Passive athermal Mach-Zehnder interferometer twin-core fiber optical add/drop multiplexer

We present, for the first time to our knowledge, a totally passive athermal Mach-Zehnder interferometer OADM. Combining Bragg gratings and twin-core fiber fused couplers, this device has less than 1pm//spl deg/C deviation on Bragg wavelength in the -10/spl deg/C to +70/spl deg/C range while maintaining the directivity of the drop and throughput signals.