High-Order Sideband Generation

High-order sideband generation is a phenomenon that occurs when an electron/hole pair called an exciton is ripped apart and smashed back together by intense THz frequency light generated by the UCSB FEL.  Before this occurs, the exciton is created in a sample of GaAs by hitting it with a near-infrared laser.  The kinetic energy added to the exciton by the FEL pulse is released as sidebands occurring alongside the near-infrared light that originally created the exciton.  The old setup for detecting these sidebands could only measure one frequency at a time.  It took an extraordinarily long time to collect data for a full spectrum.  We would like to collect full spectrum data for a very large number of scenarios to see how HSG behaves under different conditions so we needed a new way to collect data in bulk.  We are now using a CCD spectrometer that allows us to measure a large range of frequencies quickly and simultaneously.  This summer, I created a LabVIEW virtual instrument that controls the CCD spectrometer, downloads the data from the CCD, and processes it into a format that is easy to store and analyze.  The new hardware combined with my VI take the average time to collect data on a full spectrum from 4 hours down to about 40 seconds.  We are now able to take about 360 times as data in the same period of time.