Physics Colloquium, May 13, 2008
Controlling ultrashort laser pluses for biomedical, industrial and analytical applications Marcos Dantus

Michigan State University

Femtosecond laser sources have proven superior for a number of applications such as micromachining, biomedical imaging, mass spectrometry, communications, remote sensing, and even nuclear fusion. The laser-sample interaction depends on the pulse characteristics, primarily the spectral phase which determines pulse duration and every nonlinear optical process induced by the pulse. Based on the fundamental nonlinear optical response to spectral phase modulation we have developed the most accurate method for automated pulse characterization and phase correction [1]. This method has allowed us to eliminate phase deformations in laser systems with pulse durations as short as 4 fs, and pulse intensities as high as 6 mJ/pulse. Having laser systems that can deliver precisely shaped femtosecond pulses has allowed us to achieve a number of significant developments, such as: selective nonlinear optical excitation in two photon microscopy [2], functional imaging through scattering biological tissue [3], controlled nanophotonic emission, multidimensional molecular recognition [4], and optimization of laser micromachining. This presentation will first introduce the principles of nonlinear optics induced by ultrashort (ultra-broad bandwidth) pulses and then illustrate a number of applications.

1. Xu, J. M. Gunn, J. M. Dela Cruz, V. V. Lozovoy, M. Dantus, " Quantitative investigation of the MIIPS method for phase measurement and compensation of femtosecond laser pulses," J. Optical Society B 23, 750-759 (2006); M. Dantus, V.V. Lozovoy, and I. Pastirk, " MIIPS characterizes and corrects femtosecond pulses," Laser Focus World 43, 101-104 Feature Article, (2007).

2. I. Pastirk, J. M. Dela Cruz, K. A. Walowicz, V. V. Lozovoy, and M. Dantus, " Selective two-photon microscopy with shaped femtosecond pulses ." Optics Express 11, 1695 (2003); P. Xi, Y. Andegeko, L. R. Weisel, V. V. Lozovoy, M. Dantus, " Greater Signal and Less Photobleaching in Two-Photon Microscopy with Ultrabroad Bandwidth Femtosecond Pulses," Opt. Commun. 281, 1841-1849 (2008).

3. J. M. Dela Cruz, I. Pastirk, M. Comstock, V.V. Lozovoy, and M. Dantus, " Use of coherent control methods through scattering biological tissue to achieve functional imaging," Proceedings of the National Academy of Sciences USA 101,16996-17001 (2004)

4. J. M. Dela Cruz, V. V. Lozovoy and M. Dantus, " Isomer Identification by Mass Spectrometry with Shaped Femtosecond Laser Excitation," J. Phys. Chem. A 109, 8447-8450 (2005)

Dr. Dantus' Web Site

4:00 p.m., Physics Research Building (PRB), Room 1080

Reception at 3:45 p.m., Atrium, PRB