In-situ Raman and fluorescence measurements were used to detect optically trapped single-walled carbon nanotubes (SWNTs). The in-situ fluorescence technique provides strong indirect visual evidence of optical trapping of SWNTs by monitoring the fluorescence quenching from a solution containing a mixture of carbon nanotubes and a fluorescent dye. The second monitoring technique uses in-situ Raman spectroscopy to show that in the presence of the optical trap, both the profile and the intensity of the nanotube Raman spectrum changes compared to when the optical trap is off. The Raman monitoring setup consists of two lasers which independently create the optical trapping path and Raman probing path. In this technique the Raman probe is capable of detecting structural information of the carbon nanotubes in the optical trap; therefore providing direct evidence of the local SWNTs concentration variation and chirality distribution. Both methods were used to verify optical trapping of SWNT and to determine the trapping threshold, trapping volume profile, and information on tube concentration change during optical trapping.
This report will present a new and highly versatile manufacturing technology, Laser Reactive Deposition (LRDTM) processing, to produce planar glass coatings for planar lightwave circuit (PLC) manufacturing. Planar glasses with a wide range of glass compositions offering various passive and active optical functionalities have been produced using this technology. In particular, LRDTM processing removes a major bottleneck experienced by existing glass fabrication technologies in the high speed deposition of thick and complex glasses. In LRDTM processing, instead of depositing atoms or molecules a layer at a time, nanoscale particles produced in situ are used as fundamental building blocks for planar glass fabrication. The significantly larger mass of these nanoscale clusters in comparison to atoms or molecules has enabled a much higher throughput and lower cost. Optical quality glasses are obtained by a subsequent high temperature consolidation process. The nanoscale particle size and narrow size distribution, uniquely offered by LRDTM processing, are critical for the fabrication of high optical quality planar glass. We have demonstrated in this work that LRDTM processing can produce high quality doped waveguide glasses such as phosphorous-doped silicate glass and UV photosensitive glasses such as germanium-doped silicate glass. We have also demonstrated the capabilities of LRDTM processing in controlling refractive index and layer thickness of the waveguide core to achieve single mode light propagation at 1.55 microns. Finally, we will present characterization results on basic parameters including propagation loss, surface roughness, and refractive index and thickness uniformity on 4 inch planar glass wafers deposited using LRDTM processing.
The nanostructured matrix of porous silicon makes the material an ideal host for erbium because its very large surface area allows easy infiltration of the ions into the matrix and it readily oxidizes obtaining large concentrations of oxygen necessary for erbium emission. Erbium is infiltrated in the pores (<EQ 10-19 cm-3) by cathodic electrochemical migration of the ions followed by high temperature annealing (950 - 1100 degree(s)C). Electrochemical doping of porous silicon by erbium is simpler and of lower cost when compared to conventional techniques like ion implantation, epitaxial growth, and chemical vapor deposition used to fabricate erbium-doped c-Si structures. We demonstrate stable room- temperature electroluminescence at 1.54 micrometers from erbium- doped porous silicon devices under both forward and reverse bias conditions.
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