The theory of quasi-phase-matched second-harmonic generation is presented in both the space domain and the wave vector mismatch domain. Departures from ideal quasi-phase matching in periodicity, wavelength, angle of propagation, and temperature are examined to determine the tuning properties and acceptance bandwidths for second-harmonic generation in periodic structures. Numerical examples are tabulated for periodically poled lithium niobate. Various types of errors in the periodicity of these structures are then analyzed to find their effects on the conversion efficiency and on the shape of the tuning curve. This analysis is useful for establishing fabrication tolerances for practical quasi-phase-matched devices. A method of designing structures having desired phase-matching tuning curve shapes is also described. The method makes use of varying domain lengths to establish a varying effective nonlinear coefficient along the interaction length. >

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Quasi-phase-matched second harmonic generation: tuning and tolerances

Handbook of optics

Standards which eliminate ambiguity in reporting nonlinear phenomena, especially in the increasingly complex realm of biaxial crystals, are proposed. In order to restore uniformity to the designation of crystallographic axes and crystal tensor properties, adoption of IEEE/ANSI Std. 176, with a small but much needed modification for crystal class mm2, is recommended. For the reporting of nonlinear interaction characteristics, other frames are proposed which result in simpler rules than heretofore given for categorizing phase-matching loci, and for characterizing eigenmode polarizations, double refraction, effective nonlinear coupling, and first- and second-order acceptance bandwidths (angular, spectral, thermal) along these loci. Similarities as well as differences between biaxial and uniaxial crystals are emphasized. >

Simplified characterization of uniaxial and biaxial nonlinear optical crystals: a plea for standardization of nomenclature and conventions

We consider a technique for high-resolution image upconversion of thermal light. Experimentally, we demonstrate cw upconversion with a resolution of more than 200 × 1000 pixels of thermally illuminated objects. This is the first demonstration (to our knowledge) of high-resolution cw image upconversion. The upconversion method promises an alternative route to high-quantum-efficiency all-optical imaging in the mid-IR wavelength region and beyond using standard CCD cameras. A particular advantage of CCD cameras compared to state-of-the-art thermal cameras is the possibility to tailor and tune the spectral response leading to functional spectral imaging.

High-resolution two-dimensional image upconversion of incoherent light

In dispersive media the bandwidths of generated sum- or difference-frequency pulses can be greatly enlarged by use of previously chirped generating waves. It is shown that this technique is even more advantageous for shorter pulses and at a higher dispersion regime of the crystal. Experimental examples are also discussed.

Broadband sum-frequency generation by chirp-assisted group-velocity matching

A systematic evaluation of the spectral bandwidth and two acceptance angles of parametric generation processes is presented. The spectral bandwidth and acceptance angles are determined by expanding the wave vector mismatch in a Taylor series and retaining terms through second order. This allows a determination of these parameters even when the first order term vanishes. Conditions where the first order term vanishes are presented and compared with similar cases where the first order term does not vanish.

Parametric generation processes: spectral bandwidth and acceptance angles

Randomly spaced phased arrays with large interelement spacing

The concept of a phased array of far infrared or submillimeter waveguide lasers that can be scanned electronically is presented. Grating lobe reduction by computer analysis is shown. The application in a low angle track-while-scan radar is discussed.

Vincent J. Corcoran

Papers

Parametric generation processes: spectral bandwidth and acceptance angles

Randomly spaced phased arrays with large interelement spacing

Far Infrared — Submillimeter Phased Arrays