267 research outputs found
Decomposition of NO studied by infrared emission and CO laser absorption
A diagnostic technique for monitoring the concentration of NO using absorption of CO laser radiation was developed and applied in a study of the decomposition kinetics of NO. Simultaneous measurements of infrared emission by NO at 5.3 microns were also made to validate the laser absorption technique. The data were obtained behind incident shocks in NO-N2O-Ar (or Kr) mixtures, with temperatures in the range 2400-4100 K. Rate constants for dominant reactions were inferred from comparisons with computer simulations of the reactive flow
Characterizing photonic crystal waveguides with an expanded k-space evanescent coupling technique
We demonstrate a direct, single measurement technique for
characterizing the dispersion of a photonic crystal waveguide (PCWG)
using a tapered fiber evanescent coupling method. A highly curved fiber
taper is used to probe the Fabry-Pérot spectrum of a closed PCWG over a
broad k-space range, and from this measurement the dispersive properties of
the waveguide can be found. Waveguide propagation losses can also be
estimated from measurements of closed waveguides with different lengths.
The validity of this method is demonstrated by comparing the results
obtained on a ‘W1’ PCWG in chalcogenide glass with numerical
simulation
Enhanced spontaneous emission rate from single InAs quantum dots in a photonic crystal nanocavity at telecom wavelengths
The authors demonstrate coupling at 1.3 micro m between single InAs quantum dots (QDs) and a mode of a two dimensional photonic crystal (PhC) defect cavity with a quality factor of 15 000. By spectrally tuning the cavity mode, they induce coupling with excitonic lines. They perform a time integrated and time-resolved photoluminescence and measure an eightfold increase in the spontaneous emission rate inducing a coupling efficiency of 96%. These measurements indicate the potential of single QDs in PhC cavities as efficient single-photon emitters for fiber-based quantum information processing applications. [on SciFinder (R)
Liquid-infiltrated photonic crystals - enhanced light-matter interactions for lab-on-a-chip applications
Optical techniques are finding widespread use in analytical chemistry for
chemical and bio-chemical analysis. During the past decade, there has been an
increasing emphasis on miniaturization of chemical analysis systems and
naturally this has stimulated a large effort in integrating microfluidics and
optics in lab-on-a-chip microsystems. This development is partly defining the
emerging field of optofluidics. Scaling analysis and experiments have
demonstrated the advantage of micro-scale devices over their macroscopic
counterparts for a number of chemical applications. However, from an optical
point of view, miniaturized devices suffer dramatically from the reduced
optical path compared to macroscale experiments, e.g. in a cuvette. Obviously,
the reduced optical path complicates the application of optical techniques in
lab-on-a-chip systems. In this paper we theoretically discuss how a strongly
dispersive photonic crystal environment may be used to enhance the light-matter
interactions, thus potentially compensating for the reduced optical path in
lab-on-a-chip systems. Combining electromagnetic perturbation theory with
full-wave electromagnetic simulations we address the prospects for achieving
slow-light enhancement of Beer-Lambert-Bouguer absorption, photonic band-gap
based refractometry, and high-Q cavity sensing.Comment: Invited paper accepted for the "Optofluidics" special issue to appear
in Microfluidics and Nanofluidics (ed. Prof. David Erickson). 11 pages
including 8 figure
Integrated liquid-core optical fibers --- ultra-efficient nonlinear liquid photonics
We have developed a novel integrated platform for liquid photonics based on
liquid core optical fiber (LCOF). The platform is created by fusion splicing
liquid core optical fiber to standard single-mode optical fiber making it fully
integrated and practical - a major challenge that has greatly hindered progress
in liquid-photonic applications. As an example, we report here the realization
of ultralow threshold Raman generation using an integrated CS2 filled LCOF
pumped with sub-nanosecond pulses at 1064nm and 532nm. The measured energy
threshold for the Stokes generation is ~ 1nJ, about three orders of magnitude
lower than previously reported values in the literature for hydrogen gas. The
integrated LCOF platform opens up new possibilities for ultralow power
nonlinear optics such as efficient white light generation for displays, mid-IR
generation, slow light generation, parametric amplification, all-optical
switching and wavelength conversion using liquids that have orders of magnitude
larger optical nonlinearities compared with silica glass.Comment: 4 pages, 3 figure
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