Photonic Crystal Fibers(1) Optical Properties

Photonic Crystal Fibers(1) Optical Properties M.FujitaM.TanakaS.Yamadori A.Suzuki S.Koyanagi T.Yamamoto Summary The cladding of Photonic Crystal Fiber (PCF) is constituted of air holes arranged as periodically as the wavelength of light in the silica glass. The cladding having a structure made up of silica glass and air holes enables characteristics that are quite different from those of conventional fibers. In this paper, we introduce the outline of fabrication and structure of PCF and explain dominant optical properties of PCF compared with those of conventional step index fibers. Key wordsoptical fiber, Photonic crystal fiber, Singlemode fiber, Fiber characterization TIRTotal Internal Reflection PBGPhotonic Band Gap PCF : Photonic Crystal Fiber 2 1995Russel 1996 PBG PBG PCF PBG1997Honeycomb Lattice PBG

99 22 1998 Triangular Lattice PBGPCF PBG PCF PCF PCF a b PCF PCFPBG Fig. 1 PCF PCF Fig. 2 c d Examples of photonic crystal fibers aindex guiding PCF bairclad fiber choleassisted fiber dpbf apcfb cdpbf Fig. 1 SEM photograph of PCF PCF HF : Holey Fiber MicroStructured Fiber PCF Fig. 2 PBG PCFPBFPBGF Fig. 2d PCFIndex Guiding PCF PCF Fig. 2a Fig. 2b Ge Fig. 2c Holey Fiber Holeassisted PCF Table 1 TriangularHoneycomb Fig. 3ab Single Defect

Table 1 Structure of PCF PCF Triangular) Honeycomb) PCF Stack Draw StackDraw Fig. 4PCF Fig. 3 Crosssectional view of photonic crystal fibers atriangular structure bhoneycomb structure ab Defect PCF Fig. 3a PCF Λ d2a d/λ Λ A i r Filling FractionF Λ/λ Λ 2a 2Λ Fig. 4 Fabrication process of PCF PCF PCF PCF PCF ESMEndlesslySingle Mode xy

99 22 PCF PCF PCF ESM ESM b k 2p/l neff=b/k d/l=.6nefffig. 5 l d/l=.6l/l 1.5 d/l d/l.4 ESM V λ V 2.4 PCF Λnoneff neff Fig. 5 Veff Fig. 6 Veff Λ/λ Fig. 6 eff versus Λ/λ eff Λ/λ Fig. 5 Effective cladding index and modal index d/λ.6 Fig. 5 l l d/l Veff Veff PCF 4.1 d/l.4 Fig. 7 PCF d/l=.45 ESMV V V 2.4 a:λnconcl nconcl aλ=155nm bλ=532nm Fig.7 Near field pattern of PCF d/λ.45

532nm 155nm Fig. 8 PCF 532nm Table 2 Mode field diameter d/λ.6 PCF SMF.85 1.31 1.55 9.59 9.76 9.57 8.44 8.94 9.2 MM 9.21 1.23 µmsmf MM n NA PCF neff nco NA Fig. 9 PCF NA Fig. 8 Far field pattern at λ=532nm 532nmd/Λ.45 PCF NA V w Fig. 9 Far field pattern when illuminated with a whitelight source a: V PCF V d/λ=.6 Table 2 1.3µm NA NA OH PCF PCF Fig.1 Fig.11 1/λ 4 Λ 7.3µmd 4.2µm.47dB/km@1.55µm.5dB/km A=1.2 B=.25 A

99 22 Fig. 1 Loss spectrum Λ7.3µmd4.2µ Fig. 11 1/λ 4 plot 1/λ 4 B OH PCF PCF Confinement Loss PCF W d/λ Λ=2.3µm Fig.12 d/λ PCF Fig. 12 Confinement loss as a function of wavelength Λ 2.3µm 3 PCF PCF Fig.13 d/λ d/λ Fig. 13 Bending loss properties Λ2.3µm Fig.13 Λ=2.3µm d/λ.35 PCF Table 3 Λ 2.1µmd 1.1µmd/Λ

.52 PCF Table 3 Bending loss Λ2.1µmd/Λ.5 db/m mm µm 1.31 SMF.12 DSF.4 DCF PCF 2 1.55 1.62 6.69 18.23.2.81.4 1.31 7.37 1 1.55 1.62 1.18 22.4 1.31.21 5 1.55 1.62 1.31 3 1.55 1.62 Fig.13 dλ d Λ Λ/2 PCF Ge 1.27µm 1.27µm PCF Ge 1.27µm PCF Λ=2.3µm d/λ Fig.14 d/λ d/λ Fig. 14 Group velocity dispersion GVD Λ 2.3µm PCF 1.27µmFig.14d/Λ=.45.8µm PCF1µm (21) PANDAPolarizationmaintaining AND Absorptionreducing PCF (22) Fig.15 PCF

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