Rotational Doppler Frequency Shift from Time‐Evolving High‐Order Pancharatnam–Berry Phase: A Metasurface Approach. Issue 6 (25th April 2021)

• Record Type: Journal Article
• Authors: Yue, Fuyong; Aadhi, A.; Piccoli, Riccardo; Aglieri, Vincenzo; Macaluso, Roberto; Toma, Andrea; Morandotti, Roberto; Razzari, Luca
• Is Part Of: Laser & photonics reviews. Volume 15:Issue 6(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-04-25
• Subjects: metasurfaces -- orbital angular momentum -- Pancharatnam–Berry phase -- rotational Doppler frequency shift; Lasers -- Periodicals; Photonics -- Periodicals; Lasers -- Périodiques; Photonique -- Périodiques; 621.36
• DOI: 10.1002/lpor.202000576
• Languages: English
• ISSNs: 1863-8880

Abstract

Abstract: The Doppler frequency shift of sound or electromagnetic waves has been widely investigated in many different contexts and, nowadays, represents a formidable tool in medicine, engineering, astrophysics, and optics. Such effect is commonly described in the framework of the universal energy‐momentum conservation law. In particular, the rotational Doppler effect has been recently demonstrated using light carrying orbital angular momentum. When a wave undergoes a cyclic adiabatic transformation of its Hamiltonian, it is known to acquire the so‐called Pancharatnam–Berry (PB) phase. In this work, an experimental evidence of the direct connection between the high‐order PB phase time evolution on the Poincaré sphere and the rotational Doppler frequency shift of light is provided. A metasurface operating at telecom wavelengths is employed to impose a total (spin and orbital) angular momentum (TAM) on the light wave, while two TAM converters ensure a closed cycle on the Poincaré sphere. By rotating one of the converters, a significant Doppler frequency shift is observed without variation of the output TAM. The proposed metasurface‐based approach offers new advanced ways to engineer the frequency content of light. Abstract : A time‐evolving high‐order Pancharatnam–Berry phase, related to the dynamic transformation of light's total angular momentum on the Poincaré sphere, allows achieving an amplified rotational Doppler frequency shift. In this work, a metasurface approach for obtaining such Doppler shift is demonstrated, which may open new avenues to tailor the spectral components of structured light sources.