Third and fifth harmonic generation of an IR (1.064 μm) pulsed laser has been produced in ablation plasmas of the wide bandgap semiconductors CdS and ZnS. The study of the temporal behaviour of the harmonic emission has revealed the presence of distinct compositional populations in these complex plasmas. Species ranging from atoms to nanometre-sized particles have been identified as emitters, a...

Magnetization-induced optical third-harmonic generation (MTHG) is observed in magnetic nanos-tructures: Co and F e nanolayers and granular films containing Co nanoparticles. Magnetization-induced variations of the MTHG characteristics in these nanostructures exceed the typical values of linear magneto-optical Kerr effect by at least an order of magnitude: the maximum of magnetic contrast in the...

Here we show what determines the optical resolution in laser microscopy. We define the expanded resolution limit (spatial frequency cutoff ) that includes the classic Abbe definition as 2 NA/λ, where λ is the wavelength. The resolution limit can approximate‐ ly be redefined as the frequency cutoff αNA/λ, where α is the constant that depends on the optical process occurring in the sample. In the...

Second-order nonlinear optical frequency conversion in isotropic systems is only dipole allowed for sum- and difference-frequency generation in chiral media. We develop a single-center chiral model of the three-wave mixing (sum-frequency generation) nonlinearity and estimate its magnitude. We also report results from ab initio calculations and from three- and four-wave mixing experiments in sup...

We examine the generation of terahertz (THz) by optical rectification of a fundamental infrared beam with its first harmonic in ionized air. From polarization measurements we identify an important, yet so far unreported (to our knowledge), cross term (chi(3)(xyxy)) + chi(3)(xyyx)) of the nonlinear susceptibility tensor. Omission of this term leads to an error by a factor of 10(6) of the THz int...

A large, dc-electric-field-induced nonlinear optical susceptibility is exploited to produce ultraviolet radiation in the range 2453-2476 A by the process of sum-frequency generation in sodium. The interaction is resonantly enhanced at the first intermediate level by the 3 (2)P(3/2) state and at the second intermediate level by a Rydberg state. Conversion efficiencies of 10(-5) have been obtaine...

Extended bis(donor)-substituted squaraine chromophores exhibit very high two-photon cross-sections (as high as 33 000 GM) in the near-IR; these can be attributed to the combination of large transition dipoles with small detuning energies. The modulus of the third-order nonlinear optical susceptibility at 1.3 mum has been found to be 7.0 x 10-11 esu for one of these chromophores.

Optimized second-harmonic generation (SHG) in quantum cascade (QC) lasers with specially designed active regions is reported. Nonlinear optical cascades of resonantly coupled intersubband transitions with giant second-order nonlinearities were integrated with each QC-laser active region. QC lasers with three-coupled quantum-well (QW) active regions showed up to 2 W of SHG light at 3.75 m wavele...

Nonlinear optical (NLO) frequency conversion materials have a significant impact on laser technology, optical communication and optical storage technology. The search for new frequency conversion materials over the past decade has led to the discovery of many semi organic NLO materials with high nonlinear susceptibilities. Among the semi organic NLO materials metal complexes of the thiourea hav...