In this paper, the authors discuss the optimization of the Fe(FM-layer)/Pt(NM-layer) for efficient THz emission considering the following points: the FM and NM layer thickness, the optical pump wavelength, the choice of the substrate, and the out-coupling efficiency to the free-space. To improve the out-coupling efficiency, we introduce antenna structures with various shape. It has been demonstrated that a well-designed antenna structure can enhance the THz emission efficiency by several times. In addition, the authors will report a magnetic-field bias modulation, with which the signal detection efficiency can be almost doubled.
In this paper, we demonstrate significant enhancement of electro-optic (EO) sampling signal in the detection of pulsed terahertz (THz) waves by using a technique we call “polarization filtering”.
In the EO sampling of pulsed THz waves, a linearly polarized probe optical pulse is phase-modulated by THz electric field through the linear EO effect and, as the result, it becomes slightly elliptically polarized after passing through the EO crystal. The phase-retardation of the probe optical pulse is then detected as an optical intensity modulation (EO signal), dI/I (the ratio of the intensity change, dI, and the original intensity, I) with an appropriate optical detection system.
In “polarization filtering,” the EO sampling signal, dI/I, is enhanced by suppressing the main polarization component of the probe beam, resulting in a reduced probe beam intensity I’ = b^2*I, after the interaction with THz field in the EO crystal. Since the intensity modulation, dI, also reduces to dI’= b*dI, as the result of the polarization filtering, the THz EO sampling signal is enhanced by a factor of 1/b: dI’/I’ =(1/b)*dI/I. This “polarization filtering” is applicable not only to the conventional ellipsometric EO sampling but also to the heterodyne EO sampling. Firstly, we explain the principle of the polarization filtering, and then show the results of the proof-of-principle experiment for the standard and the heterodyne EO sampling, respectively.
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.