Theoretical study of a four-level EIT-type system in the presence of structured coupling light for microwave field detection.

In this work, we have theoretically studied the four-level atomic system for the measurement of a microwave (MW) field. We employed the electromagnetically induced transparency (EIT) technique for finding the MW field in the presence of a Laguerre-Gaussian (LG) beam as a coupling light. We have shown that, by the application of LG modes, narrower dips for the probe absorption spectrum can be generated, which can be easily identified and gives better resolution compared with the Gaussian mode. An exact location of dips in the probe absorption spectrum is found, and it is useful in the measurement of MW fields. We have estimated the FWHM of the probe absorption spectrum for Gaussian and LG coupling cases as 3.74×105 H z and 1.07×105 H z, respectively. Based on FWHM, we have found that minimum change in MW electric field in the order of 3.32µV c m -1 will be detectable in the case of the LG mode as a coupling beam.

Numerical investigations on photonic nanojet mediated surface enhanced Raman scattering and fluorescence techniques.

Finite element method simulations have been carried out on the photonic nanojet (PNJ) mediated surface enhanced Raman scattering (SERS) technique for the first time, and this technique has been found to provide (i) better Raman scattering enhancement of single molecules and (ii) a long working distance between the microscopic objective lens and sample, as compared with the conventional SERS technique. A PNJ mediated surface enhanced fluorescence (SEF) technique has been proposed to enhance the fluorescence of single molecules using the combination of localized surface plasmons inside nanostructures and the PNJ of a dielectric microsphere (MS), and this technique is numerically proved to be efficient as compared with a conventional SEF technique. Moreover, the generation of a PNJ from single lollipop shaped microstructures and its applications in the above mentioned techniques have been reported.

Theoretical design for generation of slow light in a two-dimensional magneto optical trap using electromagnetically induced transparency.

In this paper, we propose a novel technique for slow light experiments using electromagnetically induced transparency using a two-dimensional magneto optical trap (2D-MOT). A compact 2D-MOT design efficient for quantum memory applications with adjustable optical depth (OD) is proposed. We estimated the OD for our 2D-MOT setup and found that light group velocities as low as 1.4 m/s can be attained. Our design for 2D-MOT allows precise control and optimization of the OD such that high storage efficiencies could also be achieved. With our design, it is possible to obtain a delay bandwidth product of 163, which is very high in comparison to previously obtained values.