P Radhakrishnan

Design and development of diaphragm-based EFPI pressure sensor

An extrinsic fabry-perot interferometric pressure sensor is fabricated using a cavity formed by a metal diaphragm and a single mode optical fiber. The compact sensor probe has been tested for static pressure response using diaphragms of different metals.

Two photon absorption in TeO2-ZnO glass at different laser irradiances

TeO2-ZnO glasses were prepared and their optical properties were determined. In the present work we measured the optical non-linearity of the glass using a single beam z-scan technique given by Sheike Bahe et al. The open aperture z-scan curve of TeO2-ZnO proves that nonlinear optical properties are highly fluence dependent.

Multipolar second-harmonic generation from films of chalcogenide glasses

Chalcogenide glasses are amorphous semiconductors with a number of interesting properties required for photonic devices. Particularly, their optical properties can be tuned through the change of the glass composition. We investigate second-order nonlinear optical properties of chalcogenide glass (Ge27Se64Sb9) thin films fabricated by thermal evaporation. The strong second-harmonic generation observed for the samples investigated is analyzed as a function of incident polarization. Furthermore, the role of multipole effects in second-harmonic generation is also studied by using two beams at the fundamental frequency. Our results suggest that the higher-multipole effects are present and contribute significantly to the second-harmonic response of chalcogenide the samples.

A Simple Fluorescence based Optical Fiber sensor for Fluoride ions

Fluorescence based fiber optic sensor for fluoride in acetonitrile is implemented using Curcumin dye as the sensing reagent.Curcumin complexes with fluoride ion leading to considerable decrease in fluorescence intensity with increase in fluoride ion concentration

Comparison of Thermal and Refractive index Sensitivity of Symmetric and Antisymmetric modes of Long Period Fiber Gratings

We present the fabrication of LPFGs in single mode standard telecommunication fiber (SMF‐28) using electric arc and CO2 laser irradiation. The thermal and refractive index sensitivities of the antisymmetric cladding modes of the fabricated LPFGs were calculated and compared with that of the symmetric modes of a UV written LPFG. The electric arc induced, periodically tapered LPFG shows temperature insensitive refractive index sensitivity which make them an ideal candidate as a refractometric transducer.

Thermal and nonlinear optical properties of Triazatriangulenium salt for applications in all-optical switches

The nonlinear optical properties of triazatriangulenium salt have been investigated using open aperture and closed aperture configuration of transmission Z-scan experiment. The nonlinear absorption coefficient, nonlinear refractive index and third-order susceptibility was calculated. The thermal properties of the salt has been studied using dual beam mode matched thermal lens technique and the thermal diffusivity of the salt has been measured. With the results obtained we propose that the triazatriangulenium salt could be exploited in all-optical switching applications.

Study of second-harmonic generation from CdS nanostructured thin film

We investigate second-order nonlinear optical properties of a nanostructured cadmium sulfide thin film by optical second-harmonic generation. The relative values of the components of the second-order susceptibility tensor are found to be Xxxz=0.14 and Xzxx=0.07

Solvent Effects on Lasing Characteristics for Rh B Laser Dye

The laser emission characteristics of Rhodamine B dye dissolved in various solvents such as ethanol, butanol and glycerol were studied.The average mode spacing observed was 0.09 nm which was in good agreement with computed data.

Effect of gold nanoparticles doped PEDOT:PSS in polymer light emitting diodes

In the present work, we compare the performance of polymer light emitting devices by incorporating gold nanoparticles in a widely used hole transporting polymer PEDOT:PSS [Poly(3,4-ethylenedioxythiophene) Polystyrene sulfonate]. The results reveal the enhanced conductivity in devices doped with nanoparticles in PEDOT:PSS. Our findings propose gold nanoparticles as effective additives to increase the electrical conductivity of PEDOT:PSS in polymer LEDs.

A Chitosan coated Fiber Optic Long Period Grating Biosensor for the Detection and Estimation of Cholesterol

A Fiber Optic sensor for the measurement of cholesterol has been designed and developed. The chitosan coated LPG sensor developed, showed good stability, repeatability and linear response, which is desirable for a commercial cholesterol sensor.