Analytical Investigation on Period-one Oscillation Dynamics in Semiconductor Lasers

Description

Semiconductor lasers under nonlinear dynamics are unique photonic sources forgenerating a variety of microwave or millimeter-wave waveforms. Without any externalmodulations, the nonlinear dynamics can be invoked by simple perturbation schemessuch as the optical injection scheme. Over the past couple of years, the nonlineardynamical period-one (P1) oscillation state invoked by optical injection has attractednew attentions for tunable, single-tone photonic millimeter-wave generation. Theemission from a laser in P1 oscillation exhibits intensity oscillation at frequenciestunable from the microwave range to the millimeter-wave range. Different researchgroups, including our own, have experimentally demonstrated a number of applicationsof the P1 oscillation, which include photonic microwave signal amplification, radio-overfibercommunication, and millimeter-wave generation with phase noise reduction.Compared to the experimental works, theoretical analysis of the P1 oscillation remainsmuch less explored. In this proposal, we consider analytical investigations on the P1oscillation state. Modeling of the laser first follows the standard rate equations thatexpress the optical field by its envelope at the optical frequency. Confining the attentionto P1 oscillations allows one to simplify the envelope to individual oscillation frequencycomponents, which vary much slower than the P1 oscillation frequencies in themicrowave range. However, these very slowly varying frequency components contain themost important information for understanding the P1 oscillation state. Firstly, theproposed research will analytically investigate the modulation characteristics of the P1oscillation frequency components. Through generalizing a steady-state analysis of the P1frequency components, a time-varying analysis will be explored to reveal themechanisms of modulating P1 oscillations in radio-over-fiber and optical communicationapplications. Secondly, the proposed research will focus on arriving analytical results onthe noise contained in the P1 oscillation frequency components. Reduction of the phasenoise through schemes such as coherent feedback and incoherent feedback will beinvestigated analytically. Thirdly, the proposed research will consider analytically theenhancement of the harmonics of the P1 oscillation states. The beat signals of the higherharmonics are at multiples of the fundamental P1 oscillation frequency. Enhancing theseharmonics enables multiplication of the microwave or millimeter-wave frequenciesgenerated from P1 oscillations. Harmonics enhancement through optical feedbacks fromnonlinear optical media will be considered analytically. The proposed analyticalinvestigations on the P1 oscillation are expected to deepen the understanding of thenonlinear laser dynamics for photonic microwave applications.