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We report the results of a study of the optical gain properties of binary blend films of regioregular poly(3-hexylthiophene) (RR-P3HT) and poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT). Efficient optical gain is observed in the 10-20 wt. % RR-P3HT composition range and can be tuned to the ∼650 nm window utilised for polymer optical fibre data-communications, with maximum gain ∼50 cm-1. At higher P3HT fractions, gain thresholds increase substantially, consistent with the observed concomitant improvement in photocharge generation. Distributed feed back lasers with one-dimensional gratings exhibit pump pulse thresholds as low as 8 nJ (26 μJ cm-2, 2.17 kW cm-2), lower than many other polymer-based gain media in this wavelength range. They also provide relatively high slope efficiencies >2%. The confluence of efficient optical gain with electronic properties that are conducive to charge carrier injection and transport is relatively novel and is expected to be a necessary requirement for the achievement of electrically pumped lasing. [ABSTRACT FROM AUTHOR]

A three-segment laser, when separately pumped, shows both frequency switching and continuous tuning with a modulation current applied to the middle segment. The wavelength changes are attributed to gain peak shift with the carrier concentration and carrier-induced index change. A total wavelength change of 61 Å, a continuous tuning range of 4.1 Å, and a tuning rate of -0.74 Å/mA are obtained. The laser may be useful in optical FM fiber communication. [ABSTRACT FROM AUTHOR]

Techniques for passivating In0.53Ga0.47As, InGaAsP, InP, and InGaAsP/InP p-n junction structures with polyimide have been developed. Low stable leakage current is maintained for prolonged bias, even after exposure to high temperatures (∼320 °C) during packaging. 150-μm-diam In0.53Ga0.47As photodiodes with a breakdown voltage of ∼50 V were passivated with polyimide and were found to consistently have leakage currents of ∼10 nA at a 20-V bias.Details of the passivation process are given. [ABSTRACT FROM AUTHOR]