Abstract

With the advent of high peak power integrated laser sources, optical parametric amplification (OPA) can be useful for signal amplification and noise reduction in fiber systems. OPA is induced by mixing a strong pump wave and a signal wave of different frequency in a Kerr medium. The temporal intensity modulation resulting from the beating of the two waves creates a moving index grating via the optical Kerr effect¹. It leads to modulation instability in the temporal domain and to the growth of spectral sidebands around the pump frequency, the so-called four wave-mixing spectrum. As the involved waves experience different group-velocities because of material and modal dispersions and intensity-dependent nonlinear phase shifts, a phase-matching condition is necessary to ensure exponential-like growth of the amplification. Many studies have focused on the theory of parametric amplification in fibers. They led to show the formal equivalence of modulation instability (MI) and four-wave mixing (FWM).²,³

© 1998 Optical Society of America