Phase-resolving spin-wave microscopy using infrared strobe light

Abstract

Rapid developments in film-based hybrid magnonic systems call for probing magnetization dynamics at smaller scales, with both amplitude and phase information. Here the stroboscopic technique is promising, but popular spectroscopic wavelengths in or near the UV-visible range face challenges in coherent modulation at the same target frequency (often gigahertz). The authors demonstrate that an IR-wavelength (1550 nm) strobe can be used for spatial imaging of spin waves, by exploiting the Faraday and magneto-optical Kerr effects. Their setup probes a spin wave's wavefront and intensity simultaneously, while being compact enough for a tabletop system with optical-fiber components.