Internal and external field fluctuations of a laser oscillator. I  Quantum mechanical Langevin treatment
Abstract
The amplitude and phase noise spectra of the internal and external fields of a laser oscillator are calculated using the quantum mechanical Langevin equations. The outgoing field spectra are demonstrated to be different from the internal field spectra. The outgoing photon flux from a laser oscillator operating at far above the threshold has a spectral density equal to the classical shotnoise level. On the other hand, the internal photon number spectrum is Lorentzian, and the variance is equal to the average photon number. The difference stems from the quantum mechanical interference between the transmitted internal field and the reflected zeropoint fluctuation at the output coupling mirror.
 Publication:

IEEE Journal of Quantum Electronics
 Pub Date:
 October 1986
 DOI:
 10.1109/JQE.1986.1072889
 Bibcode:
 1986IJQE...22.2032Y
 Keywords:

 Langevin Formula;
 Laser Cavities;
 Laser Stability;
 Noise Spectra;
 Power Spectra;
 Quantum Mechanics;
 Fourier Transformation;
 Population Inversion;
 Refractivity;
 Lasers and Masers