Analysis and characterization of the small-signal modulation of a vertical external cavity surface emitting laser

The small signal modulation of a vertical external cavity surface emitting laser (VECSEL) is examined. The modulation transfer function (MTF) of the cavity is measured for multiple photon lifetimes operating between Class A and Class B regimes, where the photon and carrier lifetimes are of the same order. Three coupled ordinary differential equations with similarities to an electrically-injected quantum-well laser with a separate confinement heterostructure are used to mathematically describe the time-dependant VECSEL response. We present a series of measurements that provide important laser parameters such as internal device losses and differential gain. The VECSEL operating in this regime is an overdamped oscillator and has free-running characteristics that are not unlike quantum-dot and quantum-cascade lasers.