On two-idler parametric amplifiers (Correspondence)

The bandwidth characteristics of two-idler parametric amplifiers are investigated, and an approximate equivalent circuit derived. It is shown that under certain conditions the input impedance Z
_in
is nearly constant and independent of pump amplitude over a relatively wide bandwidth. Computer analysis of particular one- and two-idler amplifiers has yielded comparable bandwidths and noise figures for a single-idler amplifier with a compensating resonator at its input, and a twoidler amplifier. Measured results are given for an experimental two-idler amplifier.