[1] Riziotis C,Zervas M N.Design considerations in optical add/drop multiplexers based on grating-assisted null couplers.J Lightwave Technology, 2001,19(1):92～104

[2] Stoll D,Leisching P,Bock H,et al. Metropolitan DWDM: a dynamically configurable ring for the KomNet field trial in Berlin.IEEE Communications Magazine,2001,39(2):106～113

[3] Berthelon L,Audouin O,Bonno P,et al. Design of a cross-border optical core and access networking field trial: first outcomes of the ACTS-PELICAN project.J Lightwave Technology, 2000,18(12):1939～1954

[4] Bin Liu,Shakouri A,Abraham P,et al. Optical add/drop multiplexers based on X-crossing vertical coupler filters.IEEE Photonics Technology Letters, 2000,12(4):410～412