Spintronic terahertz emitters with unidirectional radiation

Spintronic terahertz emitters (STEs) with the feature of high performance and low cost have been a hot spot in the field of terahertz sources. However, little attention has been paid to the control and modulation of the THz waves generated by the STE. In this paper, we propose a unidirectional spintronic terahertz emitter (USTE) integrated a common STE with a metal grating. The dyadic Green’s function method and finite element method are adopted to survey the characteristics of the USTE. Simulation results show that the metal grating has a transmission larger than 97% in the optical band. Meanwhile it also has a higher reflectivity larger than 99% in the THz band. As a result, the USTE has a unidirectional THz emission along the direction of the pump beam with a larger than 4-fold enhancement in intensity. Besides, the USTE has the capability of tuning the central frequency. We think that this USTE can be used in THz wireless communications and holographic imaging, especially in the field of THz bio-sensing, which needs some resonance frequencies to sense.