Abstract

Noiseless optical amplification–a non-classical process in which a weak optical signal may be amplified without any degradation in the signal to noise ratio (SNR)–is generating interest in the telecommunications community. Although successfully demonstrated in bulk KTP crystals¹, practical applications are severely hampered by the enormous pump-field strength required to obtain a sizeable gain. Efforts to reduce this requirement are centred on the search for better non-linear materials and stronger confinement of the interacting fields. In this article a noiseless optical parametric amplifier (OPA) is demonstrated with tightly-focused incident fields in quasi-phase-matched (QPM) lithium niobate (LiNbO₃), for the first time. The quantum noise properties are analysed within a quantised field framework which reveals a strong similarity between guided and free wave interactions.

© 1996 Optical Society of America