Analysis of Reconfigurable Multi-Channel Wavelength Add Drop Multiplexer for Intelligent Optical Networks S. PONMALAR  and S. SUNDARAVADIVELU 1 Department of ECE, Thiagarajar College of Engineering, Thiruparankundram, Madurai-625015, India 1 Department of ECE, SSN College of Engineering, Old Mahabalipuram Road, Kalavakkam, Chennai-603110, India (Received October 5, 2010; Accepted April 25, 2011) This paper presents design of an electro-optically tunable polymer multi-channel wavelength add drop multiplexer (WADM). The proposed WADM with trapezoidal waveguide geometry and poled electro-optical polymer material in the waveguide cores enables the wavelength tuning speed of WADM as 7.5 ps at the resonance wavelength of 1550 nm and coupling length of 1.5 mm. The device can be electro-optically tuned to add/drop multiple channels. Transmission spectra of the device with varying device parameters are simulated. The proposed WADM with high speed, small size and varying tuning capability makes this device, an important element in faster provisioning and routing of light paths in intelligent optical network. # 2011 The Japan Society of Applied Physics Keywords: intelligent optical network, coupled mode theory, electro optic effect, polymer waveguide add drop multiplexer 1. Introduction With the rapid growth of internet and enterprise applica- tions, the bandwidth demand for data traffic is increasing at exponential rate. The advances in dense wavelength division multiplexing (DWDM) technology have enabled the deploy- ment of such a system that is capable of providing large amount of bandwidth. DWDM system with a data rate of OC-192 and above, a total of 1.6 Tbits/s can be delivered by the optical fiber. Even though, bandwidth provided by these systems is plenty and inexpensive, the carrier’s key challenge is to turn the bandwidth into services for customers in a cost-effective and timely manner which forms the basic motivation for incorporating intelligence into optical networks. Emerging WDM based intelligent optical networks (ION) can establish optical light paths as on demand that enables the service provider to respond to the request quickly and economically. The other reasons to incorporate intelligence in optical network are faster provisioning, protection, restoration, automatic discovery of network elements and automatic reconfiguration of network. 1,2) Existing bandwidth allocation in optical network is static and is time consuming. The new generation of intelligent optical network, enabled by high capacity optical cross connects (OXCs) and reconfigurable optical add–drop multi- plexers with software intelligence grants new methods for automatic provisioning, routing, restoration and manage- ment of high capacity core optical networks quickly. 3) As reconfigurable wavelength add drop multiplexer has become a key device in ION, an effort is made in this paper to analyze the wavelength add–drop multiplexer based on waveguide grating geometry. Several types of add–drop multiplexers based on Mach–Zehnder interferometers, 4) grating-assisted mismatched couplers 5,6) and multiport cir- culators 7) have been reported in literature. The traditional ADM configuration, involves a fiber Bragg grating (FBG) placed between two optical circulators is thought simple to implement, but suffers from unavoidable optical losses. Tang et al. has demonstrated a tunable OADM using a static-strain-induced grating in LiNbO 3 . 8) However the integration of LiNbO 3 on semiconductor electronics is very difficult. In this paper, the performance of wavelength add drop multiplexer in electro optic polymer waveguide gratings has been studied, as the polymer electro-optic material has the advantage of low dispersion in the index of refraction of polymers and flexibility in monolithic integra- tion with semiconductor electronics to achieve robust high speed device at low cost. 2. Design of Wavelength Add–Drop Multiplexer In today’s fiber-optic networks, multiple wavelengths light propagate through single optical fiber. Each wavelength of light transmits its own information undisturbed by the other wavelengths. A single-channel wavelength add–drop multiplexer (WADM) is a device that can add or remove a specific wavelength of light from a fiber. Recently, more and more applications demand WADM that are capable of adding and removing multiple wavelengths. This section presents the design of multi wavelength add–drop multi- plexer which will add or drop multiple wavelength channels without affecting the other channels. The structure of the waveguide grating based add–drop multiplexer is shown in Fig. 1. It consists of two parallel identical single-mode cores, which are separated by a distance d and embedded in a rectangular cladding with thickness t and width w. Each core contains a periodic grating with length L, grating height h, and pitch . The cores have different grating profiles like rectangular, triangular and trapezoidal structures. The two gratings are placed in the light-propagation direction z. In this paper, the grating is treated as periodic perturbation to the waveguide structure. The pitch of the grating is so chosen that light is coupled between the guided mode of the  E-mail address: spmece@tce.edu OPTICAL REVIEW Vol. 18, No. 4 (2011) 305–310 305