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In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, or refracted, when entering a material. This is described by Snell's law of refraction, n1 sin θ1 = n2 sin θ2, where θ1 and θ2 are the angle of incidence and angle of refraction, respectively, of a ray crossing the interface between two media with refractive indices n1 and n2.
An optical fiber, or optical fibre in Commonwealth English, is a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair. Optical fibers are used most often as a means to transmit light between the two ends of the fiber and find wide usage in fiber-optic communications, where they permit transmission over longer distances and at higher bandwidths (data transfer rates) than electrical cables.
A fiber Bragg grating (FBG) is a type of distributed Bragg reflector constructed in a short segment of optical fiber that reflects particular wavelengths of light and transmits all others. This is achieved by creating a periodic variation in the refractive index of the fiber core, which generates a wavelength-specific dielectric mirror. Hence a fiber Bragg grating can be used as an inline optical fiber to block certain wavelengths, can be used for sensing applications, or it can be used as wavelength-specific reflector.
Fibers doped with bismuth show broad luminescence bands around 750, 1100, and 1400 nm with spectral bandwidths of 100 to 200 nm at room temperature. The luminescence bands can be observed by pumping b
2010
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Refractive index changes up to 2.5 × 10-3 were demonstrated in H2-loaded germanium free Bi-Al-doped silica fibers using both ArF excimer and cw-Ar+-244 nm lasers. Tensile stress changes indicate clear
The photosensitivity of germanium free Bi-Al-doped silica fibers with different bismuth concentrations was investigated using ArF excimer laser radiation at 193 nm and fiber grating formation. For the