We developed a novel lab-on-a-chip device with the capability of rapidly pre-concentrating for Raman detection that use gold bead as the solid carrier of biomolecules. The device combines an array of patterned plasmonic surface (i.e. gold nano-ellipses), as the bead manipulation element. The purpose of gold bead manipulation is to provide sample pre-concentration in close proximity of the Raman detecting region. In the presence of an external uniform electric field, the gold ellipses create local electric field gradients (which is usually called hot spots) that capture the gold beads. The location of hot spots within a plasmonic nanostructure is polarization dependent, and inhomogeneous electric field between two adjacent nano-ellipses perpendicular to each other leads to highly unbalanced trap potential that give the chance of transferring trapped particles in a given direction through rotating the polarization. Nano-optical conveyor belts with staircase pattern of nano-ellipses were arranged with their terminus collected at detection area to gather biomolecules. With the capacity to transfer biomolecules precisely, our design offers an attractive scheme for rapid, high throughput and highly sensitive sensing of low abundance analytes.
For optical manipulation, a nano-optical conveyor belt consisting of an array of gold plasmonic non-concentric nano-rings (PNNRs) is demonstrated for the realization of trapping and unidirectional transportation of nanoparticles by polarization rotation of excitation beam. These hot spots of an asymmetric plasmonic nanostructure are polarization dependent, therefore, one can use the incident polarization state to manipulate the trapped targets. Trapped particles could be transferred between adjacent PNNRs in a given direction just by rotating the polarization of incident beam due to unbalanced potential. The angular dependent distribution of electric field around PNNR has been solved using the three- dimensional finite-difference time-domain (FDTD) technique. For optical enhanced catalytic activity, the spectral properties of dimers of Au nanorod-Au nanorod nanostructures under the excitation of 532nm photons have been investigated. With a super-resolution catalytic mapping technique, we identified the existence of "hot spot" in terms of catalytic reactivity at the gap region within the twined plasmonic nanostructure. Also, FDTD calculation has revealed an intrinsic correlation between hot electron transfer.
With the increasing demand for information, integrated silicon photonics technology has been highly valued. Among
them, silicon on insulator (SOI) has advantages of low cost, process maturity, and IC technology compatible, making
it to be one of the most competitive integrated optoelectronic platforms. However, due to its highly
polarization-dependent performance, polarization-selective devices are essential on SOI platform. In this paper, we
analyze the critical guiding condition of SOI waveguide as well as the hybrid plasmonic waveguide (HPW). Based
on the different critical guiding condition for both polarizations, we propose several polarization-selective devices on
SOI platform, including polarizer, polarization beam splitter (PBS) and polarization rotator. In this paper, an
ultracompact and broadband TE-pass polarizer based on HPW is proposed. In addition, an asymmetrical coupling
based polarization beam splitter is designed. Simulation results show that the designed devices have excellent optical
properties, and the sizes of the devices achieve a great breakthrough.