A multichannel 2D photonic crystal fiber for gas detection

We show the possibility of identification of molecular gases with the help of a 2D photonic crystal fiber made of AR-Glass (Schott) and exhibiting waveguiding multichannel hollow cores fabricated by the stack and draw technology. The proposed approach consists of registration of specific features introduced by absorption of gas medium filling hollow channels on transmission spectra of the latter in the same spectral region. In the chosen working region between 5850 and 11 250 cm^?1, experimental transmission spectra of waveguiding channels of the sample fiber are similar in shape and represent curves with three characteristic peaks of transmission. Using model gaseous media as an example, we demonstrate the possibility of presenting the results of identification in the form of a multidigit binary code. The conditions for further development of the proposed approach are discussed.     

Analysis of one-dimensional Fibonacci-class quasicrystals using perturbation theory

In this work, we present a new and semi-analytical method to investigate one-dimensional Fibonacci-class photonic quasicrystals from waveguiding properties point of view. Usually, the exact treatment for obtaining band diagram in these situations is very hard and the numerical methods are used. In this paper, we investigate the waveguiding properties of one-dimensional quasicrystals by using perturbation method. In this direction, the band diagram and field distribution of this structure are investigated.     

Eigen electromagnetic waves of a coaxial waveguiding structure filled by a non‐uniform dissipative plasma with azimuthal magnetic field

This paper studies the propagation and spatial attenuation of high‐frequency eigen‐symmetric and dipolar electromagnetic waves along a coaxial plasma–metal waveguiding structure that contains a slightly axial and strong radial non‐uniform cylindrical plasma slab in an external azimuthal non‐uniform magnetic field. The influence of such parameters as the effective electron collision frequency, the direct current value producing the external azimuthal magnetic field, parameters that characterize plasma density radial profile, and waveguide geometric parameters on the dispersion, spatial attenuation, and radial field structure of the waves is considered. The regions of waveguiding structure parameters where the electromagnetic wave properties can be effectively controlled are studied and analyzed.     

Grating-mediated waveguiding

We propose a method of optical waveguiding, which relies on Bragg diffractions from a 1D grating that gives rise to waveguiding in the direction normal to the grating wave vector. The waveguide structure consists of a shallow 1D grating that has a bell- or trough-shaped amplitude in the confinement direction. Finally, we provide an experimental proof of the concept for this mechanism.     

Novel integrated optic intensity modulator based on mode coupling

Abstract

The analysis, design, realization, and measurements of a novel intensity modulator are reported. The operating principle is based on mode coupling between a passive low-loss SiON waveguide and an electro-optic high-loss polymer waveguiding structure. Matching the waveguides is critical and results in severe demands for the technology. Extended simulations by the Coupled Mode Theory, the Leaky Wave Model, and Finite Difference Beam Propagation Method resulted in the design of several modulator structures. After realization, modulation could be demonstrated at 632 nm and at 1523 nm using lossy waveguiding modes and surface plasmon modes.     

Novel integrated optic intensity modulator based on mode coupling

The analysis, design, realization, and measurements of a novel intensity modulator are reported. The operating principle is based on mode coupling between a passive low-loss SiON waveguide and an electro-optic high-loss polymer waveguiding structure. Matching the waveguides is critical and results in severe demands for the technology. Extended simulations by the Coupled Mode Theory, the Leaky Wave Model, and Finite Difference Beam Propagation Method resulted in the design of several modulator structures. After realization, modulation could be demonstrated at 632 nm and at 1523 nm using lossy waveguiding modes and surface plasmon modes.     

Mathematical simulation of nonlinear waveguiding systems based on 2D photonic crystals

A mathematical model of nonlinear two-dimensional waveguiding systems based on photonic crystals was constructed using the finite-difference time-domain method (FDTD), the total field/scattered field (TF/SF) method, and the perfectly matched layer method (PML). The constructed numerical algorithm can also be used for investigation of other two-dimensional waveguiding systems. The results of simulating the elements of particular waveguiding systems are presented.     

Ferroelectric SrxBa1-xNb2O6 optical waveguiding thin films on SiO2-coated Si(100) substrates

x Ba_1-xNb₂O₆ (x=0.5) films (abbreviated as SBN:0.5) on SiO₂-coated Si substrates are potential components for the application of integrated electro-optics devices. SBN:0.5 optical waveguiding thin films on SiO₂-coated Si substrates with a very thin MgO diffusion buffer have been successfully prepared by pulsed laser deposition. The as-grown films have a refractive index of 2.28, which is close to that of bulk SBN. X-ray analysis showed that the as-grown films have a single-phase tetragonal tungsten bronze structure. The SBN:0.5 thin films prepared by PLD exhibit favorable ferroelectric and optical waveguiding properties. The composition and the morphology of the films were also examined by XPS and by SEM, respectively. Ferroelectric SBN:0.5 optical waveguiding thin films on SiO₂-coated Si substrates are expected to be used in integrated electro-optic devices. Received: 27 February 1997/Accepted: 17 October 1997     

Advances in original fibres fabrication using innovative techniques

The development of original technologies to fabricate new kinds of fibres is presented here. First of all, the sol–gel process is developed to achieve fibres with original properties of waveguiding (new wavelength of emission of rare earths or transition metals, ultraviolet waveguiding): either a fibre composed of doped nanocrystals in a silica matrix or fibres composed of a one dimensional photonic bandgap structure. In this way, high refractive index dielectric oxides like ZrO₂, TiO₂ are studied. Secondly, the core suction technique associated with the stack and draw process is developed to fabricate fibres with various glasses and then, original profiles of refractive index to achieve multiwavelength lasers.     

Design of air-guiding honeycomb photonic bandgap fiber

We introduce a design procedure for hollow-core photonic bandgap (PBG) fiber with a cladding made of air-silica honeycomb photonic crystal (PC). It is found that air-guiding can be realized in both fundamental and secondary PBG regions of the cladding PC. Dispersion and radiation loss of the fundamental mode for two types of fiber structure are theoretically calculated. The fibers show promising waveguiding ability.     

Tapered photonic crystal fibres: properties, characterisation and applications

Microstructured optical fibres (MOFs) have attracted much interest in recent times, due to their unique waveguiding properties that are vastly different from those of conventional step-index fibres. Tapering of these MOFs promises to significantly extend and enhance their capabilities. In this paper, we review the fabrication and characterisation techniques of these fibre tapers, and explore their fundamental waveguiding properties and potential applications. We fabricate photonic crystal fibre tapers without collapsing the air-holes, and confirm this with a non-invasive probing technique that enables the characterisation of the internal microstructure along the taper. We then describe the fundamental property of such tapers associated with the leakage of the core mode that leads to long-wavelength loss, influencing the operational bandwidth of these tapers. We also revisit the waveguiding properties in another form of tapered MOF photonic wires, which transition through waveguiding regimes associated with how strongly the mode is isolated from the external environment. We explore these regimes as a potential basis for evanescent field sensing applications, in which we can take advantage of air-hole collapse as an extra dimension to these photonic wires.     

Numerical Study on the Waveguiding Properties of Photonic Crystal Fibers

The photonic band structure, mode field distribution, and leakage loss of different photonic crystal fibers are studied by the full vectorial plane wave expansion method and an extended beam propagation method. A comparison on the waveguiding mechanism is conducted among solid-core triangular-lattice PCF, air-core honeycomb PCF, and solid-core honeycomb PCF. For the latter two structures, which conduct light by the photonic bandgap effect, the advantages of down-doped solid-core honeycomb structure are demonstrated for its Gaussian-like mode field distribution and low leakage loss. A combined study on the leakage loss and band structure of solid-core honeycomb PCF has revealed the distinctive properties of photonic bandgap effect.     

Induced waveguiding in a two-dimensional Λ-configuration atomic medium

We show that induced waveguiding of a cw probe by a spatial soliton pump in a two-dimensional (one longitudinal and one transverse spatial dimension) Λ-configuration atomic medium can be achieved. The effects of probe-pump detuning and the initial probe transverse momentum on waveguiding are also examined.     

Complete modal decomposition for optical waveguides

Virtually all electromagnetic waveguiding structures support a multiplicity of modes. Nevertheless, to date, an experimental method for unique decomposition of the fields in terms of the component eigenmodes has not been realized. The fundamental problem is that all current attempts of modal decomposition do not yield phase information. Here we introduce a noninterferometric approach to achieve modal decomposition of the fields at the output of a general waveguiding structure. The technique utilizes a mapping of the two-dimensional field distribution onto the one-dimensional space of waveguide eigenmodes, together with a phase-retrieval algorithm to extract the amplitudes and phases of all the guided vectorial modes. Experimental validation is provided by using this approach to examine the interactions of 16 modes in a hollow-core photonic-band gap fiber.     

Temperature and pressure scaling of the alpha relaxation process in fragile glass formers: A dynamic light scattering study

We have experimentally observed the eigenmode splitting due to coupling of the evanescent defect modes in three-dimensional photonic crystals. The splitting was well explained with a theory based on the classical wave analog of the tight-binding (TB) formalism in solid state physics. The experimental results were used to extract the TB parameters. A new type of waveguiding in a photonic crystal was demonstrated experimentally. A complete transmission was achieved throughout the entire waveguiding band. We have also obtained the dispersion relation for the waveguiding band of the coupled periodic defects from the transmission-phase measurements and from the TB calculations.     

Ultraslow optical waveguiding in an atomic Bose-Einstein condensate

We investigate waveguiding of ultraslow light pulses in an atomic Bose-Einstein condensate. We show that under the conditions of off-resonant electromagnetically induced transparency, waveguiding with a few ultraslow modes can be realized. The number of modes that can be supported by the condensate can be controlled by means of experimentally accessible parameters. Propagation constants and the mode conditions are determined analytically using a Wentzel-Kramers-Brillouin analysis. Mode profiles are found numerically.     

Growth of optical waveguides by pulsed laser deposition

An overview of active and passive waveguiding thin films fabricated by pulsed laser deposition (PLD) is given. The focus is on materials used, deposition conditions, films characterization and on waveguiding properties. Parameters of lasing layers fabricated by PLD are summarized. Summary of potential applications of optical waveguides is presented.     

Ray-optics analysis of the coupling efficiency from a gaussian beam to a rectangular multimode embedded strip waveguide

The modified ray-optics method is used to analyze the coupling efficiency from a Gaussian beam to a rectangular multimode embedded strip waveguide. It is convenient for analyzing the case of a simple waveguide structure because of reduced computation time. The conditions for determining which optical rays can be coupled into the waveguide to become the waveguiding modes, as well as the effective receiving area of the waveguide, are derived in this work. The data obtained by this method are compared with those calculated by the well-known overlap integral theorem and Marcatili's models for investigating the validity of the modified ray-optics method.     

Rod type photonic crystal optical line defect waveguides with optical modulations

This paper reports the design and principles of two dimensional rod-type photonic crystal (PhC) line defect waveguides for bandgap based optical waveguiding, static modulation and high speed dynamic optical switchings. Experiments were carried out for both high aspect ratio and slab type configurations. The differences in waveguiding mechanisms for the two configurations resulting from the presence of bottom cladding systems, without out-of-plane symmetries are compared for their advantages and disadvantages. In particular, the designs of non-top-clad optical waveguides of layout sizes within micrometers and operational frequencies centered at the optical communication wavelength of 1550 nm, were investigated for the feasibility of large scale integration by batch fabrication process techniques – such as sub-micrometer optical lithography etc. Based on such techniques, specifically designed dispersions of line defect PhC waveguides within a missing row of PhC rods were accompanied by optical testing structures of suitable coupling modes. Optical measurements of waveguiding coefficients were therefore enabled for the different configurations, together with further static and dynamic modulations. PACS 42.70.Qs