The 6N135, 6N136 series combine an AlGaAs infrared emitting diode as the emitter which is optically coupled to a silicon high speed photo transistor in a plastic DIP8 package with different lead forming options. A separate design between photodiode and transistor reduces the base collector capacitance of the input transistor which improves the speed by several orders of magnitude over conventional phototransistor optocouplers.