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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 ...
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.
Controlled heating of the crystal can be used to fine-tune phase matching in the medium due to a slight variation of the dispersion with temperature. Periodic poling uses the largest value of lithium niobate's nonlinear tensor, d 33 = 27 pm/V. Quasi-phase-matching gives maximum efficiencies that are 2/π (64%) of the full d 33, about 17 pm/V. [24]
Nonlinear photonic crystals are usually used as quasi-phase-matching materials. They can be one-dimensional, [1] two-dimensional [2] or three-dimensional. [3]
This would lead to beam walk-off, which limits the nonlinear optical conversion efficiency. Two other methods of phase matching avoid beam walk-off by forcing all frequencies to propagate at a 90° with respect to the optical axis of the crystal. These methods are called temperature tuning and quasi-phase-matching.
The interactions in PPKTP are based upon quasi-phase-matching, achieved by periodic poling of the crystal, whereby a structure of regularly spaced ferroelectric domains with alternating orientations are created in the material. PPKTP is commonly used for Type 1 & 2 frequency conversions for pump wavelengths of 730–3500 nm.
This makes it possible to artificially create an electric-field grating with arbitrary period, [7] which satisfies the condition necessary for quasi-phase-matching. Periodic poling is used for efficient frequency-doubling in optical fibers. [8]
He has analyzed the quasi-phase-matched hybrid interactions in periodically polled crystals (layer model), asymmetric modes of parametric solitons, properties of ultra-narrow quadratic solitons, propagation of ultra-short optical pulses inducing plasma generation, and parametric interactions of two non-axial vortices, methods of spatio-temporal ...