Nonlinear Optical Crystals: A Complete Survey

Frequency down-conversion of solid-state laser sources to the mid-infrared spectral range using non-oxide nonlinear crystals

High-intensity femtosecond pulses tunable in the 0.8–1.6-μm range have been generated by parametric amplification of a continuum white light in a new organic crystal, N-(4-nitrophenyl)-L-prolinol (NPP). The traditional concept of noncritical phase matching was revised in view of requirements linked to the observation of ultrafast subpicosecond nonlinear phenomena. The notions of θ (noncritical) and λ (noncritical) phase matching are introduced together with their applications. An experimental determination of phase-matching curves for both second-harmonic generation and three-wave mixing has been carried out. A θ noncritical phase-matching configuration for second-harmonic generation at 1.15 μm and a quasi-λ noncritical phase-matching configuration in the near IR for three-wave mixing were evidenced. Frequency and pump-intensity dependences of the gain have also been studied. Parametric emission at degeneracy was observed, with the emitted bandwidth extending from 1.0 to 1.4 μm. Time resolution of the amplified signal has been carried out by cross correlating the pump with the incoming signal, evidencing a reduced time broadening of the interacting pulses; a new spectroscopic method with subpicosecond time resolution is derived from the previous nonlinear optical characterization experiments by replacing the IR continuum from the water cell by any sample emitting in the same frequency range. This method, termed parametric amplification and sampling spectroscopy, was used for temporal analysis of amplified and emitted infrared signals generated in an NPP crystal.

Generation of high-peak-power tunable infrared femtosecond pulses in an organic crystal: application to time resolution of weak infrared signals

Refractive index interpolation in phase-matching.

Parametric oscillation and mixing

Optical parametric oscillation has been achieved in LiIO3 pumped by a pulsed ruby laser, with tunable output to 4μ. Operation of the singly resonant oscillator is described and threshold measurements are compared with theory.

Optical parametric oscillation in lithium iodate

A transverse excitation HF laser has been used to pump a singly resonant CdSe infrared parametric oscillator. Tunable output has been generated over the range 4.3–4.5 μm and 8.1–8.3 μm with peak powers of up to 800 W. By a combination of angle tuning and selection of HF pump wavelength, CdSe is phase matchable for generation of radiation from 3.0–4.8 μm and 7.8–22 μm.

Singly resonant CdSe parametric oscillator pumped by an HF laser

Laser‐induced generation of second‐ and third‐harmonic radiation is studied in cholesteryl nonanoate and in other cholesteric and nematic liquid crystals. No second harmonic is observed in any of the liquid‐crystal mesomorphic phases, indicating their ordered molecular arrangements to be centrosymmetric. Large changes in third‐harmonic intensity occur at several phase transitions, and their possible origins are considered.

Lawrence S. Goldberg

Papers

Optical parametric oscillation in lithium iodate

Singly resonant CdSe parametric oscillator pumped by an HF laser

Optical second‐ and third‐harmonic generation in cholesteryl nonanoate liquid crystal