at bit rate BR = 1...Figure 3.40 (a) Performance of 1550‐nm fiber‐coupled time‐domain spectromete...Figure 3.41 (a) THz pulse and (b) associated spectrum, for state‐of‐the‐art ...Figure 3.42 (a) Performance of 1550‐nm fiber‐coupled frequency‐domain spectr...Figure 3.43 (a) Block diagram of 780‐nm FDS spectrometer having a single‐wav...Figure 3.44 (a) Block diagram of 1550‐nm fiber‐based wavelength‐selective ph...
3 Chapter 4Figure 4.1 THz generation by photomixing.Figure 4.2 Photomixing in a photoconductor.Figure 4.3 Electrical model of a photoconductor coupled to a load admittance...Figure 4.4 (a) Electrical circuit at ω = ωb and (b) ω = 0.Figure 4.5 Photomixing experiment AC/DC decoupling using a Bias‐T.Figure 4.6 Small signal Equivalent circuit at ωb.Figure 4.7 Schematic band diagram of a p–i–n photodiode.Figure 4.8 Schematic band diagram of a UTC photodiode.Figure 4.9 Electric model of a UTC photodiode.Figure 4.10 Equivalent circuit of an UTC photodiode at ω (GL = 1/RL).Figure 4.11 Heterodyne mixing in a photoconductor illuminated by an optical ...Figure 4.12 SEM picture of an ultrafast photoconductor based on interdigitat...Figure 4.13 LT‐GaAs planar photoconductor.Figure 4.14 Refracting facet UTC photodiode.Figure 4.15 TEM horn UTC photodiode.Figure 4.16 Waveguide UTC photodiode coupled to a planar antenna.Figure 4.17 LT GaAs optical cavity photoconductor.Figure 4.18 Calculated optical quantum efficiency versus active layer thickn...Figure 4.19 Experimental set‐up aimed at photoresponse measurement.Figure 4.20 Theoretical (solid line) and experimental (in squares) photoresp...Figure 4.21 Optical cavity LT‐GaAs photoconductor.Figure 4.22 Experimental set‐up. ECLD, external cavity laser diode; SOA, sem...Figure 4.23 Photocurrent as a function of optical power Vb = 3 V.Figure 4.24 Output power at fB =
4 Chapter 5Figure 5.1 Band to band absorption of a photon in a semiconductor, creating ...Figure 5.2 (a) Schematic of a PCA in operation. (b) Equivalent circuit model...Figure 5.3 Comparison between a short‐carrier‐lifetime and a long‐carrier‐li...Figure 5.4 Equivalent circuit model of a PCA‐based THz detector.Figure 5.5 Surface plasmon dispersion relation, showing that surface plasmon...Figure 5.6 Illustrations for (a) conventional and (b) plasmonic PCAs based o...Figure 5.7 Finite element simulation of the conventional photoconductor and ...Figure 5.8 (a) SEM images of the conventional (left) and plasmonic (right) P...Figure 5.9 (a) THz waveform measured by a conventional (red) and plasmonic (...Figure 5.10 PCAs with plasmonic light concentrators. (a) Device illustration...Figure 5.11 Pulsed THz generation and detection using PCAs with plasmonic co...Figure 5.12 CW THz generation using PCAs with plasmonic contact electrodes. ...Figure 5.13 (a) Device structure and SEM images of a large‐area plasmonic ph...Figure 5.14 Device structure and SEM images of a large‐area plasmonic photoc...Figure 5.15 Plasmonic PCAs with optical nanocavities. (a) Device schematic o...
5 Chapter 6Figure 6.1 (a) Conduction‐band lineup of a generic semiconductor QW and squa...Figure 6.2 Conduction‐band diagram of a representative bound‐to‐bound QC gai...Figure 6.3 Conduction‐band diagram of a representative superlattice QC gain ...Figure 6.4 Conduction‐band diagram of a representative resonant‐phonon THz Q...Figure 6.5 Real part of the dielectric constant ε and mode intensity pr...Figure 6.6 Metal–metal corrugated ridge DFB THz QC laser.Figure 6.7 Voltage‐tunable cw emission spectra measured at 15 K with the low...Figure 6.8 Temperature‐dependent LIV characteristics measured with the highe...Figure 6.9 (a) Schematic illustration of ISB relaxation between two QW subba...Figure 6.10 Dispersion of light in a polar crystal in the spectral vicinity ...Figure 6.11 Conduction‐band diagram of a resonant‐phonon THz QC gain medium ...Figure 6.12 (a) Photocurrent spectrum of a double‐step III‐nitride ISB photo...Figure 6.13 (a) Valence‐band lineup of the SiGe/Si QC active material of Dem...Figure 6.14 (a) Fabrication process developed in [81, 82] for the formation ...Figure 6.15 Conduction‐band lineup and squared envelope functions of the rel...
6 Chapter 7Figure 7.1 (a) Band structure of graphene and sketch of the possible optical...Figure 7.2 (a) Definition of parameters in a generic structure with N conduc...Figure 7.3 (a) Schematic of the reconfigurable region in a terahertz modulat...Figure 7.4 Experimental results in broadband modulator structures. (a) Trans...Figure 7.5 Structure of an electromagnetic‐cavity integrated graphene electr...Figure 7.6 Experimental results on electromagnetic‐cavity integrated modulat...Figure 7.7 Example work on graphene/metal‐hybrid metamaterial structures so ...Figure 7.8 Summary of results on graphene/meta‐hybrid metamaterials when cha...Figure 7.9 Graphene/metal‐hybrid metamaterials: transmission line equivalent...Figure 7.10 (a) Sketch of the analyzed graphene‐dielectric integrated metasu...Figure 7.11 Two proposed ways in which to alter the sensitivity of terahertz...Figure 7.12 Graphene‐based active terahertz filters. (a) Sketch of the devic...Figure 7.13 Simulated (a) and measured (b) terahertz transmittance versus fr...Figure 7.14 Deep‐subwavelength metamaterial phase modulators. (a) Sketch of ...Figure 7.15 Geometrical trade‐offs in deeply‐scaled metamaterials. The metal...Figure 7.16 (a) Schematic of a MoS2/metal‐hybrid metamaterial structure. The...Figure 7.17 Experimental result in MoS2/metal hybrid metamaterials. (a) Meas...Figure 7.18 Ultrafast dynamics in WSe2 thin films. (a) OPTP measurements of ...Figure 7.19 (a) Schematic and (b) optical image of a graphene reflection‐mod...Figure 7.20 Principle of the imaging experiment using graphene‐modulator arr...Figure 7.21 (a) Map of “pixelated illumination” without an object: ΔRi0
7 Chapter 8Figure 8.1 Plasma wave frequencies for different sample geometries. (a) Gate...Figure 8.2 Schematics of a FET as a THz detector (a); and the equivalent cir...Figure 8.3 Schematic representation of the plasma waves in different regimes...Figure 8.4 (a) Detected drain‐source signal as a function of the gate voltag...Figure 8.5 (a) Measured (squares) and calculated 0.2 THz drain response of 2...Figure 8.6 (a) Schematic illustration of FinFET device structure (the drain ...Figure 8.7 (a) 32 × 32 FPA chip complete die micrograph (2.9 × 2.9 mm2) and ...Figure 8.8 (a) Top‐view illustration of a typical graphene micro‐ribbon arra...Figure 8.9 (a) Room temperature responsivity as a function of the gate bias ...Figure 8.10 (a) Schematics of the encapsulated BLG FET (top) and optical pho...Figure 8.11 (a) BP atoms are arranged in puckered honeycomb layers bounded t...Figure 8.12 Scanning electron microscope (SEM) images of the top‐gated FETs ...Figure 8.13 (a) Plasma velocity in diamond 2DHG as a function of hole effect...Figure 8.14 DC voltage response to the THz voltage of the 0.01 V amplitude a...
8 Chapter 9Figure 9.1 State‐of‐the‐art of frequency multiplier sources at room temperat...Figure 9.2 Frequency multiplier vs comb‐generator.Figure 9.3 Frequency multiplier ideal matching network and optimization.Figure 9.4 JPL 400 GHz four‐anode doubler with substrate‐less technology (de...Figure 9.5 LERMA‐C2N demonstration model of the 600 GHz two‐anode balanced d...Figure 9.6 Currents and electrical fields in the vicinity of the diodes of a...Figure 9.7 Schematics of a sub‐millimeter wave frequency tripler using an an...Figure 9.8 Picture of a four‐anode 900 GHz balanced tripler (designed