SC155 Ultrashort Laser Pulse Measurement

Tuesday, May 18, 2010
1:30 p.m.–5:30 p.m.
Pamela Bowlan; Georgia Tech, USA
Level: Intermediate (prior knowledge of topic is necessary to appreciate course material)


Course Description

Probably no field in science and technology is beset by more confusion and misconceptions than that of the measurement of ultrashort laser pulses. There are several reasons: the events involved are unimaginably short, most measurement techniques yield results that can’t be confirmed and competition is fierce to sell lasers or claim world records for generating the shortest pulses. Worse, obsolete techniques introduced decades ago continue to find common use, despite their uninformative and misleading nature. In addition, new techniques are introduced frequently, and most don’t actually work!

Interestingly, most ultrashort-pulse measurement problems have now been solved, and the techniques are accurate, reliable, convincing and easy to work with. This course is designed for anyone who would like to learn how to (correctly!) measure ultrashort laser pulses using techniques that work. It will begin by describing the basics of ultrashort laser pulses and answer the question: what characteristics of them do we need to measure? It will then describe earlier methods (autocorrelation) and why they are now obsolete. Finally, it will consider newer methods: some that work and some that don’t, and why. It will cover a combination of spectrographic and interferometric methods for measuring almost any pulse that can be generated, from few-femtosecond, near-single-cycle pulses to noisy trains of the most complex pulses ever generated.


Benefits and Learning Objectives

This course should enable you to:

  • Explain the fundamental mathematics and physics behind these methods.
  • Measure almost any ultrashort pulse.
  • Verify that your measurement is correct.
  • Measure ultrafast polarization variation.
  • Measure the complete spatio-temporal electric field of a focused pulse.
  • Measure the complete spatio-temporal electric field of an unfocused ultrashort pulse on a single shot using only two optical elements.
  • Discuss how to determine which technique is right for your application.

Intended Audience

Anyone using ultrashort pulses for any reason will find this course useful. Anyone interested in why as seemingly obscure a mathematical fact as the failure of the Fundamental Theorem of Algebra for polynomials of two variables can be responsible for a wide range of successful techniques for measuring ultrashort pulses will also enjoy the course.


Biography

Pamela Bowlan has worked in Rick Trebino's ultrafast optics group at Georgia Tech for the past 6 years. She received her PhD in May of 2009 for developing techniques for measuring very complex ultrashort pulses in both space and time. This year she has continued in the group as a Swamp Optics Research Fellow and has been developing a single-shot nanosecond FROG. She was a winner of the "Student Paper Presentation" contest at Frontiers in Optics in 2008 and her measurements of Bessel-X pulses were featured in the special issue of Optics and Photonics News "Optics in 2009". In August she will begin a post-doc position in Thomas Elsaesser's group at the Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy.