N. Piovella et al., UP FREQUENCY-CONVERSION IN A 2 RESONANT WAVE FREE-ELECTRON LASER, Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment, 341(1-3), 1994, pp. 196-199
In a free electron laser there are two different resonant frequencies,
with positive and negative slippage. In free space these frequencies
are widely different, but they move together when a waveguide is used
to control the slippage. We investigate the waveguide operation in the
high gain regime and we describe the nonlinear interaction between th
e two resonant waves by a set of partial differential equations. We sh
ow that by injecting a signal at the lower resonant frequency, strong
bunching and signal at the upper frequency can be obtained. This up fr
equency conversion process is maximum when the frequency ratio is an i
nteger number, which can be in principle arbitrarily large.