Current Issue : October - December Volume : 2011 Issue Number : 1 Articles : 6 Articles
Under certain conditions, a surface plasmon wave along a metal-dielectric interface can be excited by an optical beam. The reflected optical beam will then undergo changes in both intensity and phase. As the level of intensity or phase change is quite sensitive to the coupling conditions such as the molecule concentration on the metal surface, this phenomenon has been utilized for label-free detection of biological species and characterization of molecular interactions during the last two decades. Currently, most of the commercial surface plasmon resonance (SPR) sensors rely on the detection of absorption dip in angular or wavelength spectrum. However, recent researches have shown that phase detection has the potential to achieve lower limit of detection (LoD) and higher throughput. This paper, thus, intends to review various schemes and configurations for SPR phase detection. The performance advantages and disadvantages of various schemes will be emphasized. It is hoped that this paper will provide some insights to researchers interested in SPR sensing and help them to develop SPR sensors with better sensitivity and higher throughput....
Electrostatic levitation combined with laser heating is becoming a mature technique that has been used for several fundamental and applied studies in fluid and materials sciences (synthesis, property determination, solidification studies, atomic dynamic studies, etc.). This is attributable to the numerous processing conditions (containerless, wide heating temperature range, cooling rates, atmospheric compositions, etc.) that levitation and radiative heating offer, as well as to the variety of diagnostics tools that can be used. In this paper, we describe the facility, highlighting the combined advantages of electrostatic levitation and laser processing. The various capabilities of the facility are discussed and are exemplified with the measurements of the density of selected iron-nickel alloys taken over the liquid phase....
A method for measuring frequencies of the terahertz (THz) radiation emitted by the antenna mounted on the photoconductive (PC) device is presented. Two laser beams with slightly different frequencies irradiate the PC device, producing a beat current of 1?THz in the photocurrent. A microwave signal is applied to the antenna electrode. The frequency of the THz wave is measured using the homodyne detection of the optical beat with the high-order harmonics of the microwave. It is being investigated that the high-order harmonics are produced by the PC device owing to its nonlinearity. Periodic peaks generated by the homodyne detection were observed in the photocurrent, as the microwave was swept from 16 to 20?GHz with a power of -40?dBm. Using the peak frequencies, the THz-wave frequency was determined to be 1 0 3 0 . 3 �± 3 . 7 3\r\n?GHz. The measurement error is estimated to be less than 0.43?GHz. The proposed method realizes a compact frequency meter in the THz region....
The finite-difference time-domain (FDTD) algorithm has been used in simulation-based designs of many optical devices, but it fails to reproduce high-Q whispering gallery modes (WGMs). On the other hand, the nonstandard (NS) FDTD algorithm can accurately compute WGMs and can be used to make simulation-based designs of WGM devices. Wavelength splitters using the coupled resonator optical waveguides (CROWs) based on WGM couplings have recently attracted attention because they are potentially ultracompact. In this paper, we design a CROW wavelength splitter using NS FDTD simulations and demonstrate high interchannel extinction ratios of over 20?dB....
The optical properties of afterglow nanoparticles were successfully improved by the addition of polyethylene glycol (PEG) to an afterglow colloidal solution. Afterglow nanoparticlesââ?¬â?S r2M g S i2O7: E u2 +, D y3 +ââ?¬â?were prepared by laser ablation in liquid. The quantum yields and the decay curves were measured by a fluorescence spectrophotometer. An increase in the amount of PEG added to the solution increased the quantum yield of the nanoparticles and improved the afterglow property in the initial portion of the decay curve. However, the afterglow property did not change after a substantial amount of time had passed. The afterglow nanoparticles were capped with PEG molecules, and surface defects of the nanoparticles were passivated, which decreased the optical properties....
Rare-earth and Bi-substituted iron garnet thin film materials exhibit strong potential for application in various fields of science and frontier optical technologies. Bi-substituted iron garnets possess extraordinary optical and MO properties and are still considered as the best MO functional materials for various emerging integrated optics and photonics applications. However, these MO garnet materials are rarely seen in practical photonics use due to their high optical losses in the visible spectral region. In this paper, we report on the physical properties and magneto-optic behaviour of high-performance RF sputtered highly bismuth-substituted iron garnet and garnet-oxide nanocomposite films of generic composition type (Bi,?Dy/Lu)3(Fe,?Ga/Al)5O12. Our newly synthesized garnet materials form high-quality nanocrystalline thin film layers which demonstrate excellent optical and MO properties suitable for a wide range of applications in integrated optics and photonics....
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