Squeezed states in direct and coherent detection
- Cite this article as:
- Annovazzi-Lodi, V., Donati, S. & Merlo, S. Opt Quant Electron (1992) 24: 285. doi:10.1007/BF00619404
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With reference to squeezed states, we analyse the noise performances of the basic detection schemes in fibre telecommunications and interferometry. We have developed a semiclassical approach that allows us to translate the quantum mechanical formalism into synthetic expressions and rules only involving directly measurable physical quantities. As a result, we find that in the telecommunication field squeezed states do not allow significant improvements in system performances: in practice, the signal-to-noise ratio cannot be increased in standard detection schemes, both direct and coherent, by squeezing either the signal (because of propagation losses) or by the local oscillator. On the contrary, a significant improvement can be obtained in interferometric measurements if squeezed vacuum is coupled into the normally unused beamsplitter port.