NOISE IN AN OPTICAL AMPLIFIER - FORMULATION OF A NEW SEMICLASSICAL MODEL

After pointing out some questionable assumptions of the standard beati ng theory, we formulate a new semiclassical wave theory of the noise i n optical amplifiers, The theory is simple yet rigorous and uses a few quantum statements in a classical signal framework, The amplifier is modeled as a 2 x 2 port device, and the amplified spontaneous emission and associated noise are shown to be just the amplified coherent stat e (or vacuum state) fluctuation of the field entering the idler input, The new theory can treat other closely related detection schemes as w ell, correctly supplying both mean signal and noise.