Phase-sensitive amplification for imaging resolution improvement and plasma interferometry
Abstract
The Rayleigh criterion sets a classical limit on the resolution of optical imaging systems, which brings challenges in remote sensing of spatial information. According to the Rayleigh criterion, only a limited control of resolution can be accomplished by adjusting the optical wavelength or aperture diameter. The resolvability of optical imaging systems can also be represented in terms of the signal-to-noise ratio (SNR). The optical parametric amplier (OPA) is a common nonlinear device used in a variety of applications, such as imaging, quantum information, and ultrafast laser science. It has been shown that when the OPA is operated as a phase-sensitive amplifier (PSA), no quantum noise is added thus preserving the SNR. In this thesis, the hypothesis testing from the classical information theory has been applied to the problem of distinguishing distant point sources. It is numerically demonstrated that an improvement of resolution beyond the classical limit and SNR enhancement could be achieved by utilizing the PSA operated in spatial domain. Plasma diagnostics deducts information of important parameters (such as temperature, plasma density and confinement) in magnetic confinement fusion (MCF) reactions. Interferometer can be used to measure the refractive index of plasma which is correlated with the plasma density. A Mach-Zehnder type interferometer enhanced by the PSA is studied. It has been found that the effect of the PSA is to increase the minimum resolvable interference fringe shift caused by plasma density perturbation so that a better resolution of the interferogram can be obtained. This method may enable significant improvement in plasma density measurement.
Degree
M.S.E.
Advisors
Jovanovic, Purdue University.
Subject Area
Nuclear engineering|Optics
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