SURFACE PLASMON ENHANCED PHOTOLUMINESCENCE ON BIHARMONIC GRATING STRUCTURE

We compare the fluorescence enhancement from a conducting polymer film placed on top of a sinusoidal and biharmonic metallic grating. On the biharmonic grating, which possesses a surface plasmon polariton band-gap, the enhancement factor was larger than that on a sinusoidal grating, even though the coupling efficiency of the surface plasmon polariton was lower for the biharmonic grating. We investigate the mechanism of fluorescence enhancement numerically by finite difference time domain analyses and attribute the larger fluorescence enhancement to the electric field of the short wavelength band-edge mode extending longer into the dielectric region where the fluorophore is placed.

Pyrometric Method of Temperature Measurement with Compensation for Solar Radiation

Pyrometric Method of Temperature Measurement with Compensation for Solar RadiationOutdoor remote temperature measurements in the infrared range can be very inaccurate because of the influence of solar radiation reflected from a measured object. In case of strong directional reflection towards a measuring device, the error rate can easily reach hundreds per cent as the reflected signal adds to the thermal emission of an object. As a result, the measured temperature is much higher than the real one. Error rate depends mainly on the emissivity of an object and intensity of solar radiation. The position of the measuring device with reference to an object and the Sun is also important. The method of compensation of such undesirable influence of solar radiation will be presented. It is based on simultaneous measurements in two different spectral bands, shor-twavelength and long-wavelength ones. The temperature of an object is derived from long-wavelength data only, whereas the short-wavelength band, the corrective one, is used to estimate the solar radiation level. Both bands were selected to achieve proportional changes of the output signal due to solar radiation. Knowing the relation between emissivity and solar radiation levels in both spectral bands, it is possible to reduce the measurement error several times.

S-BAND BRILLOUIN/ERBIUM FIBER LASER FOR DWDM APPLICATION

A multi-wavelength Brillouin erbium fiber laser (BEFL) which operates in a short wavelength band (S-Band) is demonstrated using a depressed cladding erbium-doped fiber (EDF). Two 80/20 couplers were used in the system for internal feedback of generated stokes signal in order to produce cascaded Brillouin stokes for multi-wavelength operation. It generates an optical wavelength comb with spacing of approximately 0.084 m. A stable output laser of up to 7 lines was obtained with a Brillouin pump of 3.5 mW, a 980 nm pump laser of 200 mW and an EDF length of 20 m. The BEFL has the potential to be used in the future dense wavelength division multiplexing (DWDM) communication system.

Effects of Radiative Transfer Modeling on Transient Temperature Distribution in Semitransparent Glass Rod

This paper presents a method of modeling the radiative energy transfer that takes place during the transient of joining two concentric, semitransparent glass cylinders. Specifically, we predict the two-dimensional transient temperature and heat flux distributions to a ramp input which advances the cylinders into a furnace at high temperature. In this paper, we discretize the fully conservative form of two-dimensional Radiative Transfer Equation (RTE) in both curvilinear and cylindrical coordinate systems so that it can be used for arbitrary axisymmetric cylindrical geometry. We compute the transient temperature field using both the Discrete Ordinate Method (DOM) and the widely used Rosseland’s approximation. The comparison shows that Rosseland’s approximation fails badly near the gap inside the glass media and when the radiative heat flux is dominant at short wavelengths where the spectral absorption coefficient is relatively small. Most prior studies of optical fiber drawing processes at the melting point (generally used Myers’ two-step band model at room temperature) neglect the effects of the spectral absorption coefficient at short wavelengths λ<3μm. In this study, we suggest a modified band model that includes the glass absorption coefficient in the short-wavelength band. Our results show that although the spectral absorption coefficient at short wavelengths is relatively small, its effects on the temperature and heat flux are considerable.