The focus is given on millimeter/micro wave signal generation based on external modulators. The working principle and modulation characteristics of Mach-Zehnder modulators (MZM) are introduced. Literature review is presented on generating millimeter/micro wave signals with 4-, 6-, and 8-times frequency multiplication based on cascaded MZMs or dual-parallel MZMs (DPMZMs). A novel scheme to optically generate a microwave signal with 10-times frequency multiplication is proposed. The proposed scheme is based on two DPMZMs and a polarizer. It does not require electrical phase shifters with specified degrees, which are needed in the conventional 10 times frequency multiplication structure. Simulation is conducted to evaluate the performance of the proposed scheme. When a 1 GHz RF drive signal turns into two DPMZMs with a 35 dB extinction ratio, the proposed 10 times frequency multiplier with an optical sideband suppression ratio (OSSR) higher than 25 dB can be obtained. A 10 GHz mm-wave with an RF spurious suppression ratio (RFSSR) over 16 dB is generated. A frequency quadrupling scheme based on a DPMZM is experimentally demonstrated. With a 3 GHz RF drive signal, an OSSR higher than 8 dB is obtained and a 12 GHz mm-wave is generated with an RFSSR over 11 dB.
Table of Contents
1. Introduction
1.1 Microwave photonics
1.1.1 Background
1.1.2 Microwave photonic link
1.2 Advantages
1.3 Research fields and applications
1.4 Conclusion
2. Optical generation of micro/millimeter wave technology
2.1 Background
2.2 Optical Heterodyne
2.2.1 Optical Injection Locking
2.2.2 Optical Phase Lock Loop
2.2.3 Optical injection phase Locking Loop
2.3 Opto-electronic Oscillator
2.4 External modulation method
3. Optical external modulator
3.1 Electro-optic effect
3.2 Mach-Zehender Modulator
3.3 Dual Drive MZM
3.4 Modulation theory
3.4.1 Double-sideband (DSB) modulation
3.4.2 Single-sideband (SSB) modulation
3.4.3 Optical carrier suppressed double-sideband (OCS-DSB) modulation
3.4.4 Odd-order optical sideband modulation
3.4.5 Even-order optical sideband modulation
3.4.6 Linear modulation
3.5 Conclusion
4. Literature review
4.1 Introduction
4.2 Microwave generation with frequency doubled based on one biased MZM
4.2.1 System structure and principle
4.2.2 Simulation
4.2.3 Experiment and conclusion
4.3 Microwave signal generation based on two cascaded MZMs
4.3.1 Frequency quadrupling scheme
4.3.2 Frequency sextupling scheme
4.3.3 Frequency octupling scheme
4.3.4 Summary
4.4 Microwave signal generation based on a Dual-parallel Mach-Zehnder Modulator
4.4.1 System structure and principle
4.4.2 Frequency quadrupling scheme
4.4.3 Frequency sextupling scheme
4.4.4 Frequency octupling scheme
4.4.5 Frequency 12-tupler scheme
4.4.6 Conclusion
4.5 Frequency octupling scheme based on two parallel DPMZMs
4.5.1 The system structure and principle
4.5.2 Simulation
4.5.3 Conclusion
4.6 Frequency 10-tupling scheme
4.6.1 Frequency 10-tupling based on cascaded MZMs
4.6.2 Frequency 10-tupling based on DPMZM and SBS
4.6.3 Conclusion
5. Simulation for the MZM or DPMZM in VPI
5.1 Simulation for MZM
5.1.1 Even-order optical sidebands
5.1.2 Odd-order optical sidebands modulation
5.1.3 Linear optical sidebands
5.2 How to suppress the first-order optical sidebands
5.2.1 Modulation theory
5.2.2 Simulation
5.3 Photonic frequency multiplication microwave generation based on DPMZM
5.3.1 Modulation theory
5.3.2 Simulation analysis
5.4 Generation of single sidebands based on one MZM and one PM without a coupler
5.4.1 Basic principle
5.4.2 Simulation
5.4.3 Conclusion
6. Microwave signal generation based on two parallel DP-MZMs
6.1 A scheme for generating frequency 8-tupling microwave based on two DPMZMs
6.1.1 Basic principle
6.1.2 Simulation for Frequency 8-tupling microwave generation
6.2 Frequency 12-tupling microwave generation scheme based on two parallel DP-MZMs
6.2.1 Basic principle
6.2.2 Simulation for Frequency 12-tupling microwave generation
7. New schemes for frequency 10-tupling microwave generation
7.1 Frequency 10-tupling microwave generation scheme based on one DP-MZM.
7.1.1 Basic principle
7.1.2 Simulation for Frequency 10-tupling microwave generation
7.2 Frequency 10-tupling microwave generation scheme based on two parallel DP-MZMs.
7.2.1 Basic principle
7.2.2 Simulation for Frequency 10-tupling microwave generation
7.3 Conclusion
8. Experiment
8.1 Validating modulation index
8.1.1 Principle
8.1.2 Simulations and experimental results
8.1.3 Conclusion
8.2 Generation of frequency-quadrupled microwave signals based on one DPMZM
8.2.1 Principle
8.2.2 Simulation structure
8.2.3 Experimental results
8.2.4 Conclusion
9. Conclusion and future work
9.1 Conclusion
9.2 Future work
10. References
Research Objectives and Themes
The primary research objective of this thesis is to investigate and develop methods for generating high-frequency, high-quality microwave signals using optical techniques, specifically by utilizing external modulators such as the Mach-Zehnder Modulator (MZM). The research addresses the "electronics bottleneck" by providing photonic-based solutions for millimeter/microwave signal generation that are stable, tunable, and capable of high-frequency multiplication.
- Photonic frequency multiplication microwave generation
- Application of external modulators (MZM, DPMZM)
- Simulation analysis using VPI and OptiSystem software
- Comparative review of frequency generation schemes
Extract from the book
Chapter 1 Introduction
Since the 1970s, with the rapid development of semiconductor lasers, high-speed photodetectors, erbium-doped fiber amplifiers, optical wavelength division multiplexing, integrated optics, optical fibers and other optical technologies, optical fiber communication has been developed rapidly and attracted more and more people’s attention and interest. Optical fiber communication has many advantages such as small volume, light weight, low loss, high bandwidth, no electromagnetic interference and ease to reuse (wavelength, polarization, space) and so on. At the same time, microwave technology has also developed swiftly. Microwave communication can be transmitted in any direction in space and be easily constructed and reconstructed to realize the interconnection of mobile devices.
However, with people’s demand for increasing information capacity and greater instantaneous bandwidth of a signal, more and more spectrum resources are occupied, which causes traditional wireless spectrum resources to fail to meet people’s daily needs. Now microwave technology is being developed to a higher frequency band (30 GHz-70 GHz) or even 100GHz. But, traditional microwave transmission media have a great loss in long-distance transmission. Traditional electronic microwave signal generators have many disadvantages such as a complex structure, large volume and high cost. In addition, there are many difficulties in generating a high-frequency signal. Under this background, microwave photonics [1-4] appear and become an interdisciplinary technology which combines microwave and photonics technologies.
Summary of Chapters
Chapter 1 Introduction: Provides background on microwave photonics and the need for high-frequency signal generation in modern communication systems.
Chapter 2 Optical generation of micro/millimeter wave technology: Explores various technologies for generating microwave signals optically, comparing heterodyne and external modulation methods.
Chapter 3 Optical external modulator: Details the theoretical principles and mathematical modeling of Mach-Zehnder modulators (MZM) and their modulation characteristics.
Chapter 4 Literature review: Surveys existing frequency multiplication schemes and analyzes typical generation structures reported in academic literature.
Chapter 5 Simulation for the MZM or DPMZM in VPI: Presents simulation results and phase analysis for various modulation states using VPI transmission Maker software.
Chapter 6 Microwave signal generation based on two parallel DP-MZMs: Discusses specific schemes for frequency 8-tupling and 12-tupling using parallel configurations of dual-parallel MZMs.
Chapter 7 New schemes for frequency 10-tupling microwave generation: Proposes and analyzes novel configurations for generating 10-tupling microwave signals.
Chapter 8 Experiment: Demonstrates the experimental verification of modulation indexes and frequency-quadrupling schemes in a laboratory setting.
Chapter 9 Conclusion and future work: Summarizes the thesis findings and suggests potential directions for future research in microwave photonics.
Chapter 10 References: Lists the academic sources and citations used throughout the research.
Keywords
Microwave Photonics, Mach-Zehnder Modulator, DPMZM, Frequency Multiplication, Optical Heterodyne, Millimeter Wave, Optical Fiber Communication, Signal Generation, Phase Noise, Modulation Index, Radio over Fiber, Sideband Suppression, Simulation, VPI, OptiSystem
Frequently Asked Questions
What is the core focus of this thesis?
The work focuses on generating high-frequency millimeter and microwave signals using optical techniques, overcoming the limitations of traditional electrical signal generation through microwave photonics.
Which modulation devices are primarily analyzed?
The study primarily utilizes and models Mach-Zehnder Modulators (MZM) and Dual-parallel Mach-Zehnder Modulators (DPMZM) as the key components for frequency multiplication.
What is the ultimate goal of the proposed schemes?
The goal is to achieve stable, high-frequency, and high-quality microwave signal generation while maintaining simple system structures and cost-efficiency.
What scientific methodology is utilized?
The methodology combines theoretical formula derivation with rigorous computer simulations (using OptiSystem and VPI software) and experimental laboratory validation.
How is frequency multiplication achieved?
Frequency multiplication is achieved by generating specific optical sidebands through external modulation and subsequently beating these sidebands in a photodetector to produce the desired frequency.
What characteristics define the study?
Key characteristics include high spectral purity, wide bandwidth, low phase noise, and the elimination of complex electrical components through all-optical approaches.
How does the use of DPMZM improve system performance?
The DPMZM architecture offers a higher extinction ratio, reduced insertion loss, and better stability, enabling more complex frequency multiplication factors (like 8-tupling or 12-tupling) compared to single MZM setups.
What specific result was achieved for 10-tupling generation?
The thesis proposed and validated two schemes for 10-times frequency multiplication, achieving high signal quality with a sideband suppression ratio (OSSR) greater than 25 dB.
How were experimental results reconciled with theory?
Experiments confirmed that the nested MZM modulation index follows the relationship m = π*V_RF / (2*V_pi), which was validated through comparison of simulated and measured optical power output.
What is the significance of the 8-times frequency multiplication scheme?
It demonstrates a filterless structure that simplifies system architecture, demonstrating significant improvement in frequency stability and reduction of complexity for real-world application.
- Quote paper
- Chongjia Huang (Author), 2017, Microwave photonic frequency multiplier with 10 times frequency multiplication, Munich, GRIN Verlag, https://www.grin.com/document/432864
