Mark H. Garrett

Impurity enhanced self-pumped phase conjugation in the near infrared in 'blue' BaTiO3

Abstract Photorefractive self-pumped phase-conjugation is examined at near-infrared wavelengths using doped ‘blue’ BaTiO 3 , and reflectivities are reported as high as 76% between 720 nm and 1004 nm due, as is believed, to a backward stimulated photorefractive scattering mechanism. Data also suggests that it is possible to stabilise the phase-conjugate reflectivity by vibrating the crystal.

Photorefractive properties of BaTiO 3 :Co

We measure and analyze beam-coupling gain and response time in BaTiO3 crystals doped with cobalt at levels of 50 and 100 parts in 106 for various oxidation and reduction states. We discuss the effect of cobalt doping and oxidation–reduction on the electron paramagnetic resonance and optical absorption of BaTiO3. We compare the BaTiO3:Co samples with nominally undoped and transition-metal- (chromium, manganese, iron, and iron + nickel) doped BaTiO3. We conclude that cobalt-doped BaTiO3 in the as-grown state displays high photorefractive gain that is correlated with the cobalt concentration in a reproducible manner. Cobalt appears to be the most promising transition-metal dopant for BaTiO3 investigated so far.

Intensity-dependent absorption and its modelling in infrared sensitive rhodium-doped BaTiO3

We investigated the intensity-dependent absorption coefficient of photorefractive Rh:BaTiO3 from the maximum (633 nm) to the near infra-red end (1.06 µm) of this crystals sensitivity. A numerical photorefractive model, incorporating dual-wavelength illumination and a secondary photorefractive centre, gives good agreement with experiment and shows that such a two-centre model is sufficient to explain the results obtained in the visible and infrared wavelength region

Growth, properties, and applications of potassium niobate single crystals

Production refinements and pragmatic optical properties of the frequency converter crystal KNbO3 (KN) are highlighted regarding its commercialization. The growth, morphological orientation, and processing of KN crystals into devices are outlined. Passive absorption data are presented that define the effective window range for KN devices. An absorption band at 2.85 micrometers is attributed to the presence of OH groups in the crystal, and its vibrational strength varies with crystal growth conditions and incident polarized light orientation. Although blue light induced infrared absorption (BLIIRA) can reduce second harmonic generation (SHG) efficiency at high powers, single-pass conversion efficiencies of 1%/W(DOT)cm may be achieved with incident fundamental powers of 10 W. The ability of KN to noncritically phasematch by temperature tuning provides blue-green wavelengths; together with critical angle-tuned phasematching, the entire visible spectrum may be accessed with efficient SHG conversion.