Antonio C. Pastor

Elimination of Li2O out‐diffusion waveguide in LiNbO3 and LiTaO3

A novel technique was developed to eliminate the Li2O out‐diffusion waveguide in LiNbO3 and LiTaO3 incurred during the process of Ti in‐diffusion. The out‐diffusion waveguide can be suppressed by annealing the crystals in LiNbO3 powder at 900 °C in a flowing oxygen environment for 1 h or longer.

Aging effects in bulk and fiber TlBr‐TlI

A study of optical aging in bulk and extruded fibers of thallium bromo‐iodide (TlBr‐TlI) is presented. A variety of techniques including secondary ion mass spectrometry (SIMS), powder neutron and x‐ray diffraction, infrared spectroscopy, and electron paramagnetic resonance (EPR) spectroscopy are used to probe the chemical and structural properties of both pristine and aged material. High concentration levels of a hydrogen bearing impurity have been detected by SIMS and neutron scattering in aged TlBr‐TlI, and have been shown to be localized in the surface layers of fibers as well as bulk samples. We present EPR evidence which indicates that the hydrogen bearing impurity is water.

Lithography with new metallo-organic photoresists

Abstract A new method of depositing plain or structured inorganic films onto inorganic substrates without using evaporating or sputtering equipment is described. This method is based on the use of metallo-organic photopolymerizable compounds. Resist formulations for a large variety of metallo-organic photoresists are described. Oxide deposition is demonstrated and the deposition of metallic copper layers is described.

Single-Crystal Infrared Fibers Fabricated By Traveling-Zone Melting

Single crystal fibers of thallium, silver and cuprous halides have been fabricated by passing polycrys-talline extruded fibers through a small submillimeter melt zone, converting them to single crystal fibers. The lowest loss measured in a single-crystal fiber was 6.6 dB/m at 10.6 μm for AgBr, 620 μm in diameter and 80 cm in length.

Effect Of Water And Its Derived Impurities On Metal Oxides

Water, an ubiquitous impurity in all phases of materials processing, degrades the near-infrared transmission of metal halides and oxides. With the halides, one deals with both the oxygen and hydrogen impurities derived from H2O, while with the oxides, only the H-impurity. The electrolytic and thermal dissociation modes of H2O become significant at the much higher process temperature of the refractory metal oxides. Because of the high strength of the oxide ion as a Lewis base, halogen atoms are unable to abstract the proton of the H-impurity. However, they can displace by electron transfer the H-impurity as the unit OH, a pseudohalide. The limitation and application of the use of halogens to clean up H-impurities in metal oxides are demonstrated with the use of basic and acidic metal oxides.

Lithography With Metallo-Organic Resists

Photolithography with metallo-organic resists is a relatively new addition to photo-engraving technology, and involves the chemical incorporation of inorganic constituents into photopolymerizable organic compounds, so that the photoresist functions not merely as a masking material, as in conventional photolithography, but also as the mass transference vehicle itself. The deposition of thin structured films of metal oxides with this method has been accomplished, the metal-doped resist in each case being the metal acrylate in acrylic acid, except in those cases where the metal acrylate was insoluble. Polymerization was effected with uv irradiation. The criteria for depositing other classes of inorganic compounds are outlined.