Enhanced second-harmonic generation from metal-integrated semiconductor nanowires via highly confined whispering gallery modes

Abstract

Coherent and tunable nanoscale light sources utilizing optical nonlinearities are required for applications ranging from imaging and bio-sensing to on-chip all-optical signal processing. However, owing to their small sizes, the efficiency of nanostructures even with high nonlinear coefficients is poor, therefore requiring very high excitation energies. Although surface-plasmon resonances of metal nanostructures can enhance surface nonlinear processes such as second-harmonic generation, they still suffer from low conversion efficiencies owing to their intrinsically low nonlinear coefficients. Here we show highly enhanced and directional second-harmonic generation from individual CdS nanowires integrated with silver nanocavities (41,000 times higher external efficiency compared with bare CdS), in which the lowest-order whispering gallery mode is engineered to concentrate light in the nonlinear material while minimizing Ohmic losses. The directional nonlinear signal is redirected into another waveguide, which is then utilized to configure an optical router that can potentially serve as a tunable coherent light source to enable on-chip signal processing for integrated nanophotonic systems.

Investigation of non-linear optical properties of CdS/PS polymer nanocomposite synthesized by chemical route

“…CdS also exhibits large second order non-linear coefficient [15]. Ren et al [16] had studied the second order non-linearity of CdS nanowires incorporated with silver nanocavities and utilized it in optical router for nanophotonic systems. Liu et al [17] had studied the effect of thermal/electrical poling on second-harmonic generation (SHG) in CdS-doped glasses.…”

Room-temperature polarized spin-photon interface based on a semiconductor nanodisk-in-nanopillar structure driven by few defects

“…They exhibit interesting optical properties superior to their flat-surface counterparts of semiconductor materials in the 3D and 2D geometry, such as enhanced light absorption and emission, waveguiding of light and light confinement thanks to a high refractive index contrast with respect to the surroundings (e.g., air), a large surface-to-volume ratio, etc. In the past decade, they have been extensively investigated as building blocks in nano-photonics, nano-photovoltaics, and nano-sensing 1,2 , including light emitting diodes (LEDs) 3–5 , photovoltaic (PV) cells 6–9 , photo-detectors 10–13 , nanolasers 14,15 , nonlinear optics 16–19 , and bio-sensors 20–22 , all on the nanoscale. NPs/NWs also function as natural axial Fabry-Perot (FP) and radial whispering-gallery (WG) mode cavities with tailorable optical modes 23,24 .…”

Nanotwin Detection and Domain Polarity Determination via Optical Second Harmonic Generation Polarimetry

“…polycrystalline monolayer MoS 2 28 . At the nanoscale (<300 nm), SHG has also been studied 29 and demonstrated to probe growth orientation 30,31 and crystal structure 30,32 of nanowires (NWs).…”

“…In this work, we study and analyze multiple nanotwins in ZB CdTe NWs and nanobelts (NBs) via the SHG polarimetry technique29,32 , and quantitatively resolve the nature of the twin boundaries (upright versus inverted), a task which is otherwise challenging to accomplish. Moreover, due to distinct SHG polarimetric signals observed in periodically twinned CdTe NWs, it was ascribed to inverted twin boundaries rather than energetically favorable upright twin boundaries, showing clear evidence of inverted twin boundaries that have been rarely detected in NWs 21 .To understand the nature of upright and inverted twin boundaries, we need to consider four different domains of ZB CdTe and their interfaces with each other.…”