Quantum-mechanical calculations of the mean-square fluctuation spectra in optical homodyning and heterodyning are made for arbitrary input and local-oscillator quantum states. In addition to the unavoidable quantum fluctuations, it is shown that excess noise from the local oscillator always affects homodyning and, when it is broadband, also heterodyning. Both the quantum and the excess noise of the local oscillator can be eliminated by coherent subtraction of the two outputs of a 50–50 beam splitter. This result also demonstrates the fact that the basic quantum noise in homodyning and heterodyning is signal quantum fluctuation, not local-oscillator shot noise.
© 1983 Optical Society of America
OSA Recommended Articles
OSA participates in Crossref's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.
Alert me when this article is cited.
Equations on this page are rendered with MathJax. Learn more.