Abstract

We drive a high-efficiency gallium arsenide light emitting diode (LED) with a low-noise current and measure the noise in the detected photocurrent from a high-quantum-efficiency silicon photodiode collecting most of the emitted light. The drive current is obtained from a resistor in series with a low-noise voltage supply. The Johnson noise in the current is much less than shot noise whenever the voltage across the resistor is large compared with 50 mV (2kT/e at room temperature). The LED converts electrons to photons directly with some efficiency η.

© 1987 Optical Society of America