Anomalous longitudinal mode hops in GaAs/AlGaAs distributed Bragg reflector lasers

We investigate normal and anomalous longitudinal mode hops in GaAs/AlGaAs-based distributed Bragg reflector (DBR) lasers; anomalous mode hops are defined as those which move toward shorter wavelengths with increasing temperature, which is unexpected. The two-section DBR lasers discussed in this letter, consisting of a gain section and an unpumped Bragg reflector, typically exhibit one mode hop in a 10 K temperature range. Although the longer wavelength modes are expected to start lasing when raising device temperature, occasional mode hops to a shorter wavelength are seen. We derive a model for temperature-dependent wavelength tuning, with which the overheating of the gain section is described empirically. This model allows an accurate numerical simulation of both kinds of temperature-induced longitudinal mode hops.