Fig 2 - uploaded by Xinke Wang
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(Color online) (a) Normalized transmitted THz peak amplitudes (open squares and circles) on X and Y axes as rotating the WG and theoretical results (solid red and green lines) calculated by using Eqs. (7) and (8). (b) Relative changes in the measured THz polarization angle (open triangles) for rotations of the WG by 1° steps from 0° to 10° (solid pink line).
Contexts in source publication
Context 1
... maximum amplitude of the THz signal in the time domain is measured by the imaging system, and all pixels are integrated to build a curve as is changing. Two po- larization components of the THz signal are recorded in steps of 10° from 0° to 180°. The normalized plots and the- oretical results calculated by using Eqs. (7) and (8) are shown in Fig. 2(a). The rectangular open dot and red line are the experimental and theoretical values of E x , and the circular open dot and green line are those of E y . Measured THz amplitudes are well coincident with the calculated results. The phenomenon exhibits two points: first, the feasibility of the measurement method is demonstrated, which can ...
Context 2
... further estimate the relative sensitivity of the imag- ing system to the variation of the THz polarization angle, is adjusted from 0° to 10° in steps of 1°, and the THz polarization angle is calculated as meas = arctanE y / E x . The measured value (trigonal open dot) and the value of (pink line) are shown in Fig. 2(b). The maximum devia- tion of the measured result meas from the real value is 0.35°. Therefore, the minimum detectable change in the polarization angle should be less than 0.5°. There are sev- eral reasons for the ...
Context 3
... by virtue of Eq. (5). Figure 3(a) shows the THz temporal signals in the air in which the difference between the peak amplitudes of the two polarization components is very obvious. Their ratio is 50:1, which also indicates that the polarization of the incident THz waves is well horizontally linear and agrees with the measurement results in Fig. 2. Figures 3(b) and 3(c) are the transmitted THz signals from a quartz glass and a common glass. Although the differences of ampli- tudes and time shifts of these signals are very obvious due to these materials' different absorptions, refractive indices, and thicknesses, the ratios of their two polariza- tion components hardly change. Because these ...
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Citations
A wavelength de-multiplexing metasurface hologram composed of subwavelength metallic antennas is designed and demonstrated experimentally in the terahertz (THz) regime. Different character patterns are generated at the separated working frequencies 0.50 THz and 0.63 THz which determine a narrow frequency bandwidth of 130 GHz. The two working frequencies are around the central resonance frequency of the antennas where antennas behave strong wavefront modulation. Each antenna is fully utilized to control the wavefront of the metasurface at different frequencies by an optimization algorithm. The results demonstrate a candidate way to design multi-colors optical display elements.
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We have developed a real-time terahertz time-domain polarization analyzer by using 80-MHz repetition-rate femtosecond laser pulses. Our technique is based on the spinning electro-optic sensor method, which we recently proposed and demonstrated by using a regenerative amplifier laser system; here we improve the detection scheme in order to be able to use it with a femtosecond laser oscillator with laser pulses of a much higher repetition rate. This improvement brings great advantages for realizing broadband, compact and stable real-time terahertz time-domain polarization measurement systems for scientific and industrial applications.
Three dimensional information of the Gouy phase shift in a converging spherical terahertz (THz) beam is directly observed by using a THz balanced electro-optic holographic imaging system. The major properties of the Gouy phase shift are presented, including the longitudinal and transverse distributions, relationships with the frequency and the f-number, influence on the THz polarization. The imaging technique supplies an accurate and comprehensive measurement method for observing and understanding the Gouy phase shift.
We present a practicable way to take advantage of the spectral information contained in a broadband terahertz pulse for the determination of birefringence and orientation of the optical axis in a glass fiber reinforced polymer with a single measurement. Our setup employs circularly polarized terahertz waves and a polarization-sensitive detector to measure both components of the electromagnetic field simultaneously. The anisotropic optical parameters are obtained from an analysis of the phase and frequency resolved components of the terahertz field. This method shows a high tolerance against the skew of the detection axes and is also independent of a reference measurement.
