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  2. Quasi-phase-matching - Wikipedia

    en.wikipedia.org/wiki/Quasi-phase-matching

    This allows quasi-phase-matching to exist at different domain widths . From this equation it is apparent, however, that as the quasi-phase match order increases, the efficiency decreases by . For example, for 3rd order quasi-phase matching only a third of the crystal is effectively used for the generation of signal frequency, as a consequence ...

  3. Nonlinear optics - Wikipedia

    en.wikipedia.org/wiki/Nonlinear_optics

    Quasi-phase-matching can be expanded to chirped gratings to get more bandwidth and to shape an SHG pulse like it is done in a dazzler. SHG of a pump and self-phase modulation (emulated by second-order processes) of the signal and an optical parametric amplifier can be integrated monolithically.

  4. Periodic poling - Wikipedia

    en.wikipedia.org/wiki/Periodic_poling

    The structure is designed to achieve quasi-phase-matching (QPM) in the material. Periodically poled crystals are frequently used as nonlinear optical materials. They are more efficient at second-harmonic generation than crystals of the same material without periodic structure.

  5. Second-harmonic generation - Wikipedia

    en.wikipedia.org/wiki/Second-harmonic_generation

    Diagram of second-harmonic generation with perfect phase matching =. Diagram of second-harmonic generation with an imperfect phase matching . In this case energy flows forth and back from the pump to the frequency doubled signal, and having a thick crystal can lead to a smaller amount of SHG produced.

  6. QPM - Wikipedia

    en.wikipedia.org/wiki/QPM

    Quantitative phase contrast microscopy, a group of microscopy methods; Quasi-phase-matching, a technique in nonlinear optics; Queen's Police Medal, awarded to UK/Commonwealth police officers; Questions of Procedure for Ministers, the confidential predecessor of the Ministerial Code (United Kingdom)

  7. Wigner quasiprobability distribution - Wikipedia

    en.wikipedia.org/wiki/Wigner_quasiprobability...

    Wigner quasiprobability distribution of squeezed states, for varying amount of phase shift and displacement. When the phase shift is zero (leftmost column), the peak-to-peak amplitude of oscillation is less uncertain, but the phase (the time at which crosses the midpoint) is more uncertain. The opposite is true when the phase shift is half a ...

  8. Spontaneous parametric down-conversion - Wikipedia

    en.wikipedia.org/wiki/Spontaneous_parametric...

    Schematic of SPDC process. Note that conservation laws are with respect to energy and momentum inside the crystal.. Spontaneous parametric down-conversion (also known as SPDC, parametric fluorescence or parametric scattering) is a nonlinear instant optical process that converts one photon of higher energy (namely, a pump photon) into a pair of photons (namely, a signal photon, and an idler ...

  9. Matching (statistics) - Wikipedia

    en.wikipedia.org/wiki/Matching_(statistics)

    Matching is a statistical technique that evaluates the effect of a treatment by comparing the treated and the non-treated units in an observational study or quasi-experiment (i.e. when the treatment is not randomly assigned).