SIMULATION OF PHOTONIC NOISE IN OPTOCOUPLERS

The paper focuses on the total amount of noise reduction brought about by high impedance squeezing of shot noise in an optocoupler. A flexib le computer simulation method based on PSpice has been developed for s imulating shot noise and partition noise, both being fundamental quant um sources of noise in the optoelectronic system. Simulation results i nclude various output noise spectral densities of the optocoupler unde r different conditions of source impedance and quantum transfer effici ency. A noise reduction index (NRI) of the optocoupler is defined and simulation confirms that, with a large source resistance, the NRI appr oaches an upper bound limited by the quantum efficiency and the charge recombination time-constant of the light emitters.