Abstract

The rapid development of lightwave communications has created a demand for high-performance receivers for a variety of systems applications. For many of these applications, e. g. local area networks, cost is a primary consideration. It is expected that integration of the receiver components will eventually yield significant savings with little or no loss in performance. To date, most of the integrated receiver circuits that have been reported have combined p-i-n photodiodes with FET amplifier circuits¹. Alternatives to the p-i-n/FET approach are a p-i-n or a phototransistor coupled to a bipolar amplifier circuit². One motivation for the use of a phototransistor/bipolar configuration for integrated receiver circuits is better materials compatibility than p-i-n/FET circuits. A typical p-i-n photodiode structure consists of a lightly doped epitaxial absorbing layer on a heavily doped substrate. The FET amplifier circuit, on the other hand, requires a heavily doped channel on a semi-insulating substrate. In contrast, the phototransistor is functionally just a p-i-n photodiode integrated with a bipolar transistor in the common collector configuration and therefore can be fabricated from the same epitaxial layers used for a bipolar amplifier. Recently, Wang et al. have reported an all-bipolar photoreceiver for λ ≈ 0.85 μm consisting of a GaAs/AlGaAs heterojunction phototransistor (HPT) and GaAs/AlGaAs heterojunction bipolar (HBT) amplifier³. In this paper, we report, for the first time, an InP/InGaAs integrated receiver circuit which utilizes an HPT as the photodetector and a bipolar amplifier circuit. This circuit operates in the wavelength regions near 1.3 μm and 1.5 μm.

© 1989 Optical Society of America