Study on the Implementation of Optical Transparent Transport Networks in the European Environment—Results of the Research Project COST 239

Photonic Network Communications -     

Measurement of the effective phase-amplitude coupling factorαeff of high speed semiconductor optical amplifiermodulator

A semiconductor optical amplifier has been used as an external modulator. The large signal response has shown a 3-dB bandwidth of 3.1 GHz when the amplifier was saturated by the input optical wave. Moreover, the effective phase-amplitude coupling factor, which is a typical parameter of a semiconductor optical amplifier, was measured to be 8     

Structure and properties of ferroelectric PbZr0.2Ti0.8O3/YBa2Cu3O7 heterostructures

Epitaxial thin film PbZr_0.2Ti_0.8O₃/YBa₂Cu₃O₇ heterostructures have been grown on single crystal LaA10₃ by in-situ pulsed laser deposition. Structural characterization by x-ray diffraction, and transmission electron microscopy reveals that the films are typically c-axis oriented with a small fraction of a-axis oriented material, that is deposition condition dependent. The electrical properties change systematically with the crystalline quality and the best properties are obtained at higher temperatures. Above 715‡ C, there is progressive loss of lead and the electrical properties are diminished.     

Ferroelectric PbZr0.2Ti0.8O3 thin films on epitaxial Y-Ba-Cu-O

Abstract

Using a combination of pulsed laser deposition and sol-gel processing, we have fabricated epitaxial PbZr_0.2Ti_0.8O₃/YBa₂Cu₃O₇-x heterostructures on single crystalline [001] LaAlO₃. Rutherford back-scattering studies show the composition to be the same as the nominal starting composition. Transmission electron microscopy shows the existence of a randomly oriented polycrystalline microstructure in the PZT layer with a grain size of about 500–1000Å. Microscopic pores were also observed in the PZT layer. The PZT film exhibits ferroelectric hysteresis with a saturation polarization of 22–25μC/cm² (at 7.5V, 1kHz), a remanence of 5–6μC/cm² and a coercive field of about 40kV/cm.