Optical Waveguide of Buckled CdS Nanowires Modulated by Strain-Engineering

The optical waveguides under subwavelength scale are highly desirable for on-chip photonics to link various optical elements or to realize logical operations. In this work, the optical waveguiding along a single buckled CdS (cadmium sulfide) nanowire is comprehensively investigated at room temperature. By carefully scanning excitation along buckled nanowire with fixed PL detection at nanowire end, we present unique waveguide propagation loss strongly modulated by strain effect, which is distinct from the waveguide behavior of straight nanowires. When laser spot moves to buckling part, the light waveguide propagation loss is significantly reduced because band-to-band reabsorption effect during light propagation is greatly suppressed by tensile strain-induced bandgap shrinking. In addition, a dynamic manipulating waveguide propagation based on a controllable buckling of nanowires is also carried out; the solely strain-dependent waveguiding intensity loss and intensity modulation nearly 400% are clearly demonstrated. Our results indicate that strain-modulated semiconductor nanowires would pave new way to develop multifunctional optical elements and interconnects for integrated and flexible nanophotonic devices.