Jaison Peter

Microring lasing from a dye-doped polymer-coated silica fiber

We demonstrate pulsed, photopumped multimode laser emission in the visible spectral range from cylindrical microcavities of dye-doped thin polymer film deposited on silica core optical fiber. The laser emission is characterized by narrow emission lines (~0.05 nm), a well-defined excitation threshold and high Q ~ 1.2 × 104. We observed two different sets of resonant laser modes: namely, waveguided ring modes in the polymer film and whispering gallery modes close to the optical fiber surface.

Prototype archival tags for studying the migratory routes of tuna

Archival electronic tags can be used for studying the migratory patterns of tuna, identifying their feeding and spawning grounds, etc. The size of the tag has to be miniaturized, to the extent possible so that by way of attaching such devices the swimming and natural behaviour of the tagged species remain unaffected. The design and development prototype archival tags for sampling the physical parameters of the ocean such as pressure, temperature and light intensity at preset intervals of time is presented in this paper. The tag has been encapsulated and its performance validated in the laboratory as well as in an open test facility in a reservoir.

Angular dependent light emission from planar waveguides

We have investigated the angular dependence of amplified spontaneous emission (ASE) and laser emission from an asymmetric and free-standing polymer thin films doped with rhodamine 6G, which is transversely pumped by a pulsed Nd:YAG laser. A semi-leaky waveguide or quasi-waveguide structure has been developed by spin coating technique. In these waveguides, the light was confined by the film/air-film/glass substrate interfaces. At the film/substrate interface, a portion of light will reflect back into the film (guided mode) and the remaining refracted to the substrate resulting in cutoff modes. A blue-shift in ASE has been observed when the pump power was increased from 8 to 20 mW allowing a limited range of tuning of emission wavelength. To study the directionality of the ASE from the waveguide, we have measured the output intensity and FWHM of emission spectra as a function of viewing angle (θ) from the plane parallel to film. From the detailed examination of the output emission spectra, as +θ increases f...

Impact of laser ablated gold nanoparticles on absorption and fluorescence of Rhodamine 6G in Methyl Methacrylate

In the present work, we investigated the influence of laser ablated gold nanoparticles on the absorption and fluorescence spectra of Rhodamine 6G in Methyl Methacrylate. The absorption peak of Rhodamine 6G in Methyl Methacrylate has enhanced and the fluorescence peak has quenched in the presence of gold nanoparticles due to Fluorescence Resonance Energy Transfer. Also the wide absorption peak due to Surface Plasmon Resonance peak of gold nanoparticle in Methyl Methacrylate has split into two with a complete red shift in the presence of Rhodamine 6G.

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.

Characteristics of Whispering Gallery Mode Laser Emission from Free-standing Cylindrical Microcavity

In this paper, we demonstrate a pulsed, multimode narrow laser emission in the visible spectral range from free-standing cylindrical microcavities formed by dye doped hollow polymer optical fiber photopumped by Nd:YAG laser. The characteristics of multimode laser emission with different pump powers have been also studied. The laser was characterized by narrow emission lines (∼ 0.06 nm), reduced mode spacing (∼ 0.12 nm) and high quality factor, Q (> 9×103) and exhibit threshold excitation intensity of as low as 4 mW. The observed modes are whispering gallery modes close to the optical fiber surface.

A high‐resolution pressure tag for ocean depth measurements.

Data Storage Tags form an important class of electronic tags, used for studying the migratory patterns of highly migratory marine species. In such tags, the parameters to estimate the position of the species are recorded in the tag memory and are retrieved subsequently upon recapturing the tag. The vertical and spatial migration of such marine species can be analyzed in detail using the pressure measurements made by the tags. The migratory behavior of marine species can be attributed to the light intensity variations and temperature profile as well as the search of food and suitable environmental conditions. The depth measurements can be made more accurate, if the resolution of the pressure sensor is significantly high. An absolute pressure measurement with a resolution of 1.2 mbar (approx. 1.2 cm in depth measurements) has been achieved with a pressure tag, capable of recording pressures at preset time intervals. Conversion of the hydrostatic pressure measurements into linear depth variation is carried out using the well‐known equations. Pressure measurements were carried out using the pressure tag in the laboratory conditions as well as in the open ocean and the depth variations were computed using a user‐friendly interactive software.Data Storage Tags form an important class of electronic tags, used for studying the migratory patterns of highly migratory marine species. In such tags, the parameters to estimate the position of the species are recorded in the tag memory and are retrieved subsequently upon recapturing the tag. The vertical and spatial migration of such marine species can be analyzed in detail using the pressure measurements made by the tags. The migratory behavior of marine species can be attributed to the light intensity variations and temperature profile as well as the search of food and suitable environmental conditions. The depth measurements can be made more accurate, if the resolution of the pressure sensor is significantly high. An absolute pressure measurement with a resolution of 1.2 mbar (approx. 1.2 cm in depth measurements) has been achieved with a pressure tag, capable of recording pressures at preset time intervals. Conversion of the hydrostatic pressure measurements into linear depth variation is carried o...