OCDMA coding : decoding system based on superstructured fiber gratings

The area of Optical Code Division Multiple Access (OCDMA) systems has received steadily growing interest in recent years [l-S]. OCDMA offers a number of attractive features for future local area networks including higher connectivity, asynchronous multiple-access and more flexible bandwidth management. Much of the increased activity in this area has resulted from improvements in Fiber Bragg Grating (FBG) fabrication technology driven mainly by the stringent requirements of DWDM. It is now possible to design and reliably fabricate superstructured FBGs with truly complex amplitude and phase responses [9], opening up the possibility of using FBG components to perform fundamental OCDMA functions such as the coding and decodin, 0 of chip patterns described herein. Superstructured gratings offer advantages in terms of compactness, scalability, integrability, cost and ease of manufacture relative to competing technological approaches. These alternative approaches include the use of: arrayed waveguide gratings [Z], fiber delay line arrays [3], arrays of discrete FBGs [4], and bulk-grating based systems incorporating some form of spatial light modulator [5].