on a dielectric substrate....Figure 2.2 Geometrical parameters of an elliptical lens.Figure 2.3 (a) Equivalent aperture on top of the elliptical lens antenna. (b...Figure 2.4 (a) Scheme of the critical angle calculation on an elliptical len...Figure 2.5 (a) Incident, reflected, and transmitted power density in a diele...Figure 2.6 Reference system for the evaluation of the far fields radiated by...Figure 2.7 (a) High transmission and high reflection region of a silicon mad...Figure 2.8 Parallel and perpendicular transmission coefficient for a lens ma...Figure 2.9 Synthesis of an elliptical lens from an extended hemispherical le...Figure 2.10 Sketch of the extended semi‐hemispherical lens antenna parameter...Figure 2.11 Directivity of an elliptical lens and an extended hemispherical ...Figure 2.12 Sketch of the silicon lens antenna fed by a leaky‐wave feed geom...Figure 2.13 Real and imaginary parts of the propagation constants klw of the...Figure 2.14 Input reflection coefficient of a waveguide loaded with a double...Figure 2.15 Sketch of the leaky‐wave feed with its main parameters. The red ...Figure 2.16 Amplitude and phase of the electric centered at a central freque...Figure 2.17 (a) Drawing of the basic parameters of the shallow lens antenna ...Figure 2.18 Optimum (a) taper angle θf and (b) lens thickness W as a fu...Figure 2.19 (a) The shallow lens of diameter D is defined by a corresponding...Figure 2.20 (a) Radius R and (b) height H of the lens as a function of the d...Figure 2.21 (a) Directivity and (b) Gaussicity achieved for the shallow lens...Figure 2.22 Reflection coefficient centered at a central frequency f for the...Figure 2.23 (a) Sketch of the membrane fabrication process that contains the...Figure 2.24 (a) Sketch of the fabrication process of the shallow silicon len...Figure 2.25 (a) Surface measured of the fabricated lens of D = 2.6 mm. The e...Figure 2.26 Photographs of different lens antenna prototypes fed by leaky‐wa...Figure 2.27 (a) Reflection and (b) transmission coefficient for a silicon le...2 Chapter 3Figure 3.1 (a) Power spectrum from commercial EDFA mode‐locked laser. (b) Ti...Figure 3.2 Optical fiber absorption vs wavelength.Figure 3.3 (a) Near‐band‐edge absorption coefficient of GaAs at room tempera...Figure 3.4 (a) Fractional absorption vs epitaxial thickness for a GaAs layer...Figure 3.5 Residual electron concentration (black squares) and resistivity (...Figure 3.6 (a) Conventional 1550‐nm p–i–n photodiode. (b) Conventional MSM b...Figure 3.7 Simulation results for p–i–n InGaAs/InP photodiode, showing trans...Figure 3.8 Simulation results for the lifetime‐limited transfer function, an...Figure 3.9 Comparison between spectral responsivities of 1550‐nm InGaAs MSM‐...Figure 3.10 (a) Energy diagram of an MSM electrode structure with low bias a...Figure 3.11 (a) Cross‐sectional view of photoconductor illuminated from the ...Figure 3.12 (a) Equivalent circuit model for a photoconductive switch. (b) P...Figure 3.13 (a) Reflectance (R), transmittance (T), and absorbance (A) of a ...Figure 3.14 Comparison between calibrated SPD detector and a commercial pyro...Figure 3.15 Equivalent THz input power for the output signal of Figure 3.14 ...Figure 3.16 Comparison between SPD detector and commercial pyroelectric dete...Figure 3.17 THz optical responsivity of QMC detector after cross‐calibration...Figure 3.18 (a) Spectrum of two frequency‐offset DFB lasers measured with OS...Figure 3.19 (a) SEM photograph of MSM photomixer is located in the gap betwe...Figure 3.20 (a) Antenna on a dielectric substrate showing the rays trapped b...Figure 3.21 (a) Sketch of a dipole antenna with a stepped impedance low pass...Figure 3.22 (a) Sketch of a log‐spiral AE. The antenna (grey) and the photom...Figure 3.23 (a) Electric lines of force between two coplanar electrodes on a...Figure 3.24 Schematic of a THz time‐domain spectroscopy (TDS) setup in trans...Figure 3.25 (a) Typical normalized pulse trace and corresponding normalized ...Figure 3.26 THz power and optical‐to‐THz conversion efficiency for state‐of‐...Figure 3.27 (a) conventional p–i–n photodiode with the i‐region made of InGa...Figure 3.28 Photocurrent transfer function for UTC‐PD device structure param...Figure 3.29 (a) UTC‐PD fabricated at the gap of a bow‐tie antenna. (b) Fully...Figure 3.30 Comparison of UTC‐PD (NTT) and HHI p–i–n photodiode THz power re...Figure 3.31 (a) Schematic diagram of photoexcitation and recombination in an...Figure 3.32 Near‐infrared absorption spectrum
