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The photochemical reaction of Ge[sup 2+] in 10GeO[sub 2]-90SiO[sub 2] optical fiber preform and the origin of the 5.7 eV optical absorption band induced by intense ultraviolet laser excitation have been investigated using a near-ultraviolet XeF excimer laser (3.7 eV) as the main excitation source. Based on the previous and present experimental results, it is concluded that the 5.7 eV optical absorption band does not originate from the Ge(2) electron trapped center. In place of this model, we have proposed an alternative structural model for the origin of the 5.7 eV band taking into account the experimental fact that the corresponding center is diamagnetic. In addition, it is found that the site selective excitation of the Ge[sup 2+] center can be achieved by using laser sources with different photon energies. [ABSTRACT FROM AUTHOR]

Presents information on a study pertaining to the up-conversion characteristics of Er3+ in transparent oxyflouride glass-ceramics. Information on the intensities of up-conversion emissions; Object of the study; Results of study.

Thermo-optic characteristics of organically modified SiO2–ZrO2 films prepared by a nonhydrolytic reaction have been investigated. The thermo-optic coefficient (dn/dT) is negative on the order of -10-4/K and varies with the wavelength as a function of the ZrO2 content in organically modified SiO2 material. As the amount of ZrO2 increases, the wavelength dependence of dn/dT gradually varies from positive to negative. The magnitude and wavelength dependence of dn/dT for organically modified SiO2–ZrO2 hybrid materials make these materials highly flexible for application in thermo-optic integrated devices. [ABSTRACT FROM AUTHOR]

Microstructures were fabricated by a photothermal process in a low-melting organic-inorganic hybrid material of tin silicophosphate doped with Nd3+ ion as a light absorber. The negative refractive index change of the order of 10-3 was photothermally induced inside the low-melting glass with a spatial resolution ranging from 10 to 100 μm using a 514.5 nm emission from an Ar+ laser of less than 30 mW as the excitation source. The volume expansion due to the photogenerated heat at the laser focus is found to be responsible for the photothermally induced negative photorefractive index change. [ABSTRACT FROM AUTHOR]

Examines second-harmonic generation (SHG) in germanosilicate glass poled with argon fluoride laser irradiation. Measurement of the SHG coefficient; Effect of increasing poling field; Observation of anisotropic refractive index.

Examines the upconversion luminescence characteristics of erbium cations in CdX[sub 2]-based halide glasses (X=CI, Br, of I). Details on the linewidth of green emission for halide glasses; Observation of blue upconversion luminescence for CdCl[sub 2] and CdBr[sub 2] system glasses; Dependence of multiphoton relaxation rate on the phonon energies of hosts.

Examines the upconversion luminescence of erbium cations in the chloride glass system based on zinc chloride and cadmium chloride. Luminescence emissions of the structures at 800 nanometer excitation; Comparison of blue emission intensity with other Er[sup 3+]-doped systems; Source of the blue and green upconversion luminescence.

In a 15.7 GeO[sub 2]·84.3 SiO[sub 2] glass prepared by a vapor axial deposition method, optical absorptions at 4.92 and 5.08 eV were observed from 300 to 600 K. The results were then compared with electron spin resonance (ESR) measurement using the same samples. The absorption at 4.92 eV was found to increase with increasing temperature, while the optical absorption at 5.08 eV decreased with increasing temperature. These changes of optical absorption indicate that the concentration of neutral oxygen monovacancy is reduced at higher temperatures. The changes were quite reversible with the temperature. Concentration of Ge E[sup ′] center, estimated from ESR, increased with increasing temperature, which is in contrast with the decrease of neutral oxygen monovacancy. The present result strongly suggests the thermal equilibrium reaction between neutral oxygen monovacancy and Ge E[sup ′] center. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The spontaneous emission coupling factor β is studied for fiber-coupled microspheres with a thin gain layer of phosphorus codoped sol-gel erbium silica-aluminum glass. From the input-output characteristics of the lasing, β=0.039 is estimated for a sample with a gain layer on the sphere surface. β is estimated to increase to 0.19 when an additional silica glass thin layer is overcoated to improve the overlap between the gain layer and the optical mode of the lasing inside the sphere. [ABSTRACT FROM AUTHOR]

Lasing of a taper-microsphere system with a gain layer of submicrometer thickness is demonstrated. For the gain layer, an Er3+-doped P2O5–Al2O3–SiO2 thin film with a thickness of 200 nm was fabricated using the sol-gel method on a silica microsphere. The demonstration of single-mode lasing with the thin gain layer suggests the improved dispersion of Er ions in the P codoped gain layer. [ABSTRACT FROM AUTHOR]