Dynamical Characteristics of a Dual-Beam Optically Injected Semiconductor Laser

Dual-beam optically injected semiconductor lasers have been utilized in the field of microwave photonics for generations of microwave signals. To better understand the nonlinear behavior of a dual-beam optically injected semiconductor laser, we experimentally investigate the dynamics scenarios and their transition routes. By injecting a slave laser with beams from two master lasers, mappings of the dynamics scenarios including PP, PS, SP, SS, S' S', S' L, LS', and LL are plotted under different injection strengths and detuning frequencies. These scenarios are defined and differentiated by whether the dynamics and the characteristic frequencies originated from the single-beam injection scheme are being preserved (P), shifted (S), or suppressed (S') after both beams are simultaneously injected. The letter L is used if the slave laser is already injection-locked by one of the beams under the single-beam injection condition. The transition routes among these dynamics scenarios are shown to be clearly traceable by tracking and comparing the oscillation frequencies of the slave laser under the dual-beam and single-beam injections. Moreover, frequency-locking states are observed experimentally the first time in a dual-beam optically injected semiconductor laser, which occur when the frequency pushing effects from the two injected beams with opposite detunings balance each other off.