| We studied optical pulse compression of the Vanderbilt FEL in the 3-micron region. In most cases, the optical pulse was stretched instead of compressed. We have demonstrated that these results are in part due to interaction of the FEL with chirped electron micropulses and in part due to difficulties with the compression of ∼1-ps long FEL micropulses. Similar optical pulse stretching, which was suspected of overcompression, has been observed in the FEL optical pulse compression experiment performed at Duke University after our measurements were completed.; However, we have been successful in analyzing the spectral and temporal properties of the Vanderbilt FEL electron and optical micropulses. Measurement and analysis of the Vanderbilt FEL electron micropulse has lead us to a publication. Along the way we have invented an autocorrelation technique for measuring the FEL optical pulse between 2–7 μm, which has also been published. In addition, we have measured non-linear absorption coefficients of Germanium and Indium Arsenide as part of the justification of our new autocorrelation technique. |
