Low loss 2-port OADM using 1-D Photonic Crystal and 3-Port Optical Circulator Renilkumar M, 1,* and Prita Nair 1 1 Dept. of Physics, SSN College of Engineering, Chennai, Tamilnadu, India, 603110 *Corresponding author: renilkumarm@ssn.edu.in Abstract The simple architecture of a 2-port optical add drop multiplexer (OADM) using a 1-D photonic crystal (PC) filter and a 3-port optical circulator is presented. A low insertion loss of less than 2dB for express channels and 7dB for a drop channel is demonstrated using a superluminescent diode laser and an optical spectrum analyzer in the 1450nm-1650nm wavelength range. The channel isolation is 18dB. The main component of the OADM is the photo- nic crystal filter which is realized by a simple and low cost wet aniso- tropic etching of <110> oriented silicon. The pass band width of the drop channel at a peak wavelength of 1557nm is less than 7nm and a thermally induced wavelength drift of 0.04nm/K is experimentally measured. Therefore, this low cost solution is best suited for metro CWDM networks, where the channel spacing is 20nm. 1. Introduction The ever increasing demands for bandwidth hogging applications like residential triple play services and high speed Internet have pushed the telecommunication industries to introduce wavelength division multiplexing (WDM) technology in the metro access network. In such a network, it is necessary to insert, remove or bypass traffic at certain network nodes for low latency dynamic provisioning of services. The network element which performs this task is known as Optical Add-drop Multiplexers (OADMs), Eldada et al [2006] and Sayeed et al [2007]. Apart from add-drop or bypass functionality, OADMs enable a flexible network by dynamically providing gain/ power control, remote monitoring and configuration management. Two main types of OADMs deployed in the current metro access WDM networks are fixed OADMs and reconfigurable OADMs (ROADMs). Fixed OADMs operate on dedicated WDM channels while ROADMs enable a fully automated intelligent network by providing remote reconfiguration of WDM channels. Different technologies such as all fiber, Nykolak et al [1997], planar light wave circuit (PLC), Hattori et al [1998], and free space optics, Chiou et al [2001], are used for OADM architectures. These technologies have either high insertion loss or high cost which prevents their excessive deployment in metro and access networks where the major requirement is for devices with low capital outlay and low operational expenses. A two-channel CWDM OADM has been reported by Paulo T. Neves Jr. et al [2006], which uses two large band width fiber Bragg gratings (FBG), two circulators and two optical switches. They reported a high insertion loss of 12dB for express channels and 4dB for drop channels. A channel switching add/drop multiplexer with a tunable FBG has been reported by Feng et al, [2000]. It uses two 3dB couplers and reported high insertion loss. In this paper, we report the architecture of a low loss fixed OADM using a 1- D PC filter and a 3-port circulator. The 1-D PC with a central planar defect layer realized by the wet anisotropic etching of (110) silicon acts as INSTITUTE OF SMART STRUCTURES AND SYSTEMS (ISSS) JOURNAL OF ISSS J. ISSS Vol. 1 No. 1, pp. 10-15, Sept 2012. REGULAR PAPER Available online at www.isssonline.in/journal/01paper02.pdf Paper presented at ISSS International Conference on Smart Materials Structures & Systems, January 4-7, 2012, (ISSS 2012) Bangalore, India 10 Keywords: Optical add drop multiplexer, Photonic crystal filter, Wavelength division multiplexing