Optical amplification device with noise filter function

Claim 1

An optical amplification device with noise filter function including a body built up from a plurality of layers of different materials, wherein at least a first one of the layers (1, 1a, 12) is a light wave conductor having a first effective index of refraction which varies with wavelength according to a first relationship, at least one further of the layers (5, 5a, 14) is a light wave conductor which can amplify a light wave (I s , I b ) propagating in this further layer and which has a second effective index of refraction which varies with wavelength according to a second relationship different from the first relationship, the second effective index being substantially equal to the first effective index at a predetermined wavelength intended for amplification, further including drive means (8, 8a, 16) for providing an excitation (I, Q) to the at least one further layer, the excitation causing the further layer to become transparent to and to amplify light propagating in the further layer and including light of the predetermined wavelength when the excitation exceeds a predetermined value required to make this further layer (5, 5a, 14) transparent to the light wave, and wherein the light wave conductive layers (1, 1a, 12 and 5, 5a, 14) are optically coupled so that a directional coupler is created, an interaction length (2L) of which is substantially an even number of coupling lengths (L) for the predetermined wavelength, the further layer amplifying light coupling from the first layer and propagating in the further layer and the first and second relationships being selected so that the optical amplification device filters light passing therethrough.