Abstract

Synchronously pumped OPOs or SPOPOs, in the recent past, have been used for generating ultrashort optical pulses of tunable wavelength or for efficient controlling of the pulse compression and their temporal properties have been theoretically investigated (see for example Cheung et al. [1]). A different application could be addressed for the generation of non-classical states and implement demonstration experiments for high sensitivity optical measurements and quantum information protocols. Mono-mode cw OPOs have been already used for this purpose by exploiting the coherence properties of the interaction (i.e. parametric down conversion) between a non-linear medium and strong e.m. fields; in this way, squeezed, correlated, entangled light has been produced in the so-called continuous variable regime. In order to maximize the quantum effects, one needs to optimize the non-linear coupling. This has been achieved, so far, by using either intense pump lasers or resonant cavities. In the first case, due to the fact that parametric process is an almost instantaneous one, femtosecond mode-locked lasers are the best sources because they generate very high peak optical powers with high coherence properties. Therefore, such a sources have been extensively used to generate non classical light either by pumping a parametric crystal or an optical fiber. However in such single-path configurations, perfect quantum properties are obtained only when the pump power goes to infinity. On the other side, intracavity devices produce perfect quantum properties for a finite power, say the oscillation threshold of the device. On the contrary, SPOPO devices take advantage of the effects of both high peak powers and resonant cavity build-up.

© 2007 IEEE