Low-noise photoparametric up-converter

An analysis is given for a photoparametric up-converter system. The up-converter consists of a single triplate line with one coaxial output connected to a circulator, through which the pump is applied and the signal extracted. The other end of the line is connected to the photo diode via a small coupling capacitor. The light is modulated at frequencies from a few hertz to some upper limit determined by the bandwidth of the triplate circuit. This arrangement is shown to give excellent results and the limit performance, as determined only by the diode parameters may be attained by following the up-converter with a degenerate parametric amplifier using the same pump plus a varactor doubler.