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

Photonic-Crystal Fibers

A physiological sensor combination has a flexible substrate configured to attach to a tissue site. Multiple sensors are disposed on the substrate, which generate physiological signals. Each of the signals is responsive to a different physiological parameter. Conductors are carried on the substrate and routed between the sensors and at least one connector. The connector is configured to communicate the physiological signals to at least one monitor, which derives measurements of the parameters.

Physiological sensor combination

The literature describes more than 30 measurements, at wavelengths
between 249 and 1550 nm, of the absolute value of the nonlinear
refractive-index coefficient of fused silica. Results of these
experiments were assessed and best currently available values were
selected for the wavelengths of 351, 527, and 1053 nm. The best
values are (3.6 ± 0.64) × 10-16
cm2/W at 351 nm, (3.0 ± 0.35) ×
10-16 cm2/W at 527 nm, and (2.74 ±
0.17) × 10-16 cm2/W at 1053
nm.

Review and assessment of measured values of the nonlinear refractive-index coefficient of fused silica.

Bend resistant multimode optical fibers are disclosed herein. Multimode optical fibers disclosed herein comprise a core region and a cladding region surrounding and directly adjacent to the core region, the cladding region comprising a depressed-index annular portion comprising a depressed relative refractive index.

Bend resistant multimode optical fiber

A method for measuring the nonlinear refractive index of optical fibers with an error of less than 5% is demonstrated. The technique is based on measuring the nonlinear phase shift experienced by a dual-frequency beat signal, permitting a simple, highly sensitive, accurate, repeatable, and easily automated measurement procedure and sampling. Measurements of the nonlinear coefficient in standard telecommunication, dispersion-shifted, and a number of dispersion-compensated fibers are presented.

Direct continuous-wave measurement of n(2) in various types of telecommunication fiber at 1.55 microm.

The present invention relates to a dispersion-shifted fiber having a structure for effectively lowering polarization-mode dispersion. This dispersion-shifted fiber is a single-mode optical fiber mainly composed of silica glass and has a zero-dispersion wavelength set within the range of at least 1.4 µm but not longer than 1.7 µm. In particular, at least the whole core region of the dispersion-shifted fiber contains fluorine.

Dispersion-shifted fiber

Depolarized pump light is used in measurements of the nonlinear refractive index, n2, in optical fiber by the cross-phase-modulation method. High measurement repeatability within ±1% is obtained by this method. The nonlinear refractive index is determined for dispersion-shifted fiber, standard single-mode fiber, pure silica-core single-mode fiber, and dispersion-compensating fiber as 3.35 × 10−20, 2.96 × 10−20, 2.79 × 10−20, and 4.44 × 10−20 m2/W, respectively, at 1.55 μm. This shows that the nonlinear refractive indices of the optical fibers differ greatly according to glass composition.

Measurement of the nonlinear refractive index in optical fiber by the cross-phase-modulation method with depolarized pump light.

The temperature dependence of chromatic dispersion is examined for various types of fiber. Its coefficient is found to depend strongly on the dispersion slope. Dispersion-flattened fiber has a significantly low coefficient of -0.0005ps/nm/km/°C, compared with -0.0038ps/nm/km/°C for large-core nonzero dispersion-shifted fiber. Transmission lines with low dispersion slopes consisting of pure silica core fiber and dispersion-compensating fiber also exhibit low coefficients of less than -0.001ps/nm/km/°C because of their compensating effects.

Temperature dependence of chromatic dispersion in various types of optical fiber

The present invention relates to an optical fiber which enables favorable optical communications in 1.3-μm and 1.55-μm wavelength bands, and an optical transmission system including the same. The optical fiber according to the present invention has only one zero-dispersion wavelength within a wavelength range of 1.20 μm to 1.60 μm, the zero-dispersion wavelength existing within a wavelength range of 1.37 μm to 1.50 μm, and has a positive dispersion slope at the zero-dispersion wavelength, thereby enabling favorable optical communications utilizing each signal light in the 1.3-μm and 1.55-μm wavelength bands sandwiching the zero-dispersion wavelength.

Optical fiber and optical transmission system including the same

The dependence of the nonlinear refractive index n2 on glass compositions for optical fibers is clarified. The relation between n2 and germanium- or fluorine-doped SiO2 is calculated on the basis of the measurement of n2 at 1.55 μm with the improved cross-phase-modulation method, taking into account the radial distribution of the optical power in the fibers.

Takatoshi Kato

Papers

Dispersion-shifted fiber

Measurement of the nonlinear refractive index in optical fiber by the cross-phase-modulation method with depolarized pump light.

Temperature dependence of chromatic dispersion in various types of optical fiber

Optical fiber and optical transmission system including the same

Estimation of nonlinear refractive index in various silica-based glasses for optical fibers