/2, unless the focusing is very weak. The use
of a second DOPA for generating a local oscillator beam that is
matched to the squeezed field is also investigated. In this case,
squeezing is limited only by the available pump power.
This paper investigates the generation of quadrature-squeezed states
of light using a degenerate optical parametric amplifier (DOPA) that
is pumped by a focused Gaussian beam. The formulation that is
presented facilitates the calculation of squeezing for an arbitrary
local oscillator beam. This formulation also establishes a formal
equivalence between the classical parametric gain and the measured
level of squeezing. The maximum squeezing that can be achieved using a
Gaussian-beam local oscillator is determined to be limited to 13.4 dB,
as a consequence of gain-induced diffraction. The phase lag of the
maximally squeezed quadrature is shown to be significantly different
from the plane-wave theoretic value of /2, unless the focusing is very weak. The use
of a second DOPA for generating a local oscillator beam that is
matched to the squeezed field is also investigated. In this case,
squeezing is limited only by the available pump power.
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