Signal breathing losses in filters based on optical channel with high index modulation

International audienceIn this paper, the authors demonstrate the existence of a new type of losses later called ’signal breathinglosses’. They have adopted this name because when the optical signal propagates in the propagationchannel it changes its size and its position each half period. These dimensions changes will force the signalto get out from the transmission channel with signal losses and part of its proper power making it lessconfined. They have been able, theoretically and experimentally, to measure small variations in the signalwhich propagates in the optical propagation channel to 3D or in the plans XY, XZ and YZ.Furthermore, the authors measured and quantified the signal breathing losses based on the depth ofcorrugation, the size and of the number of periods. Then they affirmed that this type of loss increases witha significant number of periods, with periods of large dimensions, or disturbances to index modulationcharacterized by important depths. These measures were performed on a set of Bragg filters done onan optical propagation channel of type broadcasted waveguide.The authors believe the ’signal breathing’ phenomenon is similar to that of 2G and 3G wireless systemsincluding code-division multiple access (CDMA) which is the cell breathing phenomenon due to alterationof the data traffic

Spectral coded phase bipolar OCDMA technological implementation thanks to low index modulation filters

International audienceOptical code division multiple access (OCDMA) systems are attracting an increasing interest in optical fiber communication. This is due to the various advantages that they provide; in particular for the simultaneous improvement capacity and flexible channel allocation as well as fastest data speeds and increased security. In this paper, the authors present an experimental demonstration of bipolar optical CDMA System with phase shift using E-beam technique on Hx Li1−x NbO3 transmission channel realized by proton exchange. The idea of the proposed system is to evaluate the result of eight cascaded Bragg filters in very narrow band. The coded sequence corresponds to that of Hadamard H8(7), represented by the bits ’1 1 −1 −1 −1 −1 1 1’, and phase shift have been identified on the coder spectral response whilst increasing the multiplexing capacity in terms of the total number of users and the data