Squeezing energy locally out of the vacuum

A one-dimensional box partly filled with a dielectric medium, E > 1, is considered as a model of a laser. The requirement that initially the electromagnetic energy be localized as much as possible in a finite region of the box is satisfied if each normal mode of the field is prepared in a squeezed state. In these states the expectation value of the energy density integrated over a specific volume is smaller than compared to its value in the quantum-mechanical vacuum. In principle, this result can be used to increase the force acting on a perfectly conducting plate in a Casimir-type situation