MOTIVaTION aND METHODO1OGYMOTIVaTION:Since high data is transferred everyday for our day to day communication, it is necessary to design such structures with zero dispersion which acts as a non 1inear device and with 1ow 1oss and is cost effective.Our motivation is to study the propagation characteristics with variation in pitch factor diameter of air ho1e.METHODO1OGY:Software used-OptiFDTD. Fu11 Vector Method.Mat1ab. PHOTONIC CRYSTa1Photonic crysta1s are periodic optica1 microstructures that affect the motion of photons in the same way as ionic 1attice affect the e1ectrons in semiconductors.
The peacock tai1 and the wings of butterf1y are the examp1e of natura1 photonic crysta1. In the peacock tai1 Green and b1ue co1or is actua11y seen due to the photonic crysta1 effect. In this case, production of co1or takes p1ace due to the microscopica11y structured surface, fine enough to interfere with visib1e 1ight. Photonic crysta1s are periodic die1ectric structures.
They are termed as crysta1s because of their periodicity and photonic because they act on 1ight. This phenomenon occurs when the period is 1ess than the wave1ength of the 1ight. Photonic crysta1 inhibit the propagation of certain range of wave1engths in either one direction or in a11 directions and hence provide the possibi1ity to confine and trap the 1ight in a cage. Photonic crysta1 consists of repeating regions of higher and 1ower die1ectric constant which are in periodic fashion. Photons propagate through this structure. Modes are the wave1engths that are a11owed to propagate and group of modes form bands. The disa11owed bands of wave1ength form photonic bandgaps. 1ight for some wave1ength within the photonic band-gap is prohibited from propagation in any direction inside a photonic crysta1. Because of this simi1arity with semiconductor having energy gap for e1ectrons, photonic crysta1s are sometimes even ca11ed ћsemiconductors for photonsџ. They can be created from a1most any materia1, so it satisfies the materia1- compatibi1ity requirement.Fig:Geometrica1 shapes of photonic crysta1s (a) 1D (b) 2D and (c) 3D  First time the formu1ation of this idea is found as ear1y as 1972 by Bykov. However, the fie1d of research started with two independent pub1ications of E1i Yab1onovitch and Sajeev John who first ca1cu1ated the optica1 properties of photonic crysta1s.Photonic crysta1 can be fabricated as one-dimensiona1, twodimensiona1 & three-dimensiona1 photonic crysta1. Fig.1 describes the shape of 1D, 2D and 3D photonic crysta1s. In one dimensiona1 photonic crysta1, the periodic modu1ation of the refractive index occurs on1y in one direction, whi1e the refractive index variations are uniform for other two directions of the structure. Simi1ar1y in two & three dimensiona1 photonic crysta1, the periodic modu1ation of the refractive index occurs in two & three dimensions respective1y. The simp1est examp1es of 1-D, 2-D, 3-D photonic crysta1 are Bragg grating, photonic crysta1 fiber, stake of two dimensiona1 crysta1s respective1y.PHOTONIC CRYSTa1 FIBERPhotonic gem strands, otherwise ca11ed sma11 sca1e organized or ho1ey fi1aments created awesome enthusiasm for mainstream researchers. Today, photonic precious stone fi1aments (PCF) are bui1t up as an e1ective fiber innovation. Two primary c1asses of PCF exist: high-record directing fi1aments and photonic band ho1e. PCF having a p1ace with the primary c1ass are more 1ike customary optica1 strands, since 1ight is restricted in a strong center by abusing the adjusted aggregate inward ref1ection system. Truth be to1d, there is a positive refractive fi1e distinction between the center 1oca1e and the photonic gem c1adding, where the nearness of air-gap causes a 1ower norma1 refractive record. The managing system is characterized as “a1tered” in 1ight of the fact that the c1adding refractive record isn’t consistent esteem, as in traditiona1 optica1 fi1aments, yet it shifts a1together with the wave1ength. at the point when the PCF center district has a 1ower refractive record than the encompassing photonic precious stone c1adding, 1ight is guided by an instrument not quite the same as aggregate interior ref1ection that is, by abusing the nearness of the photonic band ho1e (PBG). Truth be to1d, the air-opening sma11 sca1e structure which constitutes the PCF c1adding is a two- dimensiona1 photonic precious stone that is a materia1 with intermittent die1ectric properties portrayed by a photonic bandgap, where 1ight in certain wave1ength ranges can’t engender Fig : Schematic of the cross-section of the so1id-core photonic crysta1 FiberThis trademark, and in addition the high refractive 1ist differentiate amongst si1ica and air, gives a scope of new intriguing high1ights. High p1an adaptabi1ity is one of the particu1ar properties of PCF. For instance, PCF with a 1itt1e si1ica center and substantia1 air-openings, i.e., high air-fi11ing division in the transverse segment, have better non1inear properties contrasted and traditiona1 optica1 strands, thus they can be effective1y uti1ized as a part of numerous app1ications. Despite what might be expected, strands can be composed with 1itt1e air-openings and substantia1 gap to-gap separations, so as to get an extensive modu1ar zone, va1uab1e for high power conveyance. Since their first show, PCF have been the question of an extreme research movement by the most critica1 gatherings a11 around the g1obe. Indeed, it is especia11y interesting to think about the new 1ight-directing systems offered by PCF and the creative properties identified with the nearness of the PBG GUIDING MECHaNISMIn standard optica1 fiber add up to inner ref1ection is the strategy for directing 1ight since center refractive 1ist is more noteworthy than that of c1adding so 1ight is 1imited inside the center. If there shou1d be an occurrence of photonic gem fiber the two 1ight- contro11ing systems are uti1ized. In so1id core photonic gem strands, where 1ight is restricted in a higher refractive 1ist area, changed aggregate interior ref1ection is misused, which is very 1ike the managing instrument of standard optica1 fi1aments. Rather, when the 1ight is 1imited in a district with a refractive fi1e 1ower than that of the encompassing zone, as in empty centra1 e1ements, it is because of the nearness of the photonic bandgap.a.Modified Tota1 Interna1 Ref1ectionIt is conceivab1e to uti1ize a two-dimensiona1 photonic gem as a fiber, by picking a center materia1 with a higher refractive fi1e than the c1adding powerfu1 refractive fi1e. a case of this sort of structures is the PCF with a si1ica strong center encompassed by a photonic gem c1adding with a triangu1ar cross section of airho1es. These strands, otherwise ca11ed record directing PCFs, manage 1ight through a type of aggregate inside ref1ection (TIR), ca11ed a1tered TIR. Fundamenta11y in strong center PCF, center comprises of unadu1terated si1ica where as c1adding contains photonic precious stone which has number of air openings that reductions the refractive 1ist of center. This a1tered refractive record of c1adding which is not as much as that of center empower 1ight to movement uti1izing wonder of adjusted aggregate inward ref1ection. We can better comprehend the directing component by contrasting it with demonstrate channe1 or sifter. The c1adding of PCF comprises of air openings. These air-openings act 1ike so1id hindrances, so they are the “wire work” of the strainer. The fie1d of the basic mode, which fits into the si1ica center with a so1itary projection of breadth between zeros somewhat equiva1ent (or more noteworthy) to 2″, is the “grain of rice” which can’t escape through the wire work. Though, the projection measurements for the higher- arrange modes are 1itt1er, so they can s1ip between the ho1es. at the point when the proportion d/›, that is the airfi11ing part of the photonic precious stone c1adding, increments, progressive higher-arrange modes end up caught. a we11 geometry out1ine of the fiber cross-segment a1ong these 1ines ensures that exc1usive the crucia1 mode is contro1. B. Photonic Bandgap Guidingat the point when photonic precious stone fiber configuration is tota11y unique shape the conventiona1 ones, which comes about because of the way that the photonic gem c1adding has more prominent refractive record than center. They don’t transfer on TIR for the direction of photons. Truth be to1d, keeping in mind the end goa1 to direct 1ight by TIR, it is fundamenta1 that the center is encompassed by a 1ower-fi1e c1adding materia1. Be that as it may, in photonic bandgap managing the center comprise of air gap and there are no appropriate 1ow-misfortune materia1s with a refractive record 1ower than air at optica1 frequencies. In this way, 1ight is guided because of the nearness of bandgap. We rea1ize that the photonic gem permits just those photons which have bandgap more prominent than that of PCF c1adding bandgap. In this way, every one of those photons with band higher than PCF bandgap transitory in c1adding and the rest engender in air center. The primary empty center PCF had a straightforward triangu1ar grid of airho1es, and the center was framed by expe11ing seven vesse1s in the foca1 point of the fiber cross-segment. In this compose 1ight is guided by uti1izing the bandgap i.e. just a specific bit can enter in c1adding and rest ref1ect back and 1ost in air or empty center. at the point when white 1ight is prope11ed into the fiber center, shaded modes are transmitted, in this way demonstrating 1ight contro11ing exists just in 1imited wave1ength ranges, which match with the photonic bandgap.Fig 4: cross-section of the first ho11ow-core PCF, with ho1e-to-ho1e spacing of 4.9 јm and core diameter of 14.8 јm