Allan James Bruce

Calcium aluminate glasses as pontential ultralow-loss optical materials at 1.5–1.9 μm

Abstract The suggestion made in an earlier paper, that the calcium aluminate (CA) family of glasses should exhibit intrinsic optical losses at 1.55 μm, markedly lower than the 0.16 dB/km of SiO2, is confirmed by scattering measurements. The total (i.e. Rayleigh, Brillouin and Raman) scattering losses are found to be ≈ 0.04 dB/km at 1.55 μm with a projected minimum total attenuation for pure silica-free samples of as low as 0.015 dB/km at ≈1.9 μm. Measurements are also made of multiphonon edge absorption in the 4–6 μm regime and a preliminary assessment given of the materials outlook for the preparation of ultralow-loss CA-glass fibers.

Concentration-dependent /sup 4/I/sub 13/2/ lifetimes in Er/sup 3+/-doped fibers and Er/sup 3+/-doped planar waveguides

We report on the concentration- and pump-dependent lifetimes of the spontaneous emission in Er/sup 3+/-doped fibers and Er/sup 3+/-doped waveguides. In addition, we measure the concentration dependence of the 550-nm fluorescence due to excited state absorption (ESA).<<ETX>>

8-mV threshold Er/sup 3+/-doped planar waveguide amplifier

We report on the gain characteristics of a low threshold (8 mW) Er/sup 3+/-doped planar optical waveguide amplifier. Net fiber to fiber gain of 4.5 dB is achieved at a signal wavelength of 1536 nm with 80 mW of 980-nm pump power. This device represents significant progress toward a planar amplifier module pumped by a single laser diode.

Performance of a high concentration Er/sup 3+/-doped alumino silicate fiber amplifier

We report the gain, noise figure, output saturation power, and conversion efficiency of a highly concentrated Er/sup 3+/-doped alumino silicate fiber amplifier. We obtain a gain per unit length of 1.0 dB/cm, which corresponds to the highest gain per unit length obtained in an Er/sup 3+/-doped fiber amplifier. The pump power threshold ranges from 2 to 5 mW, depending on the fiber length.

Multicomponent glasses from particulate gels

Abstract The principles of making multicomponent glasses from particulate gels are discussed and the applications of these principles in the synthesis of bulk samples of low-alkali high-silica glasses containing up to 6 mol% Li 2 O, K 2 O, Rb 2 O or Cs 2 O and up to 3% Al 2 O 3 are described. Several samples were also doped with Er 3+ and Nd 3+ . A feasibility study directed at the preparation of entire-gel optical fiber performs was conducted. It is shown that the impregnation of the inner surface of a low-alkali gel tube with Al 3+ - and Er 3+ -containing solutions can yield, after sintering, a glass tube with sharp compositional and refractive index profiles. The results of this study indicate that bulk samples of previously unavailable multicomponent glasses can be fabricated from particulate gels. The boron-free glasses prepared in this study have low thermal expansion (between silica and Pyrex®), relatively low T g (750–800°C) and softening temperatures and may be considered for applications in planar waveguide technology based on silicon.

EDWA: key enabler of optical integration on PLC

One of the trends that persist in the telecom industry in all market conditions is a continuous push towards lower cost and higher performance optical components. Unlike today’s networks, a more cost efficient network of tomorrow will contain many components utilizing Planar Lightwave Circuits (PLC) technology. PLC technology is a platform for optical integration that could dramatically lower cost-per-function in many optical networks. However, integration may result in degraded optical performance due to higher insertion losses as compared to “standard” fiber-based solutions. A solution to the loss problems is an optical amplifier that can be integrated on the same PLC platform and used to restore optical signals as needed. Inplane Photonics is developing Er-doped waveguide amplifier (EDWA) technology, which is fully compatible with a glass-on silicon PLC platform. We identify that an EDWA is a necessary building block to achieve the full potential of optical integration. In this paper we will present recent EDWA performance that approaches that of an EDFA. Furthermore, we will demonstrate several examples of practical integration between passive and active building blocks on a single PLC chip.

Size effects on the superconducting properties of polycrystalline aggregates of Ba2YCu3O7−δ cuprates

Abstract A.C. magnetic susceptibility measurements have been performed on polycrystalline aggregates of Ba 2 YCu 3 O 7− δ superconducting cuprates ranging in size from 40 μm diameter granules to 3 mm × 3 mm × 5 mm bulk pieces. The susceptibility transition near 90K broadens and becomes progressively shallower for the smaller size aggregates. This phenomenon has been used to follow the consolidation of small aggregates during sintering between 450–950°C in an oxygen atmosphere. Significant consolidation occurs at and above 850°C allowing the possibility of sintering at somewhat lower temperatures than previously anticipated. The influence of atmospheric moisture appears to be minimal.

Structural and electronic characteristics of Cu(In,Ga)Se 2 thin films sputtered from quaternary targets

Although the advantages of sputter deposition for large area, uniform deposition are well known, it has long been believed that sputtering Cu(In,Ga)Se2 (CIGS) from a quaternary sputtering target yields films with morphological and electronic properties that make them unsuitable for use in high-efficiency photovoltaic devices. Recent work, however, has demonstrated that this deposition method can produce dense, polycrystalline, highly oriented films with the desired stoichiometry. Devices built with these films exhibit efficiencies >;10%. While effective parameters for target composition and deposition conditions have been achieved, variation from these conditions can result in a wide array of morphologies, even while composition remains near that of stoichiometric CIGS. In this paper, we review the broad range of structural and electronic properties that result from various sets of target compositions and deposition conditions. Films deposited under some conditions are similar in important respects - their composition, a dense structure composed of ~1 μm sized grains, and the presence of a MoSe2 layer - to those of evaporated CIGS. We discuss how these results point towards the possibility of higher-efficiency sputtered CIGS.

Characterization of Cu(In, Ga)Se 2 thin films and devices sputtered from a single target without additional selenization

Typically, Cu(In, Ga)Se 2 (CIGS) thin films for photovoltaic devices are deposited by co-evaporation or, alternately, by deposition of the metals with, or followed by, treatment in a selenium environment. In this proceeding, we describe CIGS films that are instead deposited by RF magnetron sputtering from a single quaternary target without any additional selenization. Devices built with these films exhibit efficiencies as high as 9.9%. These results represent the first report of working CIGS devices fabricated by sputtering without additional selenization. We demonstrate that deposition power can be varied in order to change the film morphology and improve device performance.

Inplane's technology platform for subsystems on a chip

Planar waveguide technology has long been touted as the major platform for optical integration, which could dramatically lower component/module size and cost in optical networks. This technology has finally come to maturity with such waveguide-based optical products as wavelength multiplexers, switches, splitters and couplers, which are common nowadays. However, its potential as a complete solution for integration of a subsystem on a chip has so far been limited by the lack of integrated active elements providing gain to deteriorating optical signals. As the signal propagates through the fiber-optic network, it dissipates its energy and requires amplification in the network subsystems to maintain a required signal to noise ratio. Discrete fiber amplifiers are designed into systems and maintain required signal levels. However, if new components are introduced or the current ones are changed, current amplifiers have a limited ability to compensate for changes. Inplanes solution to the signal degradation problem is an optical amplifier that can be integrated onto the same planar waveguide platform as the other passive elements of the subsystem. Subsystems on such a platform will be able to automatically and internally adjust signal optical power, and enable simple interfacing between optical modules, module replacement and upgrades in the network. Inplane Photonics has developed Er-doped waveguide amplifier (EDWA) technology, which is fully compatible with the glass-on-silicon waveguide platform. In this paper we will present recent EDWA performance that approaches that of a fiber amplifier. Furthermore, we will demonstrate several examples of practical integration between passive and active building blocks on a single optical chip.