We propose a unique application of the photonic spin Hall effect for ultrasensitive detection of the ion concentration in solution. By incorporating the quantum weak measurement, the photonic spin-Hall shift acts as the measurement pointer and the optical rotation of solution in the magnetic field acts as the postselection state. The optical rotation is related to the Faraday effect, which is sensitive to the ion concentration of the solution. The high measurement resolution with 1.4×10−4 degree for the optical rotation angle is achieved, which outperforms the standard polarimeter. Furthermore, the high resolution with 2×10−5mol/ml for the ion concentration is obtained due to the weak-value amplification in the quantum weak measurement. In our scheme, the ion concentration is real-time detected by the amplified spin-Hall shift and thereby provides possible applications in biochemical sensing and water-quality monitoring.
In recent decades, optical analog computing has attracted considerable interest in image processing and optical engineering. However, the optical analog computing system composed of traditional optical devices is bulky and difficult to integrate in practical applications. Here, we propose a method for inversely designing Pancharatnam–Berry phase metasurfaces based on specified optical computing. Derived from the evolution of the Pancharatnam–Berry phase on the Poincaré sphere, the special relationship between local optical axis structure and phase can be obtained. On this basis, we inversely design several metasurfaces and applied them into optical analog computing as well as all-optical image edge detection.
The phase and polarization of electromagnetic waves can be conveniently manipulated by the dynamic phase and geometric phase elements. Here, we propose a compact optical integration of dynamic phase and geometric phase to generate arbitrary vector vortex beams on a hybrid-order Poincaré sphere. Two different technologies have been applied to integrate dynamic and geometric phase elements into a single glass plate to modulate the phase and polarization of light simultaneously. A spiral phase structure is made on one side of a glass substrate with optical lithography and a geometric phase metasurface structure is designed on the other side by femtosecond laser writing. The vector polarization is realized by the metasurface structure, while the vortex phase is generated by the spiral phase plate. Therefore, any desirable vector vortex beams on the hybrid-order Poincaré sphere can be generated. We believe that our scheme may have potential applications in future integrated optical devices for the generation of vector vortex beams due to its the high transmission efficiency and conversion efficiency.
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