Narrowband signal generation by spintronic THz emitters

Abstract

We report a technique for generating narrowband, high-frequency electrical signals using spintronic terahertz emitters (STEs) integrated onto coplanar waveguides (CPWs). Conventional STE operation typically yields ultrashort, broadband pulses spanning tens of terahertz. Our method employs multiple STEs positioned at precisely defined intervals along the CPW to produce a burst like signal, where the inter-emitter spacing determines the time delay between pulses, thus the fundamental burst frequency, which theoretically can be tuned across the STE bandwidth. Meander-shaped CPW geometries are used to enable compact integration and uniform optical excitation. First test devices demonstrate electrical signals up to 30 GHz with a bandwidth of 4.7 GHz corresponding to a quality factor of 6.38.