This paper presents a novel device for add-drop multiplexing. The device is based on a Bragg grating-assisted multimode-interference (MMI)-coupler. The paper also presents computation results and design rules for this promising kind of add-drop multiplexer. The computation is based on the mode propagation theory. SiO2/Si is probably the most convenient technology for realizing this kind of device.
Torsten Augustsson, "Bragg Grating-Assisted MMI-Coupler for Add-Drop Multiplexing," J. Lightwave Technol. 16, 1517- (1998)