Gautam Vemuri
Professor and Chairman

Email Dr. Vemuri

Education

B.Sc. (Honors), Physics, St. Stephen's College, Delhi University, 1984
M.S. Physics, Brown University, 1986
Ph.D., Physics, Georgia Institute of Technology, 1990

Research

Our work is in the general area of laser physics and nonlinear optics, with emphasis on two distinct topics - the statistical and nonlinear dynamical properties of lasers, and biodemical optics. Semiconductor lasers are the lasers of choice for a vast array of applications - ranging from the mundane supermarket scanners to the sophisticated communication systems - primarily because of their low cost, compact size, and wide wavelength tunability. Despite these obvious advantages, these lasers suffer from a major drawback - the presence of very weak optical feedback into the laser destabilizes them and the output intensity becomes erratic. The fundamental causes for this feedback sensitivity are poorly understood, and a major portion of our work is devoted to elucidating these.

My lab, in a collaboration with the Mayo Clinic, is also working in the area of biomedical imaging, with special emphasis on using optical second harmonic generation for imaging of live, unlabeled cells. Unlike other techniques for microscopy and biological imaging, the use of second harmonic imaging enables one to view dynamical processes within the cell, and hence the potential for this technique is quite high.

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.

Publications

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.

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).

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.

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.

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.