Abstract

Amplitude-frequency correlation has received considerable attention since it plays a key role in determining the laser linewidth and the spectrum of the laser field. Effects due to that correlation have often been attributed to the amplitude-phase correlation, even though the two are not identical. It has been demonstrated that the magnitude of the amplitude-frequency correlation is directly proportional to the linewidth enhancement factor α¹ In a semiconductor laser, the product of the phase diffusion noise and the photon number uncertainty is, irrespective of α, larger than the minimum required by the uncertainty principle. Hence, amplitude and phase fluctuations are not necessarily uncorrelated. It is shown here, for the first time, that an amplitude phase correlation exists even if α is negligible. This fundamental correlation may find application in quantum noise reduction schemes.

© 1992 Optical Society of America