An unbalanced Mach-Zehnder interferometer made using dissimilar-fibre fused taper couplers is proposed for filtering applications. The all-fibre device is compact, rugged, simple to make and provides extended control and flexibility for the design of various types of filters.
Electronics Letters
Department of Electronics

Albert, J, Malo, B., Bilodeau, F., Hill, K.O., & Johnson, D.C. (1989). Unbalanced dissimilar-fibre Mach-Zehnder interferometer: application as filter. Electronics Letters. doi:10.1049/el:19890945