Volume 2 • Issue 1 • 1000114 J Laser Opt Photonics ISSN: 2469-410X JLOP, an open access journal Open Access Research Article Tripathy et al., J Laser Opt Photonics 2015, 2:1 DOI: 10.4172/2469-410X.1000114 Journal of Lasers, Optics & Photonics J o u r n a l o f L a s e r s , O p t i c s & P h o t o n i c s ISSN: 2469-410X Nonlinear Rectangular Photonic Crystal Fiber (PCF) for Optical Communication Exclusively Super Continuum Generation Tripathy SK 1 *, Achary JSN 2 , Muduli N 3 and Palai G 4 1 NIST Berhampur, Odisha, India 2 Ganjam College, Ganjam, Odisha, India 3 GEC Bhubaneswar, Odisha, India 4 GITA Bhubaneswar, Odisha, India *Corresponding author: Tripathy SK, NIST Berhampur Odisha, India, Tel: +91-680- 2492421/22; E-mail: Sukant_@uml.edu Received November 24, 2014; Accepted January 16, 2015; Published January 30, 2015 Citation: Tripathy SK, Achary JSN, Muduli N, Palai G (2015) Nonlinear Rectangular Photonic Crystal Fiber (PCF) for Optical Communication Exclusively Super Continuum Generation. J Laser Opt Photonics 2: 114. doi:10.4172/2469-410X.1000114 Copyright: © 2015 Tripathy SK, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Keywords: PCF; FDTD method; Kerr nonlinearity; Super- continuum generation Introduction Photonic crystal fbers also known as micro structured optical fbers have become a major topic of research over the last decade [1,2]. Te kinds of fbers are fabricated mainly by a single material (glass or polymer). Te cross-section of the fber consists of a core area surrounded by a periodic array of holes, and air holes running along the length of the fber, where the light can be either guided based on index- or band gap guidance mechanism depending on the refractive index contrast between the core and the cladding [3-5]. A holey cladding in PCFs control the nonlinear coefcient and dispersion property [6] in such way that, the conventional fber does not do this. Such PCFs can control the chromatic dispersion keeping high nonlinear coefcient, which is most important application for nonlinear optics. Now a day, the highly nonlinear PCF is commonly used type. Teir use are wide feld of applications ranges from spectroscopy and sensor [7,8] to direct telecom. Te high nonlinear coefcient and designable dispersion properties make these fbers attractive for many nonlinear applications of which super continuum(SC) generation has been the most intensively investigated and this has been used in application like optical coherence tomography, spectroscopy, metrology [9-11]. In a telecommunication era, the spectral slicing of broadband SC spectra has also been proposed as a simple way to create multiwave length optical sources for dense wavelength division multiplexing applications [12,13]. High nonlinear PCFs are good approach and used to generate super continuum generation pumped by ultrafast laser pulses and longer laser pulses, however super continuum generation in PCFs is restricted by dispersion properties. Mode feld area of PCF is the key factor to generate the nonlinear coefcient i.e. as small as the mode feld area, the increase in the nonlinear coefcient which leads to super continuum generation. Our research is aimed to design the rectangular PCF by adjusting suitable cladding variables to determine the high nonlinear coefcient and some dispersion properties. An interesting conclusion found from our simulation is that, the proposed rectangular PCF structure has slightly more nonlinear coefcient as compared to the highly nonlinear silica hexagonal photonic crystal fber at a wavelength 1.55 µm with same efective mode area [14]. So our proposed rectangular PCF is a suitable candidate for application like super continuum generation and nonlinear fber optics. Structural Design We propose to design a rectangular PCF of complex confguration with diferent circular air holes, which arranged in regular pattern. Te nonlinearity and dispersion can be controlled by air hole diameter as well as pitch values. Te PCF structure is in the form of inner cladding with small air hole and outer cladding with large air hole rectangular distribution as shown in Figure 1. Considering d 1 , Ʌ 1 are the air hole diameter and the pitch of the inner cladding, while d 2 , ∆ 2 are the air hole diameter and pitch of outer cladding respectively. Te hole to hole spacing (Ʌ) can be chosen to minimize the value of efective mode area, however it is not always desirable to use the structure with smaller efective mode area because it exhibits high confnement loss. In addition by adding more ring of air hole to fber cladding, it is possible to reduce confnement loss. Cladding region can be mostly comprised of air hole, Basically PCFs with small scale cladding feature and large air flling fraction (large value of d/Ʌ) light can be confned extremely tightly with in the core, resulting in small mode feld area and large value of nonlinear coefcient (γ). Te nonlinear coefcient of PCFs is tailored by changing the air flling rate of the cladding, while chromatic dispersion property can be obtained by varying air hole diameter and the pitch value. It is very difcult to obtain both high nonlinear coefcient and chromatic dispersion, if PCFs with same air Abstract A rectangular PCF structure in BK7 glass with inner and outer cladding is used to investigate effective mode feld area, high nonlinear coeffcient, and confnement loss and dispersion property using 2D FDTD technique. The PCF structure is purposed to design with pitches and air hole diameter in a periodic array fashion. The different properties of PCF structure like mode feld area, nonlinear coeffcient, confnement loss and dispersion are to be analyzed. The variation is investigated with change of different parameters like Ʌ 1 1 1 d Λ , 2 1 Λ Λ , and d1/d2 for a wide range of wavelength. The proposed rectangular PCF structure has slightly more nonlinear coeffcient (γ=36.98 W -1 km -1 ) than the highly nonlinear silica photonic crystal fber (γ=35 W -1 km -1 ) at a wavelength of 1.55 µm with almost same mode feld area (A eff ~ 2.8 µm 2 ). This result seems to be important in super-continuum generation and nonlinear fber optics.