The cascaded exponential-tapered multimode interference couplers based triplexer design for FTTH system

A novel compact triplexer, which consists of series cascaded exponential-tapered multimode interference couplers, is introduced in this paper. General self-image properties of the exponential-tapered multimode interference couplers are investigated thoroughly to fulfill the compact integrated triplexer. By combining four exponential-tapered MMI couplers, a novel compact 0.6 cm-long triplexer that is with ITU standard wavelength of 1310 nm, 1490 nm and 1550 nm for FTTH is achieved without requiring complicated design. And it can be fabricated by common planar lightwave circuit (PLC) technology. From the simulation results for wavelength of 1310 nm, 1490 nm and 1550 nm, the insertion losses are 0.34 dB, 0.9 dB and 1.17 dB, with isolations for each output waveguide ranging from 12.74 dB to 37.15 dB. The 3 dB passband widths for 1310 nm, 1490 nm and 1550 nm are 112.39 nm, 29.44 nm and 26.7 nm.