In this thesis, a novel scheme to optically generate a microwave signal employing frequency quadrupling and octupling schemes based on external modulation are proposed. Similarly, the sextupling technique is also analysed and simulated. Frequency quadrupling and the octupling scheme are based on carrier suppression and undesired harmonic distortion suppression utilizing an integrated dual-parallel Mach Zehnder Modulator (DPMZM); thus avoiding the use of electric phase shifter and optical phase shifter. Secondly, filterless features and fast frequency tuning of this technique is particularly attractive for optical upconversion in wave division multiplexing radio over fibre system. For verification, 30 GHz millimetre wave with more than 16.2 dB RFSSR and 60 GHz with more than 16.3 dB millimetre wave have been generated from a 7.5 GHz frequency wave by simulation and its operating principle and mathematical analysis has been performed. Performance of scheme has been characterised under different condition including DC drift of MZM, different amplitudes of RF inputs and different extinction ratios of MZM.
In addition to this, various external modulation techniques based on previous research papers are theoretically and mathematically analysed and simulated to compare with the performance and reliability of the newly generated system. In addition to this, the figure of merits of frequency multiplication is also investigated based on the phase noise, tunability of frequency and system stability analysis, and maximum gain.
At the present context, the demand for telecommunications, electronic warfare technologies and the high-speed internet is highly increasing. Such things have a great influence on modern society. Therefore, to fulfil these demand, wideband signal processing is needed which can be achieved using microwave photonics due to its unique features like low loss, compactness, immunity to the electromagnetic interference (EMI), strong capacity and high system reliability.
Table of Contents
Chapter-1: Introduction
1.1 Background
1.2 Limitations and structural problem of previous microwave frequency generation
1.3 New solutions to microwave frequency generation:
1.4 Aim of Project:
1.5 Scope of study
1.6 Synopsis.
1.8 Summary.
Chapter-2: Microwave Photonic and its Link components
2.1 Introduction:
2.2 History of microwave photonics:
2.3 Optical generation of Microwave Signals:
2.3 Component of Microwave photonic generation:
2.3.1 Optical source:
2.3.2 Optical Modulator:
2.3.3 Dual Parallel Mach Zehnder Modulator:
2.3.4 Fibre optic cables:
2.3.5 Optical filter
2.3.6 Photodetector:
2.3.7 Erbium-doped fibre amplifiers (EDFA):
2.4 Passive components:
2.4.1 Fibre optical Coupler:
2.4.2 Optical Splitter.
Chapter-3: Techniques of Microwave photonic frequency Multiplication:
3.1 Introduction:
3.2 Techniques of microwave photonic frequency multiplier:
3.2.1 Optical injection Locking:
3.2.2 Optical Phase Lock Loop (OPLL):
3.2.3 Optical Injection Phase locking:
3.3.4 External Modulation Technique:
3.3 Summary:
Chapter-4: Figure of merit of Frequency multiplier:
4.1 Introduction:
4.2 Phase noise Performance:
4.3 Frequency Tunability:
4.4 System stability
4.4 Power loss:
4.5 Summary:
Chapter-5: Literature Review
5.1 Introduction:
5.2 A microwave photonic frequency doubling technique:
5.3 A microwave photonic frequency quadrupling techniques:
5.3.1 A photonic microwave frequency quadrupling using series cascaded of two MZM
5.3.2 A photonic microwave frequency quadrupling using DPMZM without optical filter.
5.3.3 A photonic microwave frequency quadrupling using DPMZM without optical filter without using RF phase shifter.
5.4 A photonic microwave frequency sextupling using cascaded module:
5.4.1 A photonic microwave frequency sextupling using series cascaded MZM and optical filter
5.4.2 A photonic microwave frequency sextupling using DPMZM and intensity modulator in cascade without optical filter
5.4.3 A photonic microwave frequency sextupling using DPMZM without optical filter
5.5 A microwave Photonic Octupling technique
5.5.1 A photonic microwave frequency octupling using two series cascading DPMZM without optical filter.
5.5.2 A photonic microwave frequency octupling using two parallel cascading DPMZM without optical filter.
5.6 Analysis and Discussion:
5.7 Summary
Chapter-6: A novel photonic microwave frequency quadrupling using single DPMZM
6.1 Introduction:
6.2 Schematic Diagram:
6.3 Operating Principle:
6.4 Mathematical Analysis:
6.5 Simulation:
6.6 Simulation result and discussion:
6.7 Advantage:
6.8 Disadvantage:
6.9 Summary:
Chapter-7: A novel photonic microwave frequency octupling using two cascades DPMZM
7.1 Introduction:
7.2 Schematic Diagram:
7.3 Operating Principle:
7.4 Mathematical Analysis:
7.5 Simulation:
7.6 Simulation result and discussion:
7.7 Advantages:
7.8 Disadvantages:
7.9 Summary:
Chapter 8: Conclusion and Future Work:
8.1 Conclusion:
8.2 Future Work:
Research Objectives and Topics
The primary objective of this thesis is to design and analyze efficient microwave photonic frequency multipliers that generate higher frequency signals (6 or 8 times) from lower frequency inputs, specifically addressing the limitations of electronic frequency multipliers and previous optical schemes by utilizing integrated Dual Parallel Mach-Zehnder Modulators (DPMZM) and external modulation techniques to achieve broad bandwidth, low transmission loss, and high spectral purity.
- Design of novel sextupling and octupling frequency multiplier architectures.
- Implementation of carrier suppression techniques to eliminate the need for complex optical filtering.
- Performance characterization via OPTISYSTEM simulation software.
- Investigation of key performance metrics including frequency tunability, phase noise, and system stability.
- Comparative analysis of the proposed schemes against existing external modulation techniques.
Excerpt from the Book
3.2 Techniques of microwave photonic frequency multiplier:
Microwave photonic frequency multiplier using a technique called optical heterodyning in which two optical waves having different wavelengths beat in the photo detector to generate a microwave signal. An electrical RF signal is generated at the photo detector output with a frequency equivalent to the wavelength spacing between two optical waves.
Let us consider, two optical wave having Amplitude ‘E01’ and ‘E02’ and angular frequency of ‘ω1’ and ‘ω2’ and having a phase of Φ1 and Φ2
Then, optical waves is given by
E1(t) = E01 cos[(ω1t + Φ1)]
E2(t) = E02 cos[(ω2t + Φ2)]
Since, there is a limited bandwidth of the photo detector, the current at the output of photo detection is
IRF = A cos[(ω1 - ω2)t + (Φ1 - Φ2)]
From equation [3.2.3], it shows that the new frequency of mm wave is equal to the wavelength spacing between two optical waves(ω1 - ω2) and also with the phase difference (Φ1 - Φ2) between the two optical sources. Since, laser has a wide wavelength range so it is used as a carrier signal of THz frequency. Here in our thesis, we have used a continuous wave laser of 1550 nm wavelength range and carrier frequency of 193.1 THz. So it provides a broad band -width but the phase term of equation [3.2.3] of two optical source are not correlated which gives high phase noise.
Summary of Chapters
Chapter-1: Introduction: This chapter introduces the project's goal to design a microwave photonic frequency multiplier and highlights the limitations of traditional electronic and previous optical generation techniques.
Chapter-2: Microwave Photonic and its Link components: This chapter details the fundamental components of photonic links, including lasers, modulators, and photodetectors, while covering the history and theoretical principles of microwave photonics.
Chapter-3: Techniques of Microwave photonic frequency Multiplication: This chapter reviews various techniques for optical frequency multiplication, such as optical injection locking and heterodyning, and justifies the focus on external modulation.
Chapter-4: Figure of merit of Frequency multiplier: This chapter establishes the performance criteria for frequency multipliers, specifically discussing phase noise, frequency tunability, and system stability.
Chapter-5: Literature Review: This chapter provides a comprehensive survey of academic work on frequency multipliers, categorizing existing techniques for doubling, quadrupling, sextupling, and octupling.
Chapter-6: A novel photonic microwave frequency quadrupling using single DPMZM: This chapter proposes a novel, filterless frequency quadrupling scheme using a single DPMZM and presents the corresponding numerical simulations and performance analysis.
Chapter-7: A novel photonic microwave frequency octupling using two cascades DPMZM: This chapter presents a new filterless octupling frequency generation scheme using two cascaded DPMZMs and verifies the design through simulation.
Chapter 8: Conclusion and Future Work: This chapter summarizes the thesis findings on integrated DPMZM-based frequency multiplication and outlines potential future research directions.
Keywords
Microwave photonics, Mach-Zehnder Modulator, DPMZM, Frequency multiplication, Optical communication, Fibre optics, Signal processing, Radio over fibre, Millimetre wave, Carrier suppression, Phase noise, Optical filter, Laser, System stability, Frequency tunability
Frequently Asked Questions
What is the core focus of this research project?
The work primarily focuses on designing advanced microwave photonic frequency multipliers capable of generating higher frequency signals (sextupling and octupling) using external modulation techniques to overcome current telecommunication limitations.
Which key technologies and components are central to this study?
The study centers on the use of Dual Parallel Mach-Zehnder Modulators (DPMZM), continuous wave (CW) lasers, Erbium-doped fibre amplifiers (EDFA), and photodetection systems to achieve high-frequency signal generation.
What is the main objective or research question?
The primary aim is to develop simple, cost-effective, and high-performance frequency multiplier architectures that minimize reliance on complex optical filters and electronic phase shifters while ensuring high spectral purity.
Which scientific methods are utilized for verification?
The proposed schemes are analyzed using mathematical derivations based on Bessel functions and verified through numerical simulations performed in the OPTISYSTEM environment.
What is covered in the main body of the thesis?
The main body covers theoretical analysis of optical signal modulation, detailed design of various multiplier architectures (doubling, quadrupling, sextupling, octupling), and a rigorous literature review of existing photonic techniques.
How would you characterize this thesis using specific keywords?
The research is best characterized by keywords such as Microwave photonics, DPMZM, Frequency multiplication, Carrier suppression, and Radio over fibre.
How does the proposed DPMZM scheme avoid the need for optical filters?
The proposed schemes utilize integrated DPMZM structures configured in specific biasing modes (like maximum or minimum transmission points) to intentionally suppress the optical carrier and unwanted sidebands, rendering additional filtering components unnecessary.
Why is the stability of the system emphasized in the simulations?
System stability is crucial for long-term reliability in high-speed telecommunications; the thesis explores how bias drift and non-ideal RF input signals impact the output quality to ensure robust performance.
- Arbeit zitieren
- Raj Krishna Karmacharya (Autor:in), 2017, Microwave Photonics Sextupling and Octupling Frequency Mutiplication, München, GRIN Verlag, https://www.grin.com/document/494303
