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  2. Optical path length - Wikipedia

    en.wikipedia.org/wiki/Optical_path_length

    An electromagnetic wave propagating along a path C has the phase shift over C as if it was propagating a path in a vacuum, length of which, is equal to the optical path length of C. Thus, if a wave is traveling through several different media, then the optical path length of each medium can be added to find the total optical path length. The ...

  3. Electrical length - Wikipedia

    en.wikipedia.org/wiki/Electrical_length

    The electrical length of an antenna, like a transmission line, is its length in wavelengths of the current on the antenna at the operating frequency. [1] [12] [13] [4]: p.91–104 An antenna's resonant frequency, radiation pattern, and driving point impedance depend not on its physical length but on its electrical length. [14]

  4. Routing and wavelength assignment - Wikipedia

    en.wikipedia.org/wiki/Routing_and_wavelength...

    If resources along the fixed path are in use, future connection requests will be blocked even though other paths may exist. The SP-1 (Shortest Path, 1 Probe) algorithm is an example of a Fixed Path Routing solution. This algorithm calculates the shortest path using the number of optical routers as the cost function.

  5. Electromagnetic spectrum - Wikipedia

    en.wikipedia.org/wiki/Electromagnetic_spectrum

    The higher energy (shortest wavelength) ranges of UV (called "vacuum UV") are absorbed by nitrogen and, at longer wavelengths, by simple diatomic oxygen in the air. Most of the UV in the mid-range of energy is blocked by the ozone layer, which absorbs strongly in the important 200–315 nm range, the lower energy part of which is too long for ...

  6. Wavelength - Wikipedia

    en.wikipedia.org/wiki/Wavelength

    Wavelength is a characteristic of both traveling waves and standing waves, as well as other spatial wave patterns. [3] [4] The inverse of the wavelength is called the spatial frequency. Wavelength is commonly designated by the Greek letter lambda (λ). For a modulated wave, wavelength may refer to the carrier wavelength of the signal.

  7. Coherence length - Wikipedia

    en.wikipedia.org/wiki/Coherence_length

    Multimode helium–neon lasers have a typical coherence length on the order of centimeters, while the coherence length of longitudinally single-mode lasers can exceed 1 km. Semiconductor lasers can reach some 100 m, but small, inexpensive semiconductor lasers have shorter lengths, with one source [4] claiming 20 cm. Singlemode fiber lasers with linewidths of a few kHz can have coherence ...

  8. Fermat's principle - Wikipedia

    en.wikipedia.org/wiki/Fermat's_principle

    Fig. 1: Fermat's principle in the case of refraction of light at a flat surface between (say) air and water. Given an object-point A in the air, and an observation point B in the water, the refraction point P is that which minimizes the time taken by the light to travel the path APB.

  9. Path length - Wikipedia

    en.wikipedia.org/wiki/Path_length

    Optical path length, the product of the distance light travels and the refractive index of the medium it travels through; Mean free path, the average distance that a particle travels before scattering; Radiation length, a characteristic length for the decay of radiation in a medium