Vijay Deshmukh

Research during Ph.D. at Inha University Polarization switching dynamics in the VCSEL output via an optical injection locking, including (i) the temporal delay effect in recovery of the original polarization after switching, (ii) optimum operating parameters for reduced delay time and fast recovered polarization, (iii) control mechanisms of the polarization direction of the VCSEL, and (iv) spin-induced ultrafast circular polarization oscillations, are reported. Numerical simulations based on a Spin flip model and experimental investigations are reported. By comparing the numerically calculated results with experimentally observed ones, internal parameters of VCSEL were optimized. External laser pulses of 50-ps full-width at half-maximum (FWHM) were injected into a long-wavelength single-mode (SM) VCSEL at the wavelength of its suppressed side mode, which has an orthogonal polarization to that of the main lasing mode at a slightly separated wavelength. The anisotropies such as birefringence and dichroism are exploited for polarization switching in single-mode VCSEL. The shortest recovery time for main mode polarization recovery, optimized numerically can be useful to design the VCSEL for all-optical switching applications. Numerical simulations based on spin-flip model, have been performed to study spin induced ultrafast circular polarization oscillations. Though the circular polarization oscillation frequency is directly proportional to the birefringence, the upper limit for circular polarization oscillation frequency has been found. It is found that, the limit of modulation bandwidth of VCSEL can be overcome by the circular polarization oscillation frequency. The strongly damped circular polarization oscillations can be used for fast modulation, whereas weakly damped oscillations can have application for clock purpose.

Postdoctoral Research at GIST Photon echo is being extensively studied for its potential applications for future quantum repeater. A scheme for the study of photon echo in N-V center in diamond is proposed. The LabView program was written to perform the scanning of Diamond sample to investigate the positions of NV Centers. The absorption of microwave frequency at 2.87 GHz is observed as a result of excitation of spin from |0> to |±1> states of ground state of nitrogen. Also a scheme for spin manipulation is proposed.