AF1G.6.pdf Asia Communications and Photonics Conferene (ACP) © OSA 2016 J-Rib Waveguide as a Mode-Division Demultiplexer Jideofor A. H. Odoeze, Omnia M. Nawwar, and Hossam M. H. Shalaby Egypt-Japan University of Science and Technology (E-JUST), Alexandria, Egypt jideofor.odoeze@ejust.edu.eg, omnia.nawwar@ejust.edu.eg, shalaby@ieee.org Abstract: A rib waveguide with unequal slab thicknesses, called J-rib waveguide, is proposed as a mode-division demultiplexer. 3D FDTD simulation of the proposed device is performed. Low insertion loss, low crosstalk, and wide bandwidth are achieved. OCIS codes: 130.0130, 130.3120, 130.2790, 230.7370. 1. INTRODUCTION The increasing bandwidth of the future parallel chip multiprocessor to meet up with the current demand in high transmission rate has been promising with the emergence of optical interconnect [1]. Many multiplexing techniques have been used to increase the capacity of systems [2, 3]. Space-Division Multiplexing (SDM) technique increases capacity but it is unsuitable for on-chip applications since it increases footprint due to the fact that each signal has its own path [4]. Wavelength-Division Multiplexing (WDM) technique, that increases capacity without increasing footprint, seems better for on-chip application [5]. The problem of complexity and increase in cost that arises from the use of multiple laser sources for different wavelengths makes WDM also unsuitable for on-chip applications. In Mode- Division Multiplexing (MDM) techniques, each mode of a multimode waveguide is considered as an independent channel that carries data. MDM techniques can increase capacity and reduce footprint. They have shown to be more suitable for on-chip applications [6]. In an MDM system, a mode multiplexer/demultiplexer is one of the important component, as it combines/retrieve data from each modes. Many mode (de)multiplexer have been presented in literature. Dai et al. have demonstrated experimentally a small silicon mode (de)multiplexer with cascaded asymmetrical directional coupler [7]. Gui et al. have fabricated an on-chip two-mode multiplexer/demultiplexer using a tapered asymmetrical grating-assisted contra- directional coupler-based [8]. Dorin and Ye have presented a design and fabrication of a two-mode SOI ring resonator for MDM systems [9]. Shalaby has presented a simple mode-division (de)multiplexer using a bi-directional coupler supported with a Bragg grating [10]. Here, we propose a simple mode-division demultiplexer using only one waveguide, called J-rib. The structure can demultiplex 3 modes with only one waveguide. That is, the structure is simple and compact in size. In addition, we show that the device has low insertion loss and low crosstalk over a wide bandwidth. 2. PROPOSED SYSTEM MODEL Figure 1 shows the structure of the proposed J-rib waveguide. The length of the device is denoted by L. The thicknesses Fig. 1. Structure of J-Rib waveguide.