Mark Andrew Newhouse

Nonlinear optical susceptibilities of high‐index glasses

We report results of degenerate four‐wave mixing measurements of nonresonant nonlinearities in a variety of high‐index lead and bismuth containing oxide glasses and the chalcogenide As2S3. The third‐order nonlinear susceptibilities of the oxide glasses are found to scale with the heavy metal content. A lead‐bismuth‐gallate glass was identified with a nonresonant χ3 equal to 42±7×10−14 esu, which is approximately three times larger than that of any glass previously reported.

Transparent glass-ceramics

Glass-ceramic materials may transmit visible light if either of the following conditions are operative: (i) the crystallites of all species are much smaller than the wavelength of visible light, or (ii) the optical anisotropy (birefringence) within the crystals and refractive index difference between crystals and glass are very small. These conditions are achieved in several aluminosilicate glass-ceramic systems. Solid solutions (ss) of β-quartz, spinel, and mullite are the major crystalline phases in these transparent glass-ceramics. The transparent β-quartz solid solution glass-ceramics can be divided into three areas: ultra-low expansion materials, refractory and colourless materials, and high electrical resistivity—low dielectric loss materials. These three material groups, though chemically distinct, are all characterised by high crystallinity, thermal shock resistance, excellent chemical durability, and susceptibility to mechanical strengthening by ion-exchange techniques.The transparent spinel and mullite glass-ceramics contain considerable glassy phase, but nevertheless are characterised by excellent transparency, even after thermal exposure for long periods above 1000° C.

Transparent glass ceramics for 1300 nm amplifier applications

The properties of an oxyfluoride glass ceramic that possesses high transparency after ceramming are described. Approximately 25 vol % of this material is comprised of cubic, fluoride nanocrystals and the remainder is a predominantly oxide glass. When doped with Pr+3, the fluorescence lifetime at 1300 nm is longer than in a fluorozirconate glass, suggesting that a significant fraction of the rare‐earth dopant is preferentially partitioned into the fluoride crystal phase. This material has the added advantage of being compatible with ambient air processing.

Resonant and non-resonant effects in photonic glasses

Abstract Over the past ten years, a large amount of research has been done investigating materials, both glasses and polymers, which exhibit large non-linear susceptibilities, χ 3 . The measured χ 3 for a wide range of inorganic glasses are presented and discussed in terms of chemical composition. The experimental results from a single mode fiber with a large non-resonant χ 3 are presented. An argument is made for the choice of the non-resonant non-linear effect in cylindrical optical waveguides as the most practical route toward the realization of devices utilizing non-linear interactions. The argument takes into account various aspects that influence device performance other than the magnitude of χ 3 alone. A brief discussion of the resonant non-linear phenomena derived from band-filling in semiconductor doped glasses and the photorefractive effect in SiO 2 GeO 2 waveguide materials is included for comparison.

Enhanced-nonlinearity single-mode lead silicate optical fiber.

A single-mode lead silicate optical fiber has been fabricated to permit lower-power all-optical switching. The core glass has a nonlinear index of refraction eight times that of silica. The loss of the fiber is less than 2 dB/m. Over 177pi of phase shift was obtained, as measured by self-phase modulation, in a 29-cm length of fiber. At the 1-kW peak power level required to produce this large phase shift, two-photon absorption and stimulated Raman scattering did not significantly degrade the desired nonlinear behavior.

Self-calibrating quantum efficiency measurement technique and application to Pr 3+ -doped sulfide glass

A measurement technique is described in which the radiative quantum efficiency of certain transitions in rare-earth-doped glasses can be determined based only on relative fluorescence measurements. We calibrate the emission from the level of interest by measuring emission into that level from a higher excited level. Application of the technique to Pr(3+)-doped sulfide glasses yields quantum efficiencies for the (1)G(4) ? (3)H(5) transition as high as 60%, in good agreement with measurements using the integrating sphere technique. Calculated efficiency values based on the Judd-Ofelt technique are shown to be subject to inherent uncertainties.

Pr-doped mixed-halide glasses for 1300 nm amplification

The pump efficiency of Pr-doped fluorozirconate amplifiers at 1300 nm is limited by nonradiative decay. A Pr/sup 3+1/G/sub 4/ excited state lifetime of 322 /spl mu/s has been obtained in a mixed-halide glass. This is 2.9 times longer than the lifetime in a fluorozirconate host. Numerical amplifier modeling combined with calculated emission cross sections predicts a comparable increase in amplifier pump efficiency. The mixed-halide /sup 1/G/sub 4/ emission is peaked at 1310 nm.<<ETX>>

Large effective area dispersion-shifted fibers with dual-ring index profiles

Summary form only given. In summary, we have designed and fabricated single mode dispersion-shifted fibers, using the dual-ring index profile, with effective area as large as 90 /spl mu/m/sup 2/. The large effective area can greatly reduce the performance degradation caused by fiber nonlinearities for long-haul terrestrial and submarine applications. Furthermore, these fibers show lower bending losses than standard step-index single-mode fibers.

Electric‐field‐induced birefringence properties of high‐refractive‐index glasses exhibiting large Kerr nonlinearities

The electro‐optic Kerr effect and its wavelength dispersion have been measured in glasses representing several compositional systems. The measured Kerr effect was found to be large for glasses having large refractive indices, including: (i) glasses containing high concentrations of the heavy metals Pb, Bi, and Tl; (ii) glasses with high Nb, Ta, and Ti content; and (iii) tellurite glasses. Comparison of the third‐order nonlinear susceptibility, χeff(ω = ω + 0 + 0), obtained from the measured electro‐optic data, to values estimated from literature values of the optical frequency value, χeff(ω = ω + ω − ω) suggest an opposition of the electronic and nuclear contributions to the low‐frequency electro‐optic effect for the glasses containing Ti, Ta, or Nb.

Praseodymium-doped cadmium mixed halide glasses for 1.3 μm amplification

Abstract In the search for suitable glass hosts for 1300 nm amplification, the field has been narrowed to Pr-doped fluorozirconate, fluoroindate, cadmium mixed halide and sulphide glasses. This paper presents data identifying the cadmium mixed halide system as a leading candidate, based on the lifetime and quantum efficiency of the1G4 →3H5 fluorescence of Pr3+ in this system. Compositional studies to develop cladding and core glasses suitable for high numerical aperture fiber, as well as relevant physical and optical properties, are also discussed.