Collector current map of gain and stimulated recombination on the base quantum well transitions of a transistor laser

Data are presented showing significant structure in the collector $I-V$ characteristics of a transistor laser, a decrease (“compression”) in the common-emitter gain $(β≡ΔIC∕ΔIB)$⁠, that can be mapped in some detail and related to quantum well (QW) carrier recombination. The change in gain $(β)$ and laser wavelength corresponding to stimulated recombination (stimulated emission) on QW transitions, which is compared with operation in spontaneous recombination (cavity $Q$ spoiled), is used with conventional transistor charge analysis to reveal the dynamic properties of the transistor laser.