Absorption and single-pass gain measurements in optically pumped type-II midinfrared laser structures

A single-pass method was employed to measure the gain and absorption in optically pumped midinfrared type-II semiconductor lasers. The technique requires minimal sample processing and allows a single sample to be used for both absorption and gain measurements. The gain measurements confirm previous observations that the differential gain of these structures drops off rapidly with increasing temperature. A comparison of absorption in samples with differing waveguide designs was used to estimate the effective index step between the core and cladding.