Spatial modes of phase-sensitive parametric image amplifiers with circular and elliptical Gaussian pumps

Area of Science:

• Quantum optics
• Nonlinear optics
• Laser physics

Background:

• Optical parametric amplifiers (OPAs) are crucial for generating squeezed light.
• Understanding mode structures in OPAs is essential for optimizing squeezed light generation and applications.
• Previous studies often focused on simplified pump profiles, limiting applicability to general cases.

Purpose of the Study:

• To develop a method for determining the number and shapes of independently squeezed or amplified modes in a broadband optical parametric amplifier.
• To analyze these modes under the general condition of an elliptical Gaussian pump.
• To provide insights for enhancing squeezed light detection and designing distortion-free parametric image amplifiers.

Main Methods:

• Developing a theoretical method to analyze the mode structure of a travelling-wave, frequency- and polarization-degenerate optical parametric amplifier.
• Considering an elliptical Gaussian pump profile to account for general experimental conditions.
• Investigating the influence of pump focusing and spot size on the resulting mode shapes.

Main Results:

• For tightly focused pumps, a single squeezed mode with a Gaussian TEM(00) shape is observed.
• For larger pump spot sizes supporting multiple modes, the dominant amplified modes approximate Hermite- or Laguerre-Gaussian profiles.
• The study quantifies the number and shapes of independently squeezed/amplified modes as a function of pump parameters.

Conclusions:

• The developed method accurately predicts the mode structure in optical parametric amplifiers.
• The findings enable the generation of matched local oscillators for improved detection of high levels of squeezing.
• The results facilitate the design of advanced parametric image amplifiers with reduced optical distortion.