Beyond current modulation: pump ellipticity-driven GHz polarized pulse generation in a solitary dual state QD spin-VCSEL

Abstract

Spin-polarized vertical-cavity surface-emitting lasers (spin-VCSELs) have emerged as promising candidates for next-generation high-speed photonic systems due to their unique polarization dynamics. Here, we numerically simulate the generation of high-repetition-rate polarized optical pulses in a solitary dual-state quantum-dot (QD) spin-VCSEL by applying return to zero pulse modulation of the pump ellipticity (P). Unlike conventional modulation schemes relying on current variation or optical injection, our approach exploits the inherent dependence of the lasing threshold on P. By maintaining a steady injection current and dynamically switching P between different ellipticities, we induce a controlled transition between the non-lasing and lasing states, effectively generating optical pulses with controlled polarization. This mechanism enables pulse repetition rates reaching up to 15 GHz, paving the way for novel ultrafast modulation schemes in spintronic photonic devices. Our findings open new perspectives for energy-efficient, semiconductor lasers-based, high-speed optical communication and neuromorphic photonic processing by taking advantage of spin-dependent nonlinear dynamics in VCSELs.