Weak Measurements on Optical Systems

Dhara, Sayandip (2016) Weak Measurements on Optical Systems. Masters thesis, Indian Institute of Science Education and Research Kolkata.

PDF (MS dissertation of Sayandip Dhara (11MS016)) Thesis_Sayandip(11MS016).pdf - Submitted Version Restricted to Repository staff only Download (2MB)

Abstract

The spatial and the angular variants of the Imbert-Federov (IF) beam shifts and the angular Goos-Hänchen (GH) shift contribute in a complex interrelated way to the resultant beam shift in partial reflection at planar dielectric interfaces. Here, we show that the two variants of the IF effects can be decoupled and separately observed by weak value amplification and subsequent conversion of spatial to angular nature of the beam shifts using appropriate pre and post-selection of polarization states. Such optimized weak measurement schemes also enable one to nullify one effect (either the GH or the IF) and exclusively observe the other. We experimentally demonstrate this and illustrate various other intriguing manifestations of optimized weak measurements in elliptical and / or linear polarization basis. We also present a Poincare sphere based analysis on conversion / retention of the angular or spatial nature of the shifts with pre and post-selection of states in weak measurement. In another separate experiment we set up a Mach-Zender interferometer with the weak measurement scheme for partial reflection in one hand of the interferometer to observe the effect of the geometric phase gradient at the time of weak measurement and interpret the effect as an effective rotation of the interference fringe pattern.

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