Fundamentals of Terahertz Devices and Applications

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 of the GaAs with embedded ErAs... Figure 3.33 (a) Average THz power vs bias voltage for a photoconductive swit... Figure 3.34 (a) I – V characteristics of a waveguide integrated photodiode and... Figure 3.35 (a) Schematic of a fiber‐coupled THz‐TDS system and (b) a contin... Figure 3.36 Mobile communications network architecture. Figure 3.37 Main photonic‐based signal generation concept techniques.Figure 3.38 Ultra‐broadband wireless link with photonic‐based carrier wave g...Figure 3.39 (a) Eye‐patterns of the received PRBS = 2 23–1 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= ω band (b) ω= 0 .Figure 4.5 Photomixing experiment AC/DC decoupling using a Bias‐T.Figure 4.6 Small signal Equivalent circuit at ω b.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 ( G L= 1/ R L) .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 V b= 3 V.Figure 4.24 Output power at f B= and V b= 3 V.Figure 4.25 Top view of a 6‐μm‐diameter photoconductor coupled to the impeda...Figure 4.26 SEM micrograph of an optical cavity LT‐GaAs photoconductor linke...Figure 4.27 Down conversion experimental‐set‐up.Figure 4.28 Conversion loss and (1/G0) 2as a function of the optical power (Figure 4.29 Design of the nanostructured contact. (a) Geometry of the metall...Figure 4.30 Fabrication of the PD. (a, b) Schematic cross section of the fab...Figure 4.31 (a)SEM image of UTC‐PD integrated with CPW, and (b) SEM image of...Figure 4.32 Experimental comparison of photoresponse of UTC‐PD devices and R...Figure 4.33 RF power generated at 300 GHz by various B‐type photodiodes for ...Figure 4.34 SEM picture of an equiangular spiral antenna.Figure 4.35 Geometry of the TEM‐HA (a). Geometry of the monopole configurati...Figure 4.36 SEM picture of a THz Horn antenna.Figure 4.37 E‐plane radiation patterns of the TEM‐HA: comparison between exp...Figure 4.38 Different probes technologies: GGB probes (Picoprobes for wafer‐...Figure 4.39 (a) Experimental setup for photomixing at wafer‐level. (b) Photo...Figure 4.40 Frequency response example of a UTC‐PD [19].Figure 4.41 Frequency response example of and device linearity.Figure 4.42 Example of free space UTC‐PD measurement using a Schottky quasi‐...

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...

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