The nano-textured surface of black silicon can be used as a surface-enhanced Raman scattering (SERS) substrate. Sputtered gold films showed increasing SERS sensitivity for thicknesses from 10 up to 300 nm, with sensitivity growing nonlinearly from around 50 nm until saturation at 500 nm. At 50 nm, a cross over from a discontinuous to a fully percolated film occurs as revealed by morphological and electrical measurements. The roughness of the Au coating increases due to formation of nanocrystallites of gold. Structural characterization of the black- Si needles and their surfaces revealed presence of silicon oxide and fluoride. The sharpest nano-needles had a tip curvature radius of ~10 nm. SERS recognition of analyte using molecular imprinted gels with tetracycline molecules of two different kinds is demonstrated.
We present a set of practical rules critical for designing and building a modern nanotechnology laboratory, focused
on photonic applications in a cleanroom environment. We show the impacts on time, cost and quality of early
design decisions and its importance on achieving the final fully functional laboratory. Best practice examples are
presented for setting up a modern laboratory/facility, following analysis of the time, cost and quality constraints.
The case study presented is the engineering and architectural solution of the nanofabrication cleanroom facility
in the Advanced Technology Centre at Swinburne University of Technology, Australia. Set of practical rules is
established for the cost and time efficient set up of the nanotechnology facilities for the research and development.
In this paper, we report the excitation of whispering gallery modes (WGM) using a focused evanescent field. A focused evanescent field generated by total internal reflection at the cover glass-air interface was used to induce two-photon absorption in fluorescent polymer microcavities. By using a focused evanescent field it was possible to effectively couple light into the whispering gallery modes by the efficient overlap between the excitation volume and the cavity modes. The recorded whispering gallery mode spectra using an evanescent wave showed up to 38% enhancement in the spectral characteristics.
In this paper, we report on near field optical tweezers using focused evanescent illumination. The intensity pattern of the focused evanescent field has been characterized using a SNOM. The near field trapping efficiency has been experimentally and theoretically investigated using both TEM00 and TEM01 beams. The trapping efficiency was found to be polarization dependent and also changed for the two modes of illumination used. By incorporating the near field and far field optical tweezers one could construct an optical micromanipulation setup with great flexibility and accuracy, which would find applications in optical nanometry. By coupling the techniques like morphology dependent resonance (MDR), one could employ near field tweezers for near field sensing and for characterization of microfluidic channels.
In this paper, we have demonstrated the measurement of the morphology-dependent resonance (MDR) within a laser trapped microsphere excited under two-photon excitation. Both trapping and two-photon excitation are achieved by a single femtosecond pulsed laser beam simultaneously. MDR induced by two-photon excitation has also shown to overcome difficulties in separation of excitation and resonant wavelengths and the inability to confine excitation illumination precisely3. A spectrally resolved image demonstrates that this technique provides an alternative imaging mechanism for near-field imaging and mapping surface tomography.
In this paper we present two-photon excitation of MDR within a doped polymer micro-sphere. Two-photon technology can be used to induce localized physical change in materials. Due to the highly localized nature of two-photon excitation, the induction of MDR into a micro-cavity can be tightly controlled. A clear and easy separation of excitation and resonant wavelengths is inherent under two-photon excitation. It is shown that the adjacent MDR peaks have orthogonal polarized components, and can be controlled by the position of an excitation spot in a micro-sphere. It is also demonstrated that the micro-cavity MDR peaks have a good agreement with Mie scattering theory.
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