We calculate amplitude squeezing spectra for the light from a variety of conventionally pumped three- and four-level lasers. Hence we extend a recent prediction that a certain three-level laser can generate nonclassical light without the need for rigged pumping.
It has recently been discovered that the quantum theory of the laser allows conventional lasers to produce squeezed light.1-3 The physics of this squeezing is uncomplicated and robust. It relies on the fact that a sequence of Poissonian transitions having the same total mean transition time as a single Poissonian process have less time variance than the single process. Hence the sequence of transitions has sub-Poissonian time statistics. This can be transformed into sub-Poissonian laser pumping and hence into sub-Poissonian and quadrature squeezed laser light. We will discuss how this theory can be put into practice. The effects of mode structure and inefficiences will be assessed. Candidate lasers and progress towards their experimental realization will be discussed.
The generation of nonclassical light has recently received a great deal of attention because three forms of it have now been observed in the laboratory: antibunched light, photon-number-squeezed (or sub-Poisson) light, and quadrature-squeezed light. These characteristics may, but need not, accompany each other in any given light source. Nonclassical light has been produced in experiments using resonance fluorescence, the Franck-Hertz effect, parametric interact ions, and semiconductor light sources. It is likely to be useful in providing new insights in various physical and biological processes, and in applications such as lightwave communications. Some of the characteristics, methods of generation, and expected uses of squeezed light will be addressed.