Frequency-Resolved Optical-Gating

By Alexandra M. Brancale

Supervisor:  Dr. Carlos Trallero

Kansas State University Physics Department  REU Program

This program is funded by the National Science Foundation through grant number PHY-1157044. 

Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

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College of Saint Benedict and Saint John’s University Physics Department MapCores Program

Welcome to my webpage! This summarizes my summer research experience at Kansas State University under Professor Carlos Trallero.

Project Overview:

This summer I worked mostly with the Frequency-Resolved Optical-Gating (FROG) that is to be used in the High Intensity Tunable Source (HITS) Room of the James R. Macdonald Laboratory at Kansas State University. The purpose of a FROG is to record pulse characteristics of a laser beam. The information a FROG produces is very useful in many different experiments that manipulate and control molecules. This is a growing field, and this apparatus can now be used to aid in experiments around the lab.

In order to truly understand what the FROG is doing and how it works, Dr. Carlos Trallero’s group built their own FROG. Another unique aspect of this FROG is that it can be operated in both a single-shot mode and a scanning mode. At the beginning of the summer we decided on some goals in regards to the FROG. We wanted to align the FROG, produce second harmonic light, record pulse characteristics, optimize the LabView program that controls the FROG, trigger the camera shutter properly, and expand the FROG to other wavelengths. The general idea behind the FROG setup is to split a beam, delay half of it, and overlap the two halves in a second harmonic generation (SHG) crystal. Once this overlap takes place, SHG light is produced due to the nonlinear properties of the crystal. In my experience, the light sent into the FROG was 800 nm and the SHG light was 400 nm. The trickiest part of taking data was aligning the FROG properly so that second harmonic light was produced. This only occurs when the two beams are overlapped within the crystal in time and space. Once we found the optimum spot (when the blue light was at its brightest), we took a scan. The scan begins before the optimum spot and ends after, collecting all of the data of the entire pulse overlap. After that data is collected, we enter it into a FROG reconstruction program. This program uses many different algorithms to try to recreate the scan by simulating the electric field of the pulse it read. This program gave us important information about the phase and duration of the overlapped pulses. We found that the HITS FROG and the software that controls the FROG are functioning correctly. We can confidently say this because the pulse duration of the HITS FROG was within two femtoseconds of the pulse duration of the commercially created PULSAR FROG. 

I also worked towards the overall goal of automating the HITS Lab. I made various LabView programs that will be used to monitor and control a number of devices within the lab. The first program I made monitors a Maxi Pressure Gauge. That gauge can be used to determine the pressure in any vacuum chamber in the lab. Another project I worked on was making a program that communicated with a Data Acquisition box. This box has the ability to read and write different voltages with the ultimate goal of sending that information to high voltage power supplies. This program was specifically written for the Velocity Map Imaging experiment in the HITS lab but can easily be applied to any other power supplies. My most recent contribution to the automation of the lab was creating a LabView program that implemented a genetic algorithm library. This genetic algorithm program will be used to control the voltages on plates in an Electron Time of Flight experiment. We needed a genetic algorithm in order to optimize the electron yield on a micro-channel plate.

This summer was a great experience for me! I learned so many valuable things that I would not have had the opportunity to experience if I stayed at my college at home. This lab experience will definitely help me make more informed decisions about what I want to do in my future.


Research Progress Reports:

Progress Report 1 – 6/14/13

Progress Report 2 – 6/28/13

Progress Report 3 – 7/19/13


Final Presentation: 

Final – 8/1/13


Lecture Topics by Dr. Larry Weaver: 

Professor Larry Weave gave around 15 lectures on all different topics of physics from Electromagnetism to Quantum. Just from looking through my notes, some of the topics consist of: blackbodies, wave equations, chemical forces, scattering, Gauss’s law, anti- particles, and Fourier equations. Larry catered the lecture topics to questions we had regarding any of our research projects.   


Ethics Class Topics by Professor Bruce Glymour and Professor Amy Lara:

Class 1: We discussed different popular Ethical theories.

Class 2:  We discussed the Ethics and Values that are adopted by the American Physical Society. We were also introduced to case studies regarding co-authorship and fraud. We began to look at the relationship between graduate students and professors and how ethical problems can arise in those scenarios.

Class3: In this class we focused on plagiarism and defining policy as an individual and as a group.

Class 4: We began by defining frames and how they apply in the sciences. We split up different cases and audiences and shared with the class how we would present the information regarding your case and how you would frame your situation in order to evoke the right feelings for your audience.

Class 5: This discussion was based on comparing the profile of a good scientist and the profile off a bad scientist. We came up with virtues and vices that can be found in scientists and how those characteristics can influence science.

Class 6: We discussed the ethical dilemmas that Physics graduate students go through with their mentors. We also went through many potential scenarios provided by the APS and discussed how we could best handle the situation.

Class 7: This discussion revolved around the concepts of nature and nurture. We talked about inequalities between men and women in the sciences and if actively trying to change the inequalities is fair or just. It is a very interesting topic, and we could have spent the entire course discussing this.

Class 8: In the previous class, we had to each submit a different case of an ethical dilemma that an undergraduate could encounter. In this class we discussed each case and reviewed what would be the best thing to do in each scenario.


Electronics Class by Brian Washburn:

During the 1st class we had a brief introduction to electronics. We reviewed Ohm’s Law, parallel and series rules, diodes, and circuit components. Then we created a voltage divider on a breadboard after discovering how they work.

During the 2nd class we learned about basic passive filters. We applied what we learned by creating a high and low pass filter on the breadboard.

During the final class we learned about amplifiers and their properties. We learned about operational amplifiers and their golden rules by creating different amplifiers on the breadboard. 


Shop Class by Russ Reynolds: 

This class focused on the general safety procedure for the Machine Shop. We also learned how to properly use a drill press, band saw, and surface grinder. Much to my surprise, tapping the hole in the plastic practice piece proved to be the most difficult part of the class!


About Me:  

I grew up in Eden Prairie, Minnesota and attend the College of Saint Benedict in Saint Joseph, MN. I will be a senior Applied Physics and Numerical Computation double major this fall. I first got interested in physics when I toured a laser company in the Twin Cities. During the school year, I work for the St. John’s wrestling team and the Admissions Office as a Tour Guide. I participate in different programs such as MapCores, Orientation, Companions on a Journey, and Benedictine Friends. Last year I had an awesome internship in the Sustainability Office at St. Bens that lead me to a May term study abroad experience in Ecuador.



I want to give a huge thank you to the people who made this summer such a wonderful experience. I want to thank Dr. Carlos Trallero for taking me on to his research team. I especially want to thank Stefan Zigo for helping me and working with me the entire summer. He was a fabulous mentor and never got sick of my questions! I want to thank the rest of Carlos’s group for being fun and helpful when I had questions, Larry Weaver and Kristan Corwin for organizing this program, the JRM support staff for keeping everything working smoothly, the other REU students for helping me when I had questions and keeping the summer entertaining, and the NSF for the grant that gave me this amazing research experience.


Useful Links: 

American Physical Society Statements on Ethics

American Institute of Physics

James R. Macdonald A.M.O. Lab at Kansas State University