Optical parametric amplification and oscillation assisted by low-frequency stimulated emission

Optical parametric amplification and oscillation provide powerful tools for coherent light generation in spectral regions inaccessible to lasers. Parametric gain is based on a frequency down-conversion process and, thus, it cannot be realized for signal waves at a frequency omega(3) higher than the frequency of the pump wave omega(1). In this Letter, we suggest a route toward the realization of upconversion optical parametric amplification and oscillation, i.e., amplification of the signal wave by a coherent pump wave of lower frequency, assisted by stimulated emission of the auxiliary idler wave. When the signal field is resonated in an optical cavity, parametric oscillation is obtained. Design parameters for the observation of upconversion optical parametric oscillation at lambda(3) = 465 nm are given for a periodically poled lithium-niobate (PPLN) crystal doped with Nd3+ ions.