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The Voigt profile is normalized: (;,) =,since it is a convolution of normalized profiles. The Lorentzian profile has no moments (other than the zeroth), and so the moment-generating function for the Cauchy distribution is not defined.
The presence of other molecules close to the molecule involved affects both line width and line position. It is the dominant process for liquids and solids. An extreme example of this effect is the influence of hydrogen bonding on the spectra of protic liquids. Observed spectral line shape and line width are also affected by instrumental factors.
Laser linewidth is the spectral linewidth of a laser beam. Two of the most distinctive characteristics of laser emission are spatial coherence and spectral coherence . While spatial coherence is related to the beam divergence of the laser, spectral coherence is evaluated by measuring the linewidth of laser radiation.
Full width at half maximum. In a distribution, full width at half maximum (FWHM) is the difference between the two values of the independent variable at which the dependent variable is equal to half of its maximum value.
The concept of a linewidth is borrowed from laser spectroscopy. The linewidth of a laser is a measure of its phase noise. The spectrogram of a laser is produced by passing its light through a prism. The spectrogram of the output of a pure noise-free laser will consist of a single infinitely thin line.
Since the linewidth and the free spectral range are independent of frequency, whereas in wavelength space the linewidth cannot be properly defined and the free spectral range depends on wavelength, and since the resonance frequencies scale proportional to frequency, the spectral response of a Fabry–Pérot resonator is naturally analyzed and ...
The remote receiver geometry is uncommon because generating a local oscillator signal that is coherent with a signal of independent origin is technologically difficult at optical frequencies. However, lasers of sufficiently narrow linewidth to allow the signal and LO to originate from different lasers do exist. [6]
The 1/e 2 width is equal to the distance between the two points on the marginal distribution that are 1/e 2 = 0.135 times the maximum value. In many cases, it makes more sense to take the distance between points where the intensity falls to 1/e 2 = 0.135 times the maximum value.