Curvature-Driven Modulation of Waveguide Lasing in Buckled CdS Nanowires for Mechanically Reconfigurable On-Chip Light Sources

Abstract

Dynamic control of the lasing behavior in semiconductor nanowires is crucial for the development of mechanically reconfigurable on-chip light sources for flexible photonic integrated circuits and wearable optical sensors. In this work, we report on mechanically tunable waveguide lasing in strain-engineered buckled CdS nanowires. Periodic in-plane buckling generates tensile strain along curved segments, resulting in bandgap reduction, as confirmed by spatially resolved photoluminescence redshifts. Power-dependent PL measurements reveal the emergence of discrete, sharp emission peaks above a threshold, indicating the onset of multimode lasing. As the applied strain increases from 0.9% to 11.6%, the dominant lasing mode exhibits a redshift from 519.1 nm to 520.1 nm, accompanied by an increase in the lasing threshold from ∼35 to 44 μJ cm−2. The relatively limited tuning range compared to the PL shift is attributed to the cavity-governed nature of lasing and the weak strain-induced variation in the refractive index. Finite-difference time-domain (FDTD) simulations further reveal that increased curvature leads to enhanced radiation loss and reduced optical confinement, consistent with the observed threshold increase and Q-factor degradation. These findings demonstrate that mechanical strain enables simultaneous modulation of the electronic band structure and photonic cavity behavior, establishing buckled CdS nanowires as promising platforms for mechanically reconfigurable on-chip nanolasers for flexible photonic and wearable sensing systems.