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.
We demonstrate a new method to detect the vortex beams carrying orbital angular momentum (OAM) by a sectorial screen. When the sectorial screen is illuminated with vortex beams, the far-field diffraction pattern can be used to define the modulus and sign of topological charges. The number of the petals denotes the number of topological charge. The direction of intensity pattern flip by 180° for a change in the sign of topological charge. The experimental results agree well with the simulated results.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.