Exploring various quantum optics phenomena through optical field manipulation

Abstract

This thesis presents the study of coherence effects in the Rb atomic media inside the vapor cell by modifying the coupling beam properties. This thesis is divided into two parts: In the first part of it, we focus on the theoretical and experimental study of the absorptive and dispersive properties of Rb atoms. The D2 transition of 87Rb isotope with Λ-type system is considered to study the optical properties of atomic media. The change in electromagnetically induced transparency (EIT) amplitude and the corresponding change in the dispersive spectra in the Λ-type system are observed under various parametric conditions. We used polarization spectroscopy to study the dispersive properties of the media. In polarization spectroscopy, anisotropy is created by the circularly polarized control beam for the linearly polarized probe beam which gives a dispersion like signal. The slope of the dispersion spectra directly gives the group velocity of the probe beam inside the media. Our primary goal is to enhance the optical properties of the Rb atoms by varying various parameters like the temperature of the vapor cell, polarization, and power of the probe and control field, etc. A comprehensive theoretical model is provided using density matrix formalism and solving the Liouville equation. The EIT amplitude increases up to five-fold. In another experiment, the effect of the magnetic field on the dispersive spectra is also observed in both longitudinal and transverse magnetic fields. The results show that the single dispersion spectrum splits into three dispersive subregions. In the second part of it, we discuss our theoretical study on another coherent phenomenon called electromagnetically induced grating (EIG). We used a five-level Mtype system to present the effect of a microwave field on EIG both in one and two dimensions. The microwave field is coupled to the magnetically allowed transition of the atomic system, which enhances the probe diffraction efficiency.