The antiguiding parameter in mid-infrared optically pumped

摘要

We describe measurements of the antiguiding parameter, u0002, for several optically pumpednsemiconductor lasers. Three laser structures were investigated; two of the lasers utilize W-quantumnwells u0002QWsu0003 in which 14 InAs/ In0.4 GaSb/InAs QWs are imbedded in lattice-matched In0.25nGaAsSb layers. The emission wavelengths of the W lasers were u00043.5 and 4.5 u0003m, respectively.nThe other laser, a double heterostructure u0002DHu0003 design, contained a u00041.5 u0003m InAsSb active regionnembedded in u00042.5 u0003m thick AlAsSb clad regions. The emission wavelength of the DH was u0004nu00043.8 u0003m. We employed the Hakki–Paoli method u0005B. W. Hakki and T. L. Paoli, J. Appl. Phys., 44,n4113, u00021973u0003u0006 in conjunction with a Fourier transform infrared spectrometer to measurensubthreshold gain and index variations as a function of pump intensity. To reduce errors associatednwith incoherent background emission a full spectral curve fit was used to determine the differentialngain and index. The results reveal the antiguiding factor in the W lasers to be low with u0002u00041.0. Thenantiguiding factor for the DH was markedly larger with u0002=9.4u00051.3. We attribute the low u0002 for thenW lasers to the higher QW gain as well as to inhomogeneous broadening induced by the 14 QWs.nThe differing well widths and the independent optical pumping of the wells, leads to a net gainnspectrum that is symmetrical about the gain peak. This symmetry, in turn, leads to small differentialnindex shifts at the gain peak; the result of the small differential index and large differential gain isnlow antiguiding © 2010 American Institute of Physics. u0005doi:10.1063/1.3509798