David E. Zelmon

Infrared corrected Sellmeier coefficients for congruently grown lithium niobate and 5 mol. % magnesium oxide–doped lithium niobate

The growth in the uses of lithium niobate for infrared applications has created a need for knowledge of its optical characteristics in the infrared spectral region for the purpose of designing phase-matched or quasi-phase-matched devices. We report measurements of the refractive indices of congruently grown lithium niobate and lithium niobate doped with 5 mol. % magnesium oxide. We use these results to predict the tuning curve of a room-temperature multigrating optical parametric oscillator in each material.

Molecular beam epitaxy growth of epitaxial barium silicide, barium oxide, and barium titanate on silicon

Thin‐film epitaxial structures of BaSi2, BaO, and BaTiO3, have been grown on the (001) face of silicon using ultrahigh vacuum, molecular beam epitaxy (MBE) methods. Source shuttering for the metal species coordinated with a pulsed, or cyclic, oxygen arrival at the growing oxide surfaces significantly improves film quality. The epitaxial growth of BaO is accomplished without silica formation at the BaO/Si interface by stabilizing BaSi2 as a submonolayer template structure. In situ ellipsometric measurements of the indices of refraction for BaO and for BaTiO3 in a BaTiO3/BaO/Si multilayer gave n=1.96 for BaO and n=2.2 for the BaTiO3, within 10% of their bulk values. These values suggest that this structure can be developed as an optical waveguide. BaO is impermeable to silicon for films as thin as 10 nm at temperatures as high as 800 °C, and good epitaxy can be obtained from room temperature to 800 °C. The epitaxy is such that BaTiO3(001)∥BaO(001)∥Si(001) and BaTiO 3〈110〉∥BaO〈100〉∥Si〈100〉.

Refractive-index measurements of undoped yttrium aluminum garnet from 0.4 to 5.0 μm

We report measurements of the refractive index of undoped yttrium aluminum garnet from 0.4 to 5.0 mum and the calculation of Sellmeier coefficients based on our data. The data differ considerably from previously published reports. The effect of the new data on the design of optical devices such as intracavity etalons for lasers is discussed.

Refractive-index measurements and Sellmeier coefficients for zinc germanium phosphide from 2 to 9 µm with implications for phase matching in optical frequency-conversion devices

Recent experiments in mid-IR frequency conversion reveal that older Sellmeier models for zinc germanium phosphide are inadequate for predicting phase-matching loci in zinc germanium phosphide optical frequency-conversion devices. This results in compromised device performance. We conduct a complete study of the refractive indices of zinc germanium phosphide from 2 to 9 µm and calculate new Sellmeier coefficients. The phase-matching calculations based on our new refractive-index data predict much more closely the results of several different mid-IR frequency-conversion experiments.

Electro‐optic, piezoelectric, and dielectric properties of zinc tris thiourea sulfate

Recently, it has been demonstrated that semiorganic materials have potential for very efficient nonlinear optical devices. Among many recently reported materials is zinc tris thiourea sulfate. We report measurements of the electro‐optic, piezoelectric, and dielectric constants of this new material.

Optical clarity and waveguide performance of thin film perovskites on MgO

The optical clarity of a new class of thin film waveguides, epitaxial perovskites on MgO, has been characterized and found to have optical clarity comparable to in‐diffused waveguide structures typically represented by Ti drifted LiNbO3. For the simplest member within this new class, SrTiO3, measurements of the wavelength dependence of optical loss show a monotonic decrease with increasing wavelength between 475 and 705 nm, reaching a value of 1 dB/cm at 705 nm.

Infrared properties of AgGaTe2, a nonlinear optical chalcopyrite semiconductor

The fundamental optical properties of AgGaTe2, a nonlinear optical semiconductor are reported. These properties include birefringence, indices of refraction, infrared transmission, and the temperature dependence of the band gap. The average index for wavelengths greater than several microns was found to be 3.0. The birefringence was found to be rather large and to range from a near band edge value of 0.038 at 1.3 μm to a value of 0.017 at 15 μm. Additionally, native defect related sub-bandgap absorption, photoluminescence, and electrical transport have been studied in these nominally undoped p-type crystals. An activation energy associated with these defects was determined to be 0.3 eV and the corresponding photoluminescence and absorption data showed, respectively, a broad asymmetric emission band centered at 0.8 eV and two bands at 0.95 and 1.01 eV, the absorption band at 0.95 eV being the most intense. The measured properties were utilized to assess the potential of AgGaTe2 for the wavelength conversio...

Rubidium titanyl arsenate difference-frequency generation and validation of new Sellmeier coefficients

Rubidium titanyl arsenate (RTA), a crystallographic isomorph of potassium titanyl phosphate, shows promise for nonlinear-frequency generation throughout the 1–5-µm spectral region. Difference-frequency generation in an RTA crystal produced tunable output in the 3.2–4.2-µm wavelength range. A single 1.064-µm Nd:YAG laser pumped both a LiNbO3 optical parametric oscillator used to generate a tunable signal beam and the RTA crystal used for difference-frequency generation. Conversion efficiencies were limited to 4% primarily by the large beam divergence of the signal beam. Phase-matching measurements were in excellent agreement with new IR-corrected RTA Sellmeier equations based on refractive-index measurements.

Optical properties of deuterated zinc tris thiourea sulphate

We report measurements of the optical properties of deuterated zinc tris thiourea sulfate (d‐ZTS). The material is being studied for its potential value in optical frequency conversion and electro‐optic applications. The electro‐optic and piezoelectric measurements along with those for the dielectric constant indicate that the figure of merit for electro‐optic modulation is comparable to that of KDP. However, careful refractive index measurements along with an analysis of the nonlinear coefficient tensor show that d‐ZTS will not noncritically phase match for second‐harmonic generation despite the promise shown by its undeuterated analog. In addition, the acceptance angle even for critical phase matching is very small.

Optical properties of Nd-doped rare-earth vanadates

Rare-earth orthovanadates are being used as substitutes for traditional solid-state laser hosts, such as YAG. While the most common of these is yttrium orthovanadate, other rare-earth vanadates, such as lutetium vanadate and gadolinium vanadate, are being used for their special properties in certain applications. We report new measurements of the refractive indices and thermo-optic coefficients of these materials, which will aid in the design of laser cavities and other nonlinear optical elements.