The distribution and concentration of dopants in the core of an optical fiber, at low concentrations, particularly the rare earth dopants, are difficult to measure quantitatively. However, such information is critical to the determination of absorption cross sections of rare earth dopants in fiber amplifiers and the optimization of their performance. A number of different analytical techniques, such as secondary ion mass spectrometry (SIMS) and the electron probe microanalyzer (EPMA) were used here, along with prepared glass standards, to determine the Er concentration and distribution in optical fiber preforms containing Al, Ge and P. These results were compared with data obtained by neutron activation analysis (NAA) and x-ray fluorescence (XRF) which measure the average concentration of Er in the core. It has been shown that SIMS (and EPMA), in conjunction with NAA data can be used to establish, quantitatively, the Er concentration in the preform core, without the need for glass standards.

Lifetimes for the 4I13/2–4I15/2 transition of excited Er3+ ions in sodium di-silicate glasses have been measured as a function of Er3+ concentration and glass melting conditions. Lifetimes in excess of 20 ms have been measured for Er3+ levels up to 1021 ions/cm3. For Er3+ levels above 5 × 1020 ions/cm3 high lifetimes are only observed in glasses with low −OH impurity levels. The results are consistent with a quenching mechanism incorporating energy transfer between Er3+ ions followed by non-radiative decay via Er3+ ions coupled to the −OH impurity phonons.

Silica based multi-component glass fibers were fabricated using core glass doped with erbium concentration in the range of 650 to 34000wtppm. The highest gain of 18dB was achieved at the Er3+ concentraion of 7000wtppm under pump wavelength and power of 1.48μm and 40mW, respectively. The gain decreased at concentration over 7000wtppm due to clustering of Er3+ ions. The increases in the threshold value of the pump power caused by clustering of Er3+ ions was also recognized.

The excited state absorption (ESA) spectrum for Pr3+ doped ZBLAN glass is determined using a new technique based on the McCumber theory [D.E. McCumber, Phys. Rev. 136, A954 (1964)]. ESA peaks at 1380 and 840 nm are found, corresponding to transitions from the 1G4 to the 1D2 and 1I6 levels, respectively. ESA at the fiber amplifier pump wavelength 1.017 μm is found to be very small. The new method is also applied to Er+ doped glass, and good agreement is obtained between the resulting ESA spectrum and previous measurements using a traditional pump-probe technique.

An improvement in the quantum efficiency of the 1.3 μm transition of Pr3+ has been acheived as a result of doping alternative halide glasses. An increase from 3.4% in ZBLAN [1] to 9.9% in a multicomponent halide glass is reported.

The performance of Nd3+-doped fiber amplifiers is limited by strong excited state absorption (ESA) of the signal, even for fluorozirconate glasses where ESA prevents the important region below 1320 nm from being used. To quantify this and explore alternative host materials, ESA and stimulated-emission cross sections have been measured for a representative group of glass compositions. These parameters have been used in an accurate, fiber-amplifier model to provide the first quantitative comparisons of performance for Nd3+-doped glasses in the 1300-nm band as a function of host. A high-fluorine fluorophosphate is predicted to extend the short-wavelength boundary of the gain spectrum to 1295 nm but only at reduced gain levels and at the cost of having lower gains at longer wavelengths than fluorozirconates. A substantial increase in small-signal gain is predicted if the amplified spontaneous emission for the 1050-nm band is suppressed.

We describe the preparation and near Infra-Red fluorescence characteristics of a series of transition metal (V2+, Ni2+, Cr4+) doped crystalline inorganic materials. Within isostructural series, the effect of changes in the host lattice on the transition metal fluorescence has been investigated. This allows selection and fluorescence tuning of transition metal ion/crystalline host combinations of possible use for optical amplification in the 1.31 μm telecommunication window

Laser operation has been demonstrated in Tm3+-doped optical fibres at several useful wavelengths, including 2.3μm, 2μm, 1.47μm and 800nm, and visible upconversion fluorescence observed in silica and ZBIAN hosts. The ground-state Stark structure is ∼600cm−1 wide, resulting in broad tuning ranges for the lasers studied so far. As several of these laser are operated quasifour level using the ground state multiplet, the structure of this multiplet influences the laser transitions significantly. We Ipresent site-selective line-narrowed fluorescence studies of thulium in ZBLAN1 and silica-based hosts at low temperatures, which show detail of Stark levels not present in the room-temperature luminescence spectrum. Comparison of these data for Tmi: ZBLAN with the performance of fibre lasers and amplifiers based on the 800nm transition explains aspects of the laser performance such as tuning range, and optimum pump wavelength for amplifiers. In addition these data give information about the site-to-site disorder within the inhcmogeneous line.

Rare earth ions can easily be incorporated into fluoride glasses in moderate to large concentrations and, due to their low phonon energy, these glasses appear to have many advantages over oxide glasses as hosts for rare earth ions used in optical amplifiers and lasers. We have therefore investigated the optical properties of Pr3+, Pr3+/Yb3+ and Pr3+/Yb3+/Lu3+ doped bulk AIF3-based glass samples as a function of rare earth ion concentration. We find that the addition of 2 wt% of Yb increases the fluorescence of Pr3+ at 1.32 μm by a factor of 35 when excited with 488 nm radiation. The fluorescence intensity and excited state lifetimes are found to be comparable to those measured for Pr in a ZBLAN host. Since it has also been demonstrated that optical fibers drawn from AIF3-based glasses exhibit relatively low loss (< 0.05 dB/m) and posses superior chemical durability compared to other fluotide glasses, it is possible that AIF3 glasses may become the fluoride glass of choice for practical fiber laser and amplifier applications.

The results to be presented focus on the optimization of tellurite glass compositions which are suitable both for doping with erbium oxide as well as subsequent for fiber drawing. The laser related properties, such as fluorescence spectrum, lifetime, and optical transition cross sections will be presented. Judd-Ofelt parameters for erbium in the glasses have been exploited to predict fluorescence lifetime, excited state absorption(ESA), ground state absorption(GSA) and ground state fluorescence(GSF). For comparison, the absorption cross section, emission cross section, excited state absorption(ESA)/ground state absorption(GSA)(0.8μm pumping) and fluorescence terminating in the ground state(GSF)/excited state absorption(ESA) ratios are calculated for both Al2O3-SiO2 and tellurite glasses.

A comprehensive theoretical investigation of the 800-nm pump band for erbium-doped fiber amplifiers is presented. Both a silica and a fluorophosphate host are examined. To obtain the same amplification, the fluorophosphate requires 2–3 dB less pump power.

The role of glass composition is examined theoretically and experimentally for fiber amplifiers. Simple analysis procedures can be used to set limits on performance and identify more favorable glass types for detailed investigation.

Our work, in which we have studied optical nonlinearity trends in oxide glasses and the fabrication of optical fibers from high nonlinearity glasses, is reviewed. An oxide glass with a nonresonant nonlinearity Kerr coefficient g equal to 125 × 10−20 cm2/W, which is approximately fifty times larger than that of silica, was identified. Single-mode optical fibers have been fabricated from such high nonlinearity glasses. The predicted enhanced nonlinear properties of the fibers have been demonstrated without any significant degradation due to the nonlinear resonant process of two-photon absorption.

CdS-microcrystallites-embedded films of SiO2 were successfully prepared by rf-sputtering. The optical absorption edge of the film with 18.5 at% CdS clearly exhibited a blue shift by 0.13 eV compared to bulk CdS, indicating the quantum size effect due to confinement of electrons and holes in CdS microcrystallites. The blue-shift decreased with increasing the CdS concentration. The photoluminescence spectra of the films also exhibited the blue shift in band-edge emission. From decay curves of the band-edge emission, the dominant decay time was estimated to be 100 ps, and longer components were weak. Optical nonlinear susceptibility of the films was measured by degenerated four-wave mixing experiments near band-edge. The third-order nonlinear susceptibility was estimated to be 5.0 × 10−7 esu at 77K for the film with 46.3 at% of CdS.

An optical switch based on a single-mode fused coupler has been fabricated. The switch is worked by light induced refractive index change of an organic photochromic compound as cladding material in the coupling region. The splitting ratio of optical output at 1.3 μ m wavelength light can change 44.5%. The optical loss in the switch is less than 0.4

Since the realization of first polymer channel waveguides in the early 70ths and the market introduction of polymer fibres research work is aiming to increase the integration level of photonic circuits. This paper reports the state of the art in passive and active polymeric integrated optics in view of the requirements for practical applications in telecom and data processing systems.

The third order nonlinear responses for soluble one-dimensional ϕ-conjugated polymers, poly(3-alkylthiophene)s were investigated. Uniaxial stretching of the polymer film was carried out to align the polymer backbone. The stretched film showed large dichroism and crystallinity. Third order nonlinear susceptibility, χ(3)1111 of the stretched film was determined by optical third harmonic generation. A large enhancement of χ(3) due to the main chain alignment was observed.

The linear and non-linear optical response of phosphazene and siloxane polymers and cyclic precursors is influenced by the nature of chemical groups substituted onto the heteronuclear backbone chains. Polymer mechanical properties, chemical stability, and solubility also are affected. Significant variations in both second and third order susceptibilities have been measured for various substituted phosphazene materials. The electron donating tendency of substitutional groups appears to correlate with the measured non-linear optical properties determined by SHG and DFWM experiments in these systems where d¦-p¦ bonding along the polymer chain is important. Approaches to the synthesis, and deposition of these materials as thin films will be discussed. Variations in optical properties are highlighted for several model systems in terms of substitutional group perturbation to the chemical bonding between the chain heteroatoms.

Ultra-thin gold island films with optical anisotropy have been fabricated by stretching ordinary isotropic island films in the high temperature. The origin of optical anisotropy seems to come from an elongated prolate island shape.

An aqueous route to the deposition of complex metal oxide films is based upon the complexation of the corresponding metal nitrate salts by glycine, followed by spin-casting the concentrated solution onto silica substrates. The presence of glycine serves to frustrate precipitation and leads to the formation of a glassy matrix through which metal cations are homogeneously dispersed. Subsequent heating of coated substrates initiates an oxidation-reduction reaction which removes the organic matrix and residual nitrate leaving behind a film of the desired oxide composition. Using this method, ruby (Cr:Al2O3) and Sm:YAG (Sm:Y3Al5O12) films on the order of 150 nm thick have been deposited. The respective phases have been confirmed by XRD data and from the measured fluorescence spectra.

The red fluorescence exhibited by these materials under 488 nm excitation is dependent upon the ambient temperature and pressure. A marked shift in wavelength is observed as a function of increasing pressure. Ruby also exhibits a temperature dependent wavelength shift in contrast to Sm:YAG where a negligible shift is seen to temperatures near 1200 K. Fluorescence lifetimes of both materials exhibit a temperature dependence which varies with dopant concentration. This work suggests the possible application of these films as pressure-temperature sensors in a planar waveguide configuration or as a coating material for optical fibers. Details of the deposition process will be reviewed and the fluorescence response of both types of films will be summarized.