Mimicking a negative refractive slab by combining two phase conjugators

Abstract

A new route toward a lossless superlens has been proposed recently. It relies on the association of two phase-conjugating sheets. The aim of this study is to show how such a lens can be implemented experimentally at optical frequencies. Because efficient phase conjugation of evanescent waves is illusory with the current technology, only the case of propagating waves is considered here. Four wave mixing in BaTiO3 is shown to provide efficient backward and forward phase conjugation over a major part of the angular spectrum, taking advantage of internal reflections inside the non-linear slab. However, phase distortions arise for high spatial frequencies and limit the resolving power of the device. The addition of a second phase-conjugator automatically compensates for these phase distortions. The wave field is then perfectly translated through the system. Actually, such a device performs even better than a negative refracting lens since the association of two phase-conjugating mirrors behaves like a resonant cavity. An amplification of the wave field by a factor of 102 in intensity is predicted, despite the important absorption in BaTiO3.