Research

Gautam Vemuri's research covers the general area of laser physics and nonlinear optics, with emphasis on two distinct topics - the statistical and nonlinear dynamical properties of lasers, and quantum effects that arise from light propagation in evanescently coupled waveguide arrays. Semiconductor lasers, despite their low cost, compact size, and wide wavelength tunability, suffer from a major drawback that a weak optical feedback into the laser destabilizes them and the output intensity becomes erratic. A major portion of Dr. Vemuri's work is devoted to elucidating these. The current experimental and theoretical effort is on understanding the nonlinear dynamics of diode lasers subject to two spectrally filtered optical feedbacks with special attention to the frequency dynamics of the lasers.  On the topic of diffraction management in waveguide arrays, current work is on understanding the physics that arises from competition between wave interference, boundary effects in finite lattices, and disorder.  Studies on Anderson localization of light, Bloch oscillations, and PT-symmetry are undertaken in pursuit of this goal.

There is also a substantial theoretical component to our work, where the current focus is on controlling the characteristics of optical pulses via various atomic coherence and interference effects. Such carefully engineered pulses, with desired parameters, are necessary for optical communication systems, as well as for experiments that test the fundamental principles of quantum physics.

The Optical Physics Lab at IUPUI is equipped with an argon laser pumped Ti:Sapphire laser, several ultra-stable diode lasers, Erbium doped, ring fiber laser, digital oscilloscopes and transient digitizers, high-finesse optical cavities, data acquisition systems interfaced to computers and a host of other state-of-the-art laboratory equipment.

Education

• 1990 Ph.D. Physics, Georgia Institute of Technology.
• 1986 M.S. Physics, Brown University.
• 1984 B.Sc. (Honors) in Physics, Delhi University, India.

Publications & Professional Activity

1. V. Pal, J. Suelzer, A. Prasad, G. Vemuri and R. Ghosh, IEEE J., (2013). Semiconductor Laser Dynamics with Two Filtered Optical Feedbacks, Quantum Electronics 49, 340-349
2. Y.N. Joglekar, C. Thompson, D. D. Scott and G. Vemuri, (2013). Optical Waveguide Arrays: Quantum Effects and PT-Symmetry Breaking, Eur. Phys. Journal Appl. Physics 63, 30001.
3. A, Coens, M. Chakaroun, A.P.A. Fischer, M.W. Lee, A. Boudrioua, B. Geffory, G. Vemuri, (2012). Experimental Optimization of the Optical and Electrical Properties of a Half-Wavelength –Thick Organic Heterostructure in a Microcavity, Optics Express. 20, 29252-29259.
4. C. Thompson, Y.N. Joglekar and G. Vemuri, (2012). Disorder Effects in Tunable Waveguide Arrays with Parity-Symmetric Tunneling, Phys. Rev. A86, 043822.
5. C. Thompson, G. Vemuri and G.S. Agarwal, (2011).  Quantum Physics Inspired Optical Effects in Tight-Binding Lattices:  Phase-controlled Photonic Transport, Phys. Rev. B84, 214302.
6. Y.N. Joglekar, C. Thompson and G. Vemuri, (2011).  Tunable waveguide lattices with non-uniform, parity symmetric tunneling, Phys. Rev. A83, 063817.
7. C. Thompson, G. Vemuri and G.S. Agarwal, (2010).  Anderson Localization with Second Quantized Fields in a Coupled Array of Waveguides, Physical Review A82, 053805.
8. Erzgraeber H, Krauskopf B, Lenstra D, Fischer APA and Vemuri G (2007).  Feedback Phase Sensitivity of a Semiconductor Laser Subject to Filtered Optical Feedback: Experiment and Theory.  Phys. Rev., E76, 026212.
9. Erzgraeber H, Krauskopf B, Lenstra D, Fischer APA and Vemuri G (2006).  Frequency Versus Relaxation Oscillations in a Semiconductor Laser with Coherent Filtered Optical Feedback.  Phys. Rev., E73, 055201(R).
10. Fischer APA, Yousefi M, Carter MW and Vemuri G (2004).  Experimental and Theoretical Study of Semiconductor Laser Dynamics Due to Filtered Optical Feedback.  IEEE Journal of Selected Topics in Quantum Electronics, 10, 944-954.
11. Fischer APA, Yousefi M, Lenstra D, Carter MW and Vemuri G (2004).  Filtered Optical Feedback Induced Frequency Dynamics in Semiconductor Lasers.  Physical Review Letters 91, 023901.
12. Yousefi M, Lenstra D and Vemuri G (2004).  Shot Noise has a Significant Influence on the Nonlinear Dynamics of Semiconductor Lasers.  IEEE Journal of Selected Topics in Quantum Electronics, 10, 955-960.