Abstract

The gain spectrum of a semiconductor laser diode (LD) or edge-emitting light emitting diode (LED) is directly related to the active region carrier density (n). The LD gain spectrum. may be obtained¹ from the modulation depth of below threshold Fabry-Perot fringes in the emission spectrum (Fig. 1), When high quality antireflection coatings ave applied to both LD facets, the device becomes an LED and a different method is needed for determining LED gain spectra. We make use of the fact that spontaneous emission is amplifed while propagating along the LD or LED index guide. In contrast, non-guided light, which is measured after passing through a window in the substrate, does not grow.

© 1993 Optical Society of America