part by DARPA/US ARO under Contract DAAD19-00-C-0096. The authors are with Bell Laboratories, Lucent Technologies, Murray Hill, NJ 07974 USA (e-mail: [email protected]). Digital Object Identifier 10.1109/LPT.2002.804677
PY - 2002/12
Y1 - 2002/12
N2 - The group refractive index dispersion in ultra-broad-band quantum cascade (QC) lasers has been determined using Fabry-Pérot spectra obtained by operating the lasers in continuous wave mode below threshold. In the wavelength range of 5-8 μm, the global change of the group refractive index is as small as +8.2 × 10-3 μm-1 Using the method of Hakki and Paoli, the subthreshold gain of the lasers has furthermore been measured as a function of wavelength and current. At the wavelength of best performance, 7.4 μm, a modal gain coefficient of 16 cm·kA-1 at threshold and a waveguide loss of 18 cm-1 have been estimated. The gain evolution confirms an earlier assumption that cross-absorption restricted laser action to above 6 μm wavelength.
AB - The group refractive index dispersion in ultra-broad-band quantum cascade (QC) lasers has been determined using Fabry-Pérot spectra obtained by operating the lasers in continuous wave mode below threshold. In the wavelength range of 5-8 μm, the global change of the group refractive index is as small as +8.2 × 10-3 μm-1 Using the method of Hakki and Paoli, the subthreshold gain of the lasers has furthermore been measured as a function of wavelength and current. At the wavelength of best performance, 7.4 μm, a modal gain coefficient of 16 cm·kA-1 at threshold and a waveguide loss of 18 cm-1 have been estimated. The gain evolution confirms an earlier assumption that cross-absorption restricted laser action to above 6 μm wavelength.
KW - Mid-infrared
KW - Quantum cascade (QC) laser
KW - Semiconductor lasers
KW - Semiconductor waveguides
KW - Waveguide measurements
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U2 - 10.1109/LPT.2002.804677
DO - 10.1109/LPT.2002.804677
M3 - Article
AN - SCOPUS:0036895557
SN - 1041-1135
VL - 14
SP - 1671
EP - 1673
JO - IEEE Photonics Technology Letters
JF - IEEE Photonics Technology Letters
IS - 12
ER -