Fundamentals of Terahertz Devices and Applications

An authoritative and comprehensive guide to the devices and applications of Terahertz technology

Terahertz (THz) technology relates to applications that span in frequency from a few hundred GHz to more than 1000 GHz. Fundamentals of Terahertz Devices and Applications offers a comprehensive review of the devices and applications of Terahertz technology. With contributions from a range of experts on the topic, this book contains in a single volume an inclusive review of THz devices for signal generation, detection and treatment.

Fundamentals of Terahertz Devices and Applications offers an exploration and addresses key categories and aspects of Terahertz Technology such as: sources, detectors, transmission, electronic considerations and applications, optical (photonic) considerations and applications. Worked examplesbased on the contributors extensive experience highlight the chapter material presented. The text is designed for use by novices and professionals who want a better understanding of device operation and use, and is suitable for instructional purposes This important book:

Dimitris Pavlidis is a Research Professor at Florida International University. He has been Professor of Electrical Engineering and Computer Science at the University of Michigan (UofM) from 1986 to 2004 and a Founding Member of UofMs first of its kind NASA THz Center in 1988. He served as Program Director in Electronics, Photonics and Magnetic Devices (EPMD) at the National Science Foundation. He received the decoration of "Palmes Académiques" in the order of Chevalier by the French Ministry of Education and Distinguished Educator Award of the IEEE/MTT-S and is an IEEE Life Fellow.

About the Editor

Acknowledgements [still to follow]

Chapter 1: Introduction to THz Technologies

Dimitris Pavlidis

Chapter 2: THz Antennas

Maria Alonso-delPino and Nuria Llombart Juan

Introduction

Elliptical Lens Antennas

2.1 Elliptical Lens Synthesis

2.2 Radiation of Elliptical Lenses

2.2.1 Transmission function T ̃(Q)

2.2.2 Spreading Factor S(Q)

2.2.3 Equivalent Current Distribution and Far-Field Calculation

2.2.4 Lens Reflection Efficiency

3. Extended Semi-Hemispherical lens antennas

3. 1 Radiation of extended semi-hemispherical lenses

4. Shallow Lenses excited by leaky wave /Fabry-Perot feeds

4.1.Analysis of the leaky-wave propagation constant

4.2 Primary fields radiated by a leaky-wave antenna feed on an infinite medium

4.3 Shallow-Lens geometry optimization

5. Fly-eye Antenna Array

5.1 Silicon DRIE micromachining process at submillimeter-wave frequencies

5.1.1 Fabrication of silicon lenses using DRIE

5.1.2 Surface Accuracy

5.2 Examples of fabricated antennas

Chapter 3: Photoconductive THz Sources Driven at 1550 nm

E.R. Brown, G. Carpintero del Barrio, A. Rivera, D. Segovia-Vargas, B. Globisch, and A. Steiger

I. Introduction

Overview of THz Photoconductive Sources

Lasers and Fiber Optics

II. 1550-nm THz photoconductive sources

II.A. Epitaxial Materials

Bandgap Engineering

Low Temperature Growth

II.B. Device Types and Modes of Operation

II.C. Analysis of THz photoconductive sources

II.C.1. PC-Switch Analysis

II.C.2. Photomixer Analysis

II.C.2.a. p-i-n photodiode

II.C.2.b. MSM bulk photoconductor

II.D. Practical Issues

Contact Effects

Thermal Effects

Circuit Limitations

III. THz Metrology

Power Measurements

A Traceable Power Sensor

Exemplary THz Power Measurement Exercise

Other Sources of Error

Frequency Metrology

IV. THz Antenna Coupling

Fundamental Principles

Planar antennas on dielectric substrates

Input Impedance

ΔEIRP (increase in the EIRP of the transmitting antenna)

G/T or Aeff/T

Estimation of Power Coupling Factor

Exemplary THz Planar Antennas

Resonant antennas

Quick survey of self-complementary antennas

V. State-of-the-Art in 1550-nm Photoconductive Sources Error! Bookmark not defined.

1550-nm MSM Photoconductive Switches

Material and Device Design

THz Performance

1550-nm Photodiode CW (photomixer) Sources

Material and Device Design

THz Performance

VI. Alternative 1550-nm THz Photoconductive Sources Error! Bookmark not defined.

Fe-Doped InGaAs

ErAs Nanoparticles in GaAs: Extrinsic Photoconductivity

VII. System Applications Error! Bookmark not defined.

Comparison between pulsed and cw THz systems

Device aspects

Systems aspects

Wireless Communications

THz Spectroscopy

Time vs Frequency Domain Systems

Analysis of Frequency Domain Systems: Amplitude and Phase Modulation

Exercises

Chapter 4 : THz Photomixers

E. Peytavit, G. Ducournau, J-F. Lampin

1. Introduction

2. Elliptical Lens Antennas

2.1 Elliptical Lens Synthesis

2.2 Radiation of Elliptical Lenses

2.2.1 Transmission function TQ

2.2.2 Spreading Factor SQ

2.2.3 Equivalent Current Distribution and Far-Field Calculation

2.2.4 Lens Reflection Efficiency

3. Extended Semi-Hemispherical lens antennas

3. 1 Radiation of extended semi-hemispherical lenses

4. Shallow Lenses excited by leaky wave /Fabry-Perot feeds

4.1.Analysis of the leaky-wave propagation constant

4.2 Primary fields radiated by a leaky-wave antenna feed on an infinite medium

4.3 Shallow-Lens geometry optimization

5. Fly-eye Antenna Array

5.1 Silicon DRIE micromachining process at submillimeter-wave frequencies

5.1.1 Fabrication of silicon lenses using DRIE

5.1.2 Surface Accuracy

5.2 Examples of fabricated antennas

Chapter 5: Plasmonics-enhanced Photoconductive Terahertz Devices

Ping Keng Lu and Mona Jarrahi

Introduction

Photoconductive Antennas

Photoconductors for THz operation

Photoconductive THz emitters

Pulsed THz emitters

Continuous-wave THz emitters

Photoconductive THz Detectors

Common photoconductors and antennas for photoconductive THz devices

Plasmonics-enhanced photoconductive antennas

Fundamentals of plasmonics

Plasmonics for enhancing performance of photoconductive THz devices

Principles of plasmonic enhancement

Design considerations for plasmonic nanostructures

State-of-the-art plasmonics-enhanced photoconductive THz devices

Photoconductive THz devices with plasmonic contact electrodes

Large area plasmonic photoconductive nanoantenna arrays

Plasmonic photoconductive THz devices with optical nanocavities

Conclusion and Outlook

Chapter 6 : Terahertz Quantum Cascade Lasers

Roberto Paiella

1. Introduction

2. Fundamentals of Intersubband Transitions

3. Active Material Design

4. Optical Waveguides and Cavities

5. State-of-the-Art Performance and Limitations

6. Novel Materials Systems

6.1 III-Nitride Quantum Wells

6.2 SiGe Quantum Wells

7. Conclusion 

Chapter 7: Advanced Devices Using Two-Dimensional Layer Technology

Berardi Sensale-Rodriguez

7.1. Graphene-based THz Devices

7.1.1. THz Properties of graphene

7.1.2. How to simulate and model graphene?

7.1.3. Terahertz device applications of graphene

Modulators

- Broadband structures

- Electromagnetic-cavity integrated structures

- Graphene/metal -hybrid metamaterials

- Graphene/dielectric -hybrid metamaterials

- Active filters

- Phase modulation in graphene-based metamaterials

7.2. TMD based THz Devices

7.3. Applications

Chapter 8: THz Plasma Field Effect Transistor Detectors

Naznin Akter, Nezih Pala, Wojcieech Knap, Michael Shur

 Introduction

Field effect transistors (fets) and thz plasma oscillations

2.1. Dispersion of plasma waves in fets

2.2. THz detection by an fet

Resonant detection

Broadband detection

THz detectors based on silicon fets

Terahertz detection by graphene plasmonic fets

Terahertz detection in black-phosphorus nano-transistors

Diamond plasmonic thz detectors

Conclusion

[Was Chapter 13] Chapter 9: Signal Generation by Diode Multiplication

Alain Maestrini and Jose Siles

1 Introduction 3

2 Bridging the microwave to photonics gap with terahertz frequency multipliers 3

3 A practical approach to the design of frequency multipliers 5

3.1 Frequency multiplier versus comb generator 5

3.2 Frequency multiplier ideal matching network and ideal device performance 6

3.3 Symmetry at device level versus symmetry at circuit level 7

3.4 Classic balanced frequency doublers 8

3.4.1 General circuit description 8

3.4.2 Necessary condition to balance the circuit 9

3.5 Balanced frequency triplers with an anti-parallel pair of diodes 11

3.6 Multi-anode frequency triplers in a virtual loop configuration 12

3.6.1 General circuit description 12

3.6.2 Necessary condition to balance the circuit 14

3.7 Multiplier design optimization 15

3.7.1 General design methodology 16

3.7.2 Non-linear modeling of the Schottky diode barrier 22

3.7.3 3D modeling of the extrinsic structure of the diodes 23

3.7.4 Modeling and optimization of the diode cell 24

3.7.5 Input and output matching circuits. 26

4 Technology of THz diode frequency multipliers 26

4.1 From Whisker-contacted diodes to Planar Discrete Diodes 26

4.2 Semi-monolithic frequency multipliers at THz frequencies 27

4.3 THz local oscillators for the Heterodyne Instrument of Herschel Space Observatory 29

4.4 First 2.7THz multiplier chain with more than 10µW of power at room temperature 32

4.5 High power 1.6THz frequency multiplied source for future 4.75THz local oscillator 34

5 Power-combining at sub-millimeter wavelength 36

5.1 In-phase power combining 36

5.1.1 First in-phase power-combined submillimeter-wave frequency multiplier 37

5.1.2 In-phase power combining at 900GHz 38

5.1.3 In-phase power-combined balanced doublers 40

5.2 In-channel power combining 41

5.3 Advanced on-chip power combining 42

5.3.1 High power 490-560GHz frequency tripler 43

5.3.2 Dual-Output 550 GHz Frequency Tripler 43

5.3.3 High-power quad channel 165-195GHz frequency doubler 44

6 Conclusions and perspectives 46

7 References 46

8 Problems 52

[WasChapter 9] Chapter 10: GaN Multipliers

Chong Jin and Dimitris Pavlidis

1 Introduction

1.1 Frequency Multipliers

1.2 Properties of Nitride Materials

1.3 Motivation and Challenges

2 Theoretical Considerations of GaN Schottky Diode Design

2.1 Analysis by Analytical Equations

2.1.1 Nonlinearity and Harmonic Generation

2.1.2 Nonlinearity of Ideal Schottky Diode

2.1.3 Series Resistance

2.2 Analysis by numeric simulation

2.2.1 Introduction of Semiconductor Device Numerical Simulation

2.2.2 Parameters for GaN Based Device Simulation

2.2.3 Simulation Results

Device Structure

Breakdown voltage

I-V characteristics

Series resistance

C-V characteristics

Time Domain Transient Analysis

2.3 Conclusions on Theoretical Considerations of GaN Schottky Diode Design

3 Fabrication Process of GaN Schottky Diodes

3.1 Fabrication Process

3.2 Etching

3.3 Metallization

3.3.1 Ohmic Contacts on GaN

3.3.2 Schottky Contacts on GaN

Analysis of Schottky contact characteristics

Oxygen plasma before Schottky metallization

3.4 Bridge Interconnects

Dielectric Bridge

Optical Air-bridge

E-Beam Air-bridge

3.5 Conclusion on Fabrication Process of GaN Schottky Diodes

Small-signal High Frequency Characterization of GaN Schottky

4 Diodes

4.1 Current-Voltage Characteristics

4.2 Small-signal Characterization and Equivalent Circuit Modeling

Step 1. Parasitic elements

Step 2. Junction Capacitance

Step 3. Optimization

Summary

4.3 Results

4.4 Conclusion

5 Large-Signal On-wafer Characterization

5.1 Characterization Approach

5.2 Large signal measurements of GaN Schottky diodes

5.2.1 LSNA with 50 Ω load

Time domain waveforms

Power handling characteristics

5.3 LSNA with harmonic loadpull

5.4 Conclusion

6 GaN Diode Implementation for Signal generation

6.1 Large-signal modeling of GaN Schottky diodes

6.2 Frequency Doubler

7 Multiplier Considerations for Optimum Performance

Exercises 

[Was Chapter 10] Chapter 11: THz Resonant Tunneling Devices

Masahiro Asada and Safumi Suzuki

10.1 Introduction

10.2 Basic structure and operation of RTD

10.2.1 Basic operation of RTD

10.2.2 Principle of oscillation

10.2.3 Effect of electron delay time

10.3 Structure and oscillation characteristics of fabricated RTD oscillators

10.3.1 Actual structure of RTD oscillators

10.3.2 High-frequency oscillation

10.3.3 High-output power oscillation

10.4 Control of oscillation spectrum and frequency

10.4.1 Oscillation spectrum and phase-locked loop

10.4.2 Frequency-tunable oscillators

10.5 Targeted applications

10.5.1 High-speed wireless communications

10.5.2 Spectroscopy

10.5.3 Other applications and expected future development

[Was Chapter 11] Chapter 12: Wireless communications in the THz range

G. Ducournau, T. Nagatsuma

11.1 Evolution of telecoms towards THz

11.1.1 Brief historic

11.1.2 Data rate evolution

11.1.3 THz waves: propagation, advantages and disadvantages

11.1.4 Frequency bands

11.1.5 Potential scenarios

11.1.6 Comparison between FSO and THz

11.2 THz technologies: transmitters, receivers and basic architecture

11.2.1 THz sources

11.2.2 THz receivers

11.2.3 Basic architecture of the transmission system

11.3 Devices/function examples for T-ray coms

11.3.1 Photomixing techniques for THz coms

11.3.2 THz modulated signals enabled by photomixing

11.3.3 Other techniques for the generation of modulated THz signals

11.3.4 Integration, interconnections and antennas

11.3.4.1 Integration

11.3.4.2 Antennas

11.4 THz links

11.4.1 Modulations and key Indicators of a THz Communication Link

11.4.2 State of the art of THz links

11.4.2.1 First systems

11.4.2.2 Photonics-based demos

11.4.2.3 Electronic-based demos

11.4.2.4 Beyond 100 GHz high power amplification

11.4.2.5 Table of reported systems

11.5 Towards normalisation of 100G links in the THz range

11.6 Conclusion Error! Bookmark not defined.

11. 7 Acronyms

11.8 References

11.9 Exercice : link budget of a THz link

[Was Chapter 12] Chapter 13: THz Applications: Devices to Space System

Imran Mehdi

12.1 INTRODUCTION

12.1.1 Why is THz technology important for space science?

12.1.2 Fundamentals of THz Spectroscopy

12.1.3 THz Technology for Space Exploration

12.2 THz HETERODYNE RECEIVERS

12.2.1 Local Oscillators

12.2.1.1 Frequency Multiplied Chains

12.2.2 Mixers

12.2.2.1 Room Temperature Schottky Diode Mixers

12.2.2.2 SIS Mixer Technology

12.2.2.3 Hot Electron Bolometric (HEB) Mixers

12.2.2.4 State-of-the-Art Receiver Sensitivities

12.3 THZ SPACE APPLICATIONS

12.3.1 Planetary Science: The Case for Miniaturization

12.3.2 Astrophysics: The Case for THz Array Receivers

12.3.3 Earth Science: The Case for Active THz Systems

12.4 SUMMARY AND FUTURE TRENDS

12.5 REFERENCES AND CITATIONS

12.6 PROBLEMS

Index

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