High-brightness, AlGaInP-based, visible light-emitting diode for efficient coupling with POF

A high-brightness light-emitting diode (LED) is fabricated using the AlGaInP based quaternary double heterostructure. The ring type electrode is used in the top contact in order to spread the current efficiently and also to enhance the coupling efficiency with the fiber. The fabricated LED has a light output as high as 1.7 mW at the bias current of 100 mA. The far-field radiation divergences are found to be approximately 100 and 70/spl deg/ for the LED's, with and without molding. These LED's offer coupling efficiency as high as 70% and 35%, with the step index (SI) plastic optical fiber (POF) after using the molded and hybrid ball lens, respectively. The increases of the coupling efficiency are due to the use of the ring-shaped top electrode, concentrating the emission mostly at the center.<
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