Heavy metal fluoride glasses with low intrinsic Rayleigh scattering

The results of Rayleigh light scattering measurements in bulk multicomponent fluorozirconate glasses are described. We observe for the first time that such materials may be reproducibly prepared with uniformly low scattering levels throughout their volume. In 13 of the 15 specimens studied, the magnitude of the Rayleigh scattering loss was one-third to one-half that typically observed in fused silica glass.     

Material dispersion in fluoride glasses

Material-dispersion measurements are reported on fluoride glass for infra-red optical fibres. Bulk glasses prepared by the conventional casting method were measured in the 0.4?4.3 ?m wavelength range. Observed zero-material-dispersion wavelengths were 1.62 ?m for BaF2-GdF3-ZrF4 glass and 1.48 ?m for BaF2-CaF2-YF3-AlF3 glass.     

Reduction of OH-absorption in fluoride glasses

The thermodynamics of hydrolysis reactions show that hydroxyle groups are not stable in glass melt at high temperature. A refining stage carded out at 1000°C for 1 h results in low-OH-content bulk glasses. Preforms were prepared by this method and drawn into fibers. The maximum absorption of 2.9 μm was 110 dB/km and a minimum transmission loss of 16 dB/km was observed at 2.6 μm.     

Multiphonon absorption in infra-red fluoride glasses

Measurements of the infra-red edge absorption against frequency have been performed with both ZrF4 and HfF4 fluoride glasses. Results show that absorption in the 1600?1200 cm?1 frequency range (6?8 ?m band) originates from multiphonon processes and depends on the glass composition.     

Stimulated Brillouin scattering in glasses

An experiment is described in which the laser-fracture threshold of glass is compared with the stimulated-Brillouin-scattering threshold and intensity. It is demonstrated by means of an alteration of the laser-emission spectrum, which acts on s.B.s. and not on fracturing, that the two effects are not related.     

Photosensitivity of rare-earth-doped ZBLAN fluoride glasses

We have performed experiments to elucidate the mechanism of photosensitivity in rare-earth-doped fluorozirconate (ZBLAN) glasses. Glasses doped with Ce, Tb, Tm, and Pr were studied. Permanent holographic gratings were written in bulk samples using 248 nm light, with the strongest gratings observed in Ce:ZBLAN. Ultraviolet (UV) induced changes in both absorption and electron spin resonance (ESR) spectra were observed. In the Ce-doped glasses, the grating formation dynamics were recorded as a function of write beam intensity and Ce concentration. The results indicate that the mechanism of photosensitivity involves color center(s) creation through a stepwise two photon excitation of a Ce ion. The color center(s) can be subsequently bleached by a single photon at 248 nm     

Viscosity and optical measurement on fluoride glasses

Scattering loss and viscosity against temperature measurements have been carried out on fluoride glasses. The results indicate for the first time a ?-4 behaviour for scattering loss in the 0.45?0.75 ?m wavelength range. Activation energies for viscous flow were found to be similar for both ZrF4? and HfF4?based glasses.     

Dispersion measurement on fluoride glasses and fibers

An overview is given of dispersion measurements on fluoride glasses and fibers, and the dispersion compensating capability of fluoride fibers is discussed. The temperature dependence of refractive-index dispersion and material dispersion of fluoride glasses is measured. These measurements indicate that fluoride glasses can compensate for temperature-dependent changes of refractive indices and material dispersion in silica glasses and fibers     

Rayleigh scattering in ZrF4-based glasses

Light scattering in a 51.53 ZrF4 - 20.47 BaF2 - 5.27 LaF3 - 3.24 AlF3 - 19.49 LiF glass was investigated for the first time both as a function of wavelength and of angular distribution. The measured total scatter loss exhibits a characteristic Ray-leigh ?-4 dependence. The total scattering attenuation coefficient has been reduced to that of the best synthetic silica, and nearly reaches the theoretically predicted minimum.     

Efficient frequency up-conversion via energy transfer in fluoride glasses

The conversion of infra-red to visible light has been studied in a series of fluoride glasses doped with YbF3 and ErF3. The frequency up-conversion efficiency of these bulk materials is four orders of magnitude greater than that observed in doped oxide glasses, and compares very favourably with results obtained for Yb3+/Er3+-containing crystals.     

基于透射光谱的类金刚石膜光学参数反演

为解决光谱反演法确定透明固体光学常数的一些问题,如存在反演误差、计算耗时等。本文基于传统的双厚度透射率模型,建立了厚度满足整数比的两个光谱透射率方程。通过代数运算获得了与消光系数有关的多项式方程,求解并选择大于0小于1的实数根来计算消光系数;然后求解关于界面反射率的一元二次方程,选择大于0小于1的根来计算折射率。在确定光学常数的过程中,新方法没有反演误差、迭代计算耗时及多值问题。作为应用示例,利用已知文献中的双厚度透射率实验数据计算了CaF₂和Si的光学常数,并和文献的结果进行了比较。结果表明,新方法优于传统的光谱反演法,新方法为透明固体光学常数的高精度确定提供了新选择。     

Heavy metal fluoride glasses and fibers: A review

A comprehensive summary is provided on the subject of heavy metal fluoride glasses. This includes discussions on glass compositions, preparation, structure, fiber drawing characteristics, and intrinsic and extrinsic optical properties. Other relevant glass and fiber characteristics such as strength, durability, and thermal Shock resistance are also outlined. Particular emphasis is given to the measurements of optical attenuation in fluoride glasses and their potential for use in ultralow-loss fiber optic waveguides. An excellent bibliography of recent work in the area of heavy metal fluoride glasses has been generated for those seeking more detailed information on this topic.     

Dehydration of fluoride glasses by NF3processing

Reactive atmosphere processing with a NF3gas is employed in the preparation of fluoride glasses to remove hydroxides in the glasses. The hydroxides are effectively removed by NF3processing without any resultant increase in the scattering.     

Optical waveguides in fluoride lead silicate glasses fabricated by carbon ion implantation

The carbon ion implantation with energy of 4.0 MeV and a dose of 4.0×1014 ions/cm2 is employed for fabricating the optical waveguide in fluoride lead silicate glasses. The optical modes as well as the effective refractive indices are measured by the prism coupling method. The refractive index distribution in the fluoride lead silicate glass waveguide is simulated by the reflectivity calculation method (RCM). The light intensity profile and the energy losses are calculated by the ?nite-difference beam propagation method (FD-BPM) and the program of stopping and range of ions in matter (SRIM), respectively. The propagation properties indicate that the C2+ ion-implanted fluoride lead silicate glass waveguide is a candidate for fabricating optical devices.     

Brillouin scattering and phonon attenuation in halide glasses: stimulated Brillouin emission

The results of Brillouin light scattering measurements in bulk halide glasses are described. The Brillouin linewidth, intensities and frequency shift measurements allowed the calculation of phonon attenuation, Pockels' elasto-optic coefficients and stimulated Brillouin scattering gain coefficients. The above study shows that the threshold power for stimulated Brillouin scattering in some halide glasses is greater than that for silicate glasses.     

氟磷酸盐激光玻璃光散射和激光破坏原因的研究

在氟磷酸盐激光玻璃中,由分相和析晶产生的固体夹杂物是光散射和激光损伤的主要原因。Fe、Cu;Ni、Si等杂质的不均匀沉积作用,使激光破坏阈值进一步降低。     

Fluorescence dynamics of Er3+ and Ho3+ ionsand energy transfer in some fluoride glasses

A detailed study at room temperature of the fluorescence dynamics of Er³⁺ and Ho³⁺ ions and energy transfer processes Er³⁺→Ho³⁺ in the ABLA, BATY, and BIZYT fluoride glasses is reported. Numerous concentrations and different selective laser excitations in the visible and infrared spectral ranges are used. The best concentrations and the more suitable glasses for laser applications at 2 μm are determined