CIRCUIT-THEORY OF LASER DIODE MODULATION AND NOISE

The circuit theory of laser diode modulation and noise is based only on the energy and electron-number conservation laws, and on the well known expression hv(Gb + Ga) for the spectral density of Nyquist noise currents. The conductances Gb and Ga represent stimulated absorption and stimulated emission, respectively. This theory leads to results that are in exact agreement with the predictions of quantum optics even in the case of electronic feedback and non-classical states of light, but the optical field is not quantised. The theory is presented in a general form, applicable to arbitrary optical and electrical configurations, but is exemplified for only a single active element model of laser diode. For independent electron-hole injection, the results are the same as those obtained from standard rate equations, except for a phase-noise term. Important differences do occur for more realistic laser models.