Spatial Squeezing, Entanglement, and Solitonic EPR Sources in Chi(2) Minicavities

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

This award is in support of studies of spatial squeezing in optical second harmonic generation. Practical sources of radiation fields exhibiting time domain quadrature squeezing, twin-beam correlations, and other quantum optical phenomena were developed in the 1980's and 1990's. We will investigate spatial aspects of non-classical light generated by optical second harmonic generation. Spatial squeezing has been theoretically predicted to appear in second harmonic generation as a sub-critical precursor of transverse modulational instability. We are working on a series of experiments aimed at observing both classical patterns above the modulational instability threshold, as well as the below threshold quantum signatures. The experimental work uses singly and doubly resonant optical cavities driven by continuous wave and nanosecond pulsed near infrared sources. Detailed measurements will be made of the degree of squeezing as a function of cavity tuning, phase mismatch, and spatial wavenumber. We will also work with parameter regimes where the second harmonic field that is internally generated in the optical cavity directly drives the competing process of optical parametric oscillation. This so-called internally pumped optical parametric oscillator (IPOPO) has the unique feature that the down converted parametric fields that display non-classical correlations are generated at the same wavelength as the incident pump beam using a single nonlinear crystal. This eliminates the need for separate frequency doubling stages, which reduces device complexity, and greatly facilitates frequency tuning of the combined process. The resulting quadrature squeezed fields will be used for measurements of spatial displacement with sub shot-noise resolution. In parallel with the experimental work we will perform theoretical calculations of the spectrum of spatial squeezing for the different possible cavity configurations. In particular a search will be made for parameter regimes that provide continuous variable entanglement of spatially modulated fields in the IPOPO device. The educational component of the project will include training graduate students in modern experimental and theoretical techniques that enable applications of non-classical light fields.