J.P. de Sandro

Bio: J.P. de Sandro is an academic researcher from University of Southampton. The author has contributed to research in topics: Optical fiber & Fiber Bragg grating. The author has an hindex of 12, co-authored 19 publications receiving 1479 citations.

Large mode area photonic crystal fibre

Abstract: The authors report the realisation of a new design for a large mode area monomode optical fibre. This photonic crystal fibre will guide only a single mode, no matter how large the fibre diameter, provided the shape is kept constant. This is demonstrated with a fibre which has a core diameter equal to approximately 50 free-space wavelengths.

Properties of photonic crystal fiber and the effective index model

Abstract: We report on the waveguiding properties of a new type of low-loss optical waveguide. The photonic crystal fiber can be engineered to support only the fundamental guided mode at every wavelength within the transparency window of silica. Experimentally, a robust single mode has been observed over a wavelength range from 337nm to beyond 1550nm (restricted only by available wavelength sources). By studying the number of guided modes for fibers with different parameters and the use of an effective index model we are able to quantify the requirements for monomode operation. The requirements are independent of the scale of the fiber for sufficiently short wavelengths. Further support for the predictions of the effective index model is given by the variation of the spot size with wavelength,

Greater than 20%-efficient frequency doubling of 1532-nm nanosecond pulses in quasi-phase-matched germanosilicate optical fibers.

Abstract: We fabricated second-order nonlinear gratings in D-shaped germanosilicate fibers, using thermal poling and periodic electrodes defined by standard photolithography. These gratings, which are up to 75??mm long, were used for efficient quasi-phase-matched frequency doubling of 1.532??m nanosecond pulses from a high-power erbium-doped fiber amplifier. Average second-harmonic powers as high as 6.8??mW and peak powers greater than 1.2??kW at 766??nm were generated, with average and peak conversion efficiencies as high as 21% and 30%, respectively.

High-performance optical fiber polarizers based on long-period gratings in birefringent optical fibers

Abstract: We have demonstrated the feasibility of achieving high-performance fiber polarizers (insertion loss 30 dB), based on polarization mode dispersion in a long-period grating. Chirped operation with 100-nm bandwidth has also been achieved, showing the possibility of a broad-band device.

Photonic crystal fibers

Abstract: Photonic crystal fibers guide light by corralling it within a periodic array of microscopic air holes that run along the entire fiber length Largely through their ability to overcome the limitations of conventional fiber optics—for example, by permitting low-loss guidance of light in a hollow core—these fibers are proving to have a multitude of important technological and scientific applications spanning many disciplines The result has been a renaissance of interest in optical fibers and their uses

Photonic-Crystal Fibers

Abstract: The history, fabrication, theory, numerical modeling, optical properties, guidance mechanisms, and applications of photonic-crystal fibers are reviewed

Photonic crystal fibres

Abstract: A photonic crystal fibre including a plurality of longitudinal holes (220), in which at least some of the holes have a different cross-sectional area in a first region (200) of the fibre, that region having been heat-treated after fabrication of the fibre, from their cross-sectional area in a second region of the fibre (190), wherein the optical properties of the fibre in the heat-treated region (200) are altered by virture of the change in cross-sectional area of holes (230) in that region (200).

Photonic Band Gap Guidance in Optical Fibers

Abstract: A fundamentally different type of optical waveguide structure is demonstrated, in which light is confined to the vicinity of a low-index region by a two-dimensional photonic band gap crystal. The waveguide consists of an extra air hole in an otherwise regular honeycomb pattern of holes running down the length of a fine silica glass fiber. Optical fibers based on this waveguide mechanism support guided modes with extraordinary properties.

Fiber Bragg gratings

Abstract: Since the discovery of photosensitivity in optical fibers there has been great interest in the fabrication of Bragg gratings within the core of a fiber. The ability to inscribe intracore Bragg gratings in these photosensitive fibers has revolutionized the field of telecommunications and optical fiber based sensor technology. Over the last few years, the number of researchers investigating fundamental, as well as application aspects of these gratings has increased dramatically. This article reviews the technology of Bragg gratings in optical fibers. It introduces the phenomenon of photosensitivity in optical fibers, examines the properties of Bragg gratings, and presents some of the important developments in devices and applications. The most common fabrication techniques (interferometric, phase mask, and point by point) are examined in detail with reference to the advantages and the disadvantages in utilizing them for inscribing Bragg gratings. Reflectivity, bandwidth, temperature, and strain sensitivity of the Bragg reflectors are examined and novel and special Bragg grating structures such as chirped gratings, blazed gratings, phase-shifted gratings, and superimposed multiple gratings are discussed. A formalism for calculating the spectral response of Bragg grating structures is described. Finally, devices and applications for telecommunication and fiber-optic sensors are described, and the impact of this technology on the future of the above areas is discussed.