Four-wave mixing of Gigawatt power, Long-wave Infrared Radiation in Gases and Semiconductors

Speaker: Jeremy Pigeon
Affiliation: Ph.D. Candidate - UCLA

Abstract:  The main application of nonlinear optics is the frequency conversion of laser light.  In the process of optical harmonic generation, the entire laser spectrum is converted to a harmonic of the initial field thus producing light at an entirely different frequency.  Self-phase modulation, on the other hand, results in the broadening of the initial laser spectrum as a means to produce ultra-fast pulses or to produce coherent, “white-light” centered about the laser’s carrier frequency. Such sources of “white-light” or supercontinuum are of interest for broadband spectroscopy.

The majority of nonlinear optics experiments have been limited to the visible and near-IR wavelengths (0.4 – 1.5 μm) where high-power laser sources are commercially available. Applications would benefit, however, from extending these studies to longer wavelengths.  The “molecular fingerprint region” from 2 – 20 μm is of particular interest for spectroscopy since many molecules have fundamental rotational-vibrational transitions in this region.

For this dissertation, the nonlinear optics of gigawatt power, 10 µm, 3 and 200 ps long pulses propagating in gases and semiconductors has been studied experimentally and numerically. Here, the development of a high-repetition rate (1 Hz), picosecond, CO₂ laser system has enabled experiments using peak intensities in the range of 1 – 10 GW/cm², approximately one thousand times greater than previous nonlinear optics experiments in the long-wave infrared (LWIR) spectral region. This capability has enabled the first measurements of the nonlinear refractive index of atomic and molecular gases in the LWIR, the demonstration of record-breaking supercontinuum generation from 2 – 20 µm in GaAs pumped by 3 ps 10 µm pulses, and the production of high-power 10 µm pulses by multiple four-wave mixing compression of a CO₂ laser beat-wave propagating in GaAs.

Biography:  Jeremy Pigeon is a Ph.D. candidate in Electrical Engineering studying under Professor Chan Joshi.  Jeremy received his B.S. in Physics and Health Physics from Bloomsburg University of Pennsylvania in 2008 and his M.S. in Electrical Engineering from UCLA in 2014. Jeremy was twice awarded the best student poster prize at the Advanced Accelerator Concepts conference in 2012 and 2014 and was a finalist for the Emil Wolf Student Paper competition at the Frontiers in Optics conference in 2017. Jeremy has authored or coauthored 27 peer-reviewed papers and conference proceedings in nonlinear optics and laser-plasma interactions.

For more information, contact Prof. Chan Joshi (joshi@ee.ucla.edu)

Date/Time:
Date(s) - Oct 06, 2017
2:00 pm - 4:00 pm

Location:
E-IV Tesla Room #53-125
420 Westwood Plaza - 5th Flr., Los Angeles CA 90095