Photonic crystals microstructures

In another approach, two cascaded microstructure-collapses on a photonic crystal fiber are intentionally introduced by C02 laser or electric arc heating31. In this way, the mismatch of core size along the fiber causes light coupling between the core and cladding modes. 

Metal-metal eutectics have been studied for many years due to their excellent mechanical properties. Recently, oxide-oxide eutectics were identified as materials with potential use in photonic crystals. For example, rodlike micrometer-scaled microstructures of terbium-scandium-aluminum garnet terbium-scandium per-ovskite eutectics have been solidified by the micro-pulling-down method (Pawlak et al., 2006). If the phases are etched away, a pseudohexagonally packed dielectric periodic array of pillars or periodic array of pseudohexagonally packed holes in the dielectric material is left. 

FIGURE 21.8 Scanning electron micrographs of several microstructured optical fibers including (a) high delta, (b) photonic crystal, (c) grapefruit, and (d) air-clad structures ... 

A photonic crystal-type stack of logs was obtained by TP initiated cross-linking radical polymerization of acrylates in the presence of poly(styrene-co-acrylonitrile) as binder and an amino substituted distyrylbenzene (58) as two-photon active initiator (Fig. 3.93) [133]. This photonic crystal-type microstructure has an average periodicity of 1 pm, a base area of 60 pm x 60 pm, and a height of 8 pm. The lines are about 200 nm wide, which is considerably smaller than the fabrication wavelength (Fig. 3.93) [133]. 

Fig. 2 Various types of hollow-core photonic bandgap fibers, (a) Photonic crystal fiber featuring small hollow core surrounded by a periodic array of large air holes, (b) Microstructured fiber featuring medium-sized hollow core surrounded by several rings of small air holes separated by nano-size bridges, (c) Bragg fiber featuring large hollow core surrounded by a periodic sequence of high and low refractive index layers...

Cordeiro CMB, de Matos CJS, dos Santos EM, Bozolan A, Ong JSK, Facincani T, Chesini G, Vaz AR, Brito Cruz CH (2007) Towards practical liquid and gas sensing with photonic crystal fibres side access to the fibre microstructure and single-mode liquid-core fibre. Meas Sci Technol 18 3075-3081... 

Alexeev VL, Das S, Finegold DN, Asher SA (2004) Photonic crystal glucose-sensing material for noninvasive monitoring of glucose in tear fluid. Clin Chem 50(12) 2353-2360 Allcock HR, Phelps MVB, Barrett EW, Pishko MV, Koh WG (2006) Ultraviolet photolithographic development of polyphosphazene hydrogel microstructures for potential use in microarray biosensors. Chem Mater 18(3) 609-613... 

A major limitation of the sensitivity of this type of sensor is the ability to transfer optical power into the evanescent field. Recent work has incorporated new types of fibers to increase the sensitivity of measurements. Newly developed hollow core fibers, which guide light mainly in the cladding, can be used to couple more power into the sensitive materials [76]. If the hollow core fiber is used as the active sensing area between two silica core fibers, then the transitions between the fibers will force the light to travel from the core into the cladding then back into the core. Another type of fiber is the microstructure fiber or photonic crystal fiber, which incorporates air holes into... 

In many applications, the polarization state of gnided light can be fixed in a particular direction and only the passive optical guiding characteristics of a PBG material come into play. Two-dimensional (2D) periodic microstructures are often sufficient for such applications. For 2D periodic dielectrics, advanced planar microstructuring techniques borrowed from semiconductor technology can greatly simplify the fabrication process. Such structures are referred to as photonic crystals exhibiting a 2D PBG. The aspect ratio of a 2D PBG material is defined as the ratio of the sample depth (vertical direction) to the lattice constant (transverse direction). 

Bengtsson M, Ekstrom S, Drott J, Collins A, Csoregi E, Marko-Varga G, Laurell T (2000) Applications of microstructured porous silicon as a biocatalytic surface. Phys Stat Sol 182 495-504 Bimer A, Li A-P, Muller F, Gdsele U, Kramper P, Sandoghdar V, Mlynek J, Busch K, Lehmann V (2000) Transmission of a microcavity structure in a two-dimensional photonic crystal based on macroporous silicon. Mat Sci Semicon Proc 3 487-491 Carstensen J, Christophersen M, Foil H (2000) Pore formation mechanisms for the Si-HF system. Mat Sci Eng B 69/70 23-28... 

Fini JM (2004) Microstructure fibres for optical sensing in gases and liquids. Meas Sd Technol 15 1120-1128 Frazao O, Santos JL, Araujo EM, Ferreira LA (2008) Optical sensing with photonic crystal fibers. Laser Photon Rev 2(6) 449- 59... 

Luminescence differs from chromic effect in that luminescence is not a colour change but emits light. Opticoluminescence is a typical effect encountered in optical fibres. Opticoluminescent fibres have been widely used in textiles for the function of accurately monitoring body and environmental conditions. Recently photonic crystal fibres (PCFs) have been introduced. The cross-section of the PCF contains either periodically arranged micron-scale air voids or a periodic sequence of micron-scale layers of different materials. " PCFs can appear coloured due to optical interference effects in the microstructured regions. 

Figure 7.10 Microstructures fabricated byTPP for various applications, (a) 3D photonic crystal with woodpile-like configuration (reproduced with permission from [79], Copyright (2004) Nature Publishing Group (b) Optically attenuated nanotweezers (reproduced with permission from [104], Copyright (2003) American Institute of Physics) (c) A microinductor (reproduced with permission from [15], Copyright (2007) Elsevier Limited) and (d) a 3D scaffold for studying cells motility...

Straub, M., Nguyen, L.H., Fazhc, A., and Gu, M. (2004) Complex-shaped three-dimensional microstructures and photonic crystals generated in a polysiloxane polymer by two-photon microstereolithography. Opt. Mater.,... 

Fu, Y., Willander, M., Ivchenko, E. L. (2000). Photonic dispersions of semiconductor-quantum-dot-array-based photonic crystals in primitive and face-centered cubic lattices. Superlattices and Microstructures, 27, 255-264. 

Candiani A, Margulis W, Sterner C, Konstantaki M, Pissadakis S (2011) Phase-shifted Bragg microstructured optical fiber gratings utilizing infiltrated ferrofluids. Opt Lett 36 2548-2550 Cao WY, Munoz A, Palffy-Muhoray P, Taheri B (2002) Lasing in a three-dimensional photonic crystal of the liquid crystal blue phase II. Nat Mater 1 111-113... 

Ballato, J., Tailorable visible photonic bandgaps through microstructural order and coupled material effects in SiOj colloidal crystals, J. Opt. Soc. Am. B, 17, 219, 2000. 

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