Abstract—A compact 1x3 power splitter based on Photonic Crystal Waveguides (PCW) with flexible power splitting ratio is presented in this paper. Multimode interference coupler (MMI) is integrated with PCW. The device size reduction compared with the conventional MMI power splitter is attributed to the large dispersion of the PCW. Band Solve tool is used to calculate the band structure of PCW. Finite Difference Time Domain (FDTD) method is adopted to simulate the relevant structure at 1550nm wavelength. The device is polarization insensitive and allows the control of output (o/p) powers within certain percentage points for both polarizations. Keywords—Dispersion, MMI Coupler, Photonic Bandgap, Power Splitter. I. INTRODUCTION OWER splitting is the basic function of the integrated optics. Such devices play vital role in passive optical distribution network, complex photonic integrated circuits as well as advanced active components such as interferometer, switches [1],[2] and nonlinear all optical devices[3],[4]. In the last few decades various solutions have proposed to split and combine optical signal. MMI coupler based power splitters are popular due their compact structure, polarization insensitivity and tolerance to fabrication parameter[5]. By using conventional rectangular geometry of MMI coupler only discrete power splitting ratio can be obtained even when the overlapping of the self images is introduced [6]. For several applications free choice of power splitting is adventages.In optical networks when “tap” function is required a small portion of the power is required depending on the situation. Ring lasers with 2x2 MMI couplers at its o/p were proposed to obtain a flexible power splitting ratio [7]. The device is complex. In [8] a new class of MMI coupler with interference section in between to have a free choice of power splitting ratio is proposed. Later a concept of tapering in MMI coupler was investigated. [9]. In [10] MMI coupler with tunable power splitting ratio is realized.Such devices have wide tuning range, compact structure and find applications in optical switches.These devices offer around 20% tunability. In 1991, the idea that the well known “stop bands” in periodic structure could be extended to prevent propagation in all the directions was leading to attempts worldwide, to Jyothi Digge is with SGB Amravati University, India (+91 9820207508; fax: 303-555- e-mail: jyothijayarajdigge@rediffmail.com). B. U. Rindhe is with SGB Amravati University, India (e-mail- burindhe@yahoo.com). S. K. Narayankhedkar is with MGM College of Engineering and Technology, Mumbai, India (e-mail: skniitb@yahoo.com). fabricate three-dimensional PBG materials. Hence photonic crystal fibers (PCF), which guides the light by PBG effect, were fabricated. [11]. Since then several PCF based devices such as lasers, filters, switches and multiplexers and demultiplexers were realized. The concept of multicore PCF lead to the realization of 1x4, 1x8 power splitters with fixed power splitting ratio [12],[13]. This concept of multicore in PCF was extended to design the 1x4 PCF with flexible splitting ratio by modifying the core diameter [14].With the development of PCWs, several PCW based devices such as interoferometers, lasers, multiplexers, demultiplexers and power splitters were developed. Current research is to integrate MMI coupler with PCW, which allows the realization of true time delay line(TTD)[15] and other photonic devices. In this paper, we have integrated MMI coupler and PCW array to design and analyze 1x3 power splitter with flexible power splitting ratio. The light enters the MMI coupler and diverges, finally enters the three PCWs. The amount of power coupled to the o/p waveguides depends on the width and effective index of the waveguide. The power coupled to the o/p waveguide is controlled by varying the d/a ratio of the dielectric rods. Where “d” is the diameter of the rod and parameter “a” represents the periodicity of the lattice. This paper is separated into 4 sections. Section II explains the design and analysis. Section III describes the simulation results. Finally section IV provides some conclusion. II. DESIGN AND ANALYSIS The proposed 1x3 power splitter is schematically depicted in Fig. 1. The width of the i/p waveguide (b)=1μm which is a single mode waveguide. MMI coupler is a slab waveguide with refractive index n=3.45. The dimension of the MMI coupler is 15x15μm.MMI coupler is integrated with PCW array.PCW array is rectangular lattice of dielectric rods in air. The radius, and the refractive index of the rods are taken r=0.2a, and n=3.45.The three PC (Photonic Crystal) waveguides are created by eliminating three rows rods. (Creating line defect in PC) and the diameter of the rods adjacent to the waveguides are varied as a/λ,a/2λ and a/3λ where λ is the operating wavelength (creating point defect in PC). The thickness of the guiding layer is 150nm.Substrate thickness is 500nm. These o/p PC waveguides are replacing the conventional waveguides. This arrangement is shown in Fig. 2. Jyothi Digge, B. U. Rindhe, and S. K. Narayankhedkar Photonic Crystal Waveguide 1x3 Flexible Power Splitter for Optical Network P World Academy of Science, Engineering and Technology International Journal of Physical and Mathematical Sciences Vol:7, No:1, 2013 138 International Scholarly and Scientific Research & Innovation 7(1) 2013 scholar.waset.org/1307-6892/8788 International Science Index, Physical and Mathematical Sciences Vol:7, No:1, 2013 waset.org/Publication/8788