Microwave photonics is a fast-developing field that seeks to exploit the interaction between lightwaves and microwaves. This interaction offers opportunities for innovative devices, subsystems, systems and networks that can seamlessly interconnect microwave and optical domains. In this pursuit, microwave photonics often provides a new platform to realize new functionalities and also seeks to perform existing functionalities of microwave systems by exploiting recent developments in photonics domain to achieve improved performance. Applications of microwave photonics can be found in broadband wireless systems, radars, astronomy, space and electronic warfare. The tutorial will provide an exposure to the basics of lightwave-microwave interfaces, followed by an in-depth discussion of key unique performance metrics needed to describe and understand microwave photonics applications. It will then outline the latest developments in applications such as antenna remoting (in the context of 5G), filtering, photonic mixing and photonic beam forming for radars.

Professor Thas (Ampalavanapillai) Nirmalathas
Thas Nirmalathas is a Professor of Electrical and Electronic Engineering at The University of Melbourne, Australia. He is also the research group leader for the Electronic and Photonic Systems Group at the same university.
Prof Nirmalathas obtained his BEng and PhD in Electrical and Electronic Engineering from the University of Melbourne in 1993 and 1998 respectively. Between 2000 and 2004, he was the Director of Photonics Research Laboratory (Melbourne Node of Australian Photonics CRC) and also the Program Leader of Telecommunications Technologies Program. From 2004 to 2006, he was the Program Leader for the Network Technologies Research Program in NICTA. He was also the acting Lab Director of VRL in 2007. Between 2006 and 2008, He was the Research Group Manager of the Networked Systems Group of Victoria Research Laboratory (VRL) at the National ICT Australia (NICTA), a premier Australian research centre of excellence in ICT. Between 2010 and 2013, he was the Head of Department of Electrical and Electronic Engineering. Between 2013 and 2014, He was the associate Director for the Institute for Broadband-Enabled Society. In 2012, he co-founded the Melbourne Accelerator Program (Australia’s first university-based startup accelerator). He was its Director between 2012-2015 and provided the academic leadership between 2015 and 2017. Between 2014 and 2019, He is also the Director of Networked Society Institute – an interdisciplinary research institute focusing on challenges and opportunities arising from the society’s transition towards a networked society.
He has written more than 400 technical articles and currently hold 3 active international patents. His current research interests include energy efficient telecommunications, access networks, optical-wireless network integration and broadband systems and devices. He has held many editorial roles with the IEICE Transactions in Communications, IEEE/OSA Journal of Lightwave Technology and Photonics and Networks SPIE Journal. He is a Senior Member of IEEE, a member of Optical Society of America and a Fellow of the Institution of Engineers Australia.

Integrated microwave photonics (IMWP) starts being commonly used to refer to the development of microwave photonic techniques using photonic integration technology. The key advantage is that enables placing the crucial components of the microwave photonic function on a photonic integrated circuit (PICs), avoiding optical path length differences among components, improving the performance of the implemented functions.
These improvements are required as different fields of application for microwave photonic technology, like 5G wireless communication, radar and aerospace ecosystems and automotive are demanding increasing levels of performance to meet the challenges in terms of higher data rates (100 Mb/s per user with peaks up to 20 Gb/s), ultra-low latency (<1ms) and high reliability with lower costs and higher volumes. The approach is aided by the efforts across Europe and United States to establish photonic integration technology platforms with generic foundry approach.

Guillermo Carpintero is Full Professor at the Electronics Technology Department of Carlos III University of Madrid (UC3M), co-director of the Optoelectronics and Laser Technology Group (GOTL) and Director of the Graduate School of Engineering and Basic Sciences of UC3M. Received the Telecommunication Engineering degree from Polytechnic University of Madrid (UPM) in 1993 and the PhD from UC3M in 1999, awarded with the Extraordinary Doctoral Distinction. Has over 25 years of research experience, having coordinated European projects and over 10-year experience in academic positions at UC3M School of Engineering. I am IEEE Senior Member, member of the editorial board of IET Optoelectronics journal and member of the Board of Stakeholders of the Photonics21 European Technology Platform. I have published over 200 contributions in journals and international conferences, delivering above 15 invited talks.

Increasing mobile traffics induced by smart mobile devices, virtual reality service(VR), and augmented reality(AR) services require a continuous capacity expansion of wireless networks, and 5G network would provide 20 Gb/s data rate and 1 ms latency. There are multiple new technologies to deliver 5G capabilities such as new radio specifications, millimeter wave transmission, massive MIMO, beamforming, small cells, and so on. The carrier frequencies for 5G is divided into two frequency bands, below 6 GHz and above 6 GHz (mmWave), which is much higher than carrier frequency of 4G. Thus, the distance of wireless path become shorter and the penetration of optical fiber become deeper into end users.
A cost-effective fiber connection or optical access network to remove service shadowing area is very important issues for both outdoor and indoor network for 5G and beyond. To avoid loss of the connectivity for 5G and beyond, we could make a small scale cell around a distance of about 250-300 m. Recently, there have been extensive researches to implement cost-effective solution of fiber connection for mobile networks including high-speed/low-latency PON and analog radio-over fiber (RoF). The hybrid PON combined with WDM and TDM could be used to mobile data transmission for small cell backhaul since it provides low latency and easy capacity expansion. The RoF technology maintains the advantages of CPRI while reducing optical transmission speed significantly, which will well suited for indoor network. In this paper, we review optical access technologies for 5G and beyond, and introduce some recent feasibility demonstrations.

Hwan Seok Chung received the Ph.D. degree in electronics engineering from the Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea, in 2003. In 2003, he was a Postdoctoral Research Associate with KAIST, where he worked on hybrid CWDM/DWDM system for metro-area network. From 2004 to 2005, he was with KDDI R&D Laboratories, Inc., Saitama, Japan, and had involved in research on wavelength converter and regenerator. Since 2005, he has been with the Electronics and Telecommunication Research Institute, Daejeon. His current research interests include fronthaul and backhaul for 5G and beyond, high-speed PON, and indoor network. Dr. Chung served as a Technical Committee Member of the OFC, Optoelectronics and Communications Conference (OECC), CLEO-PR, MWP, CLEO-PR, and Photonic West. He received the Best Paper Awards from the OECC in 2000 and 2003, as well as from the ETRI in 2011 and 2012.

Microwave photonic techniques offer a promising solution to implement RF signal processing with unique advantages of wide frequency range, large bandwidth and immunity to electromagnetic interference. They have potential applications in radar systems, satellite communications, electronic warfare, and the radio astronomy. Detection and characterization of low-power RF signals over a broad frequency range in the complex electromagnetic environment are a real challenge due to high power interference signals. In this report we will present our recent work about the microwave signal processing with optoelectronic oscillator (OEO). The low-power RF signal detection by using a tunable OEO is analyzed and experimentally demonstrated. The frequency down-conversion without external local oscillators is realized by the developed OEO system. The optimization scheme for improving the OEO based detection system is also investigated.

Xiuyou Han received the Ph.D. degree in Optical Engineering from the Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences (CAS), China, in 2006. In July 2006, he joined the School of Physics and Optoelectronic Engineering, Dalian University of Technology (DUT), China, as a as an Assistant Professor, where he became an Associate Professor in 2009, and a Full Professor in 2016. From 2014 to 2015 he was a Visiting Scholar in the Microwave Photonics Research Laboratory, University of Ottawa, Canada. Since 2017, he has been a Full Professor in the School of Optoelectronic Engineering and Instrumentation Science (OEIS), DUT. Now, he is Associate Dean of OEIS, DUT.
His current research interests include microwave photonics and integrated photonics. He has authored or coauthored more than 100 research papers in peer-reviewed journals and conference proceedings. He has 17 patents authorized by National Intellectual Property Administration, PRC.

Optoelectronic oscillators (OEOs) have been widely studied in recent years as a microwave photonics system to generate microwave signals with ultra-low phase noise, thanks to the high-quality-factor of the optoelectronic feedback loop. However, there are still some limitations in a traditional OEO, including large mode building time, stringent requirements for the loop filter to achieve single mode operation, as well as large size and weight. Here we report three OEOs based on Fourier domain mode locking (FDML), parity-time (PT) symmetry and photonic integrated circuits to overcome the above three limitations, respectively. Frequency scanning microwave waveforms are generated directly from a FDML OEO cavity, which breaks the limitation of mode building time. Single mode oscillation is achieved in a PT symmetric OEO without the need of filters with narrow bandwidth, which opens a new avenue for mode selection in a microwave photonics system. All of the optical devices needed in the OEO loop are monolithically integrated on chip in the integrated OEO, which has a very compact size and weight.

Prof. Ming Li received the Ph.D. degree in electrical and electronics engineering from the University of Shizuoka, Hamamatsu, Japan, in 2009. In 2009, he was with the Microwave Photonics Research Laboratory, School of Electrical Engineering and Computer Science, University of Ottawa, Ottawa, ON, Canada, as a Postdoctoral Research Fellow. In 2011, he was with the Ultrafast Optical Processing Group, INRS-EMT, Montreal, QC, Canada, as a Postdoctoral Research Fellow. In 2013, he was with the Institute of Semiconductors, Chinese Academy of Sciences, as a Full Professor under the support of Thousand Youth Talents Program. He has authored more than 120 high-impact journal papers. His research interests include integrated microwave photonics and its applications, ultrafast optical signal processing, and high-speed real-time optical measurement and sensing.

In the past few decades, photonic techniques have been intensively studied to improve the capabilities of modern radar systems, such as large bandwidth, low loss transmission and electromagnetic immunity. In our previous works, a microwave photonic synthetic aperture radar (SAR) is developed and experimentally demonstrated. In the transmitter, microwave photonic frequency multiplication is used to generate a linearly-frequency-modulated (LFM) radar signal; while in the receiver, photonic stretch processing is employed to receive the reflection signal. The presented system operates in Ku band with an instantaneous bandwidth up to 5 GHz, and is vehicle-mounted for a series of SAR and inverse SAR imaging tests in the field trial. A SAR image of the ground surface is obtained through motion compensation and imaging algorithms, achieving a high two-dimensional resolution of 3 cm (range) × 4 cm (cross-range). Furthermore, a microwave photonic dual-band radar operating in C-band and Ku-band is proposed with photonic-assisted stretch receiving. In the receiver, the echoes and reference signals of C-band and Ku-band are applied to two parallel pairs of sub-modulators, which are biased at the peak points and null points respectively, resulting in two stretched signals with different frequencies. Thus operation in dual-band based on a unified system is achieved. An experimental demonstration in C-band and Ku-band with a bandwidth of 850 MHz and 3600 MHz is conducted. The above works show the potential of photonic technique to overcome the conventional radar bandwidth bottleneck and promote the performance of modern radar systems, which can be further applied in target recognition and earth observation.

Dr. Wangzhe Li is currently the head of the National Key Lab of Microwave Imaging Technology, Institute of Chinese Academy of Sciences (IECAS). He graduated from University of Ottawa as a PhD in 2013. Dr. Li did his postdoctoral research in Prof. Jianping Yao's group in University of Ottawa and in Prof. Larry Coldren’s group in UCSB until the end of 2015. Then Dr. Li joined IECAS with the support of the "100 Talent Project of Chinese Academy of Sciences" and was entitled to "1000 Plan Program for Young Talents" (2017). Dr. Li’s major research interests include microwave photonics, photonic integrated circuits, photonic-assisted radar and its applications. Dr. Li has published over 60 papers in peer-reviewed journals. In 2017, Dr. Li's group develop the first prototype of a microwave photonic radar and successfully obtained the ISAR and SAR imaging through a series of field trials.

Single Mode Fabry-Perot laser diode (SMFP-LD) has shown significant effects on digital photonics and optical signal processing due to the prominent advantages such as low power consumption, simple and easy configuration, and low cost. Recently, the use of SMFP-LDs on demonstrating RF signal generation has shown its potential in microwave photonics (MWP) domain too. In this paper, we discuss the use of SMFP-LDs in MWP for signal generation, hoping and the switching of RF signal. Injection locking with negative wavelength detuning is discussed, illustrating its benefits over positive injection locking for RF signal generation and output signal quality. Also, multi-injection locking in a single SMFP-LD is demonstrated to generate multiple RF signals which are of the same of different RADAR bands. Then after, the hoping between the generation of microwave, millimeter wave and, simultaneous microwave and millimeter wave using a single SMFP-LD is demonstrated. As a proof of concept for the switching of RF signal, 2 Gbps 16-bit NRZ signal is used as a control signal to switch the generation of RF signals using SMFP-LDs. The switching speed of less than 40 ps is observed. With the modification in the control unit, switching of multiple RF signal generation can be easily obtained using SMFP-LDs which can be used for other techniques of RF generation providing flexibility and reconfigurability of the proposed scheme. With the modification on the control signal as a random bit sequence generator, the proposed scheme can be used for the secure military communication besides other conventional application such as radars, 5G communications, sensing and detection, and others.

Bikash Nakarmi received Ph.D. degree in Information and Communication Engineering from Korea Advanced Institute of Science and Technology (KAIST) , Daejeon, Rep. of Korea in 2012. Prof. Nakarmi joined College of Electronic and Information Engineering, Nanjing University of Aeronautics and Astronautics (NUAA), China, in 2016, where he is currently a professor in t Key Laboratory of Radar Imaging and Microwave Photonics (Nanjing Univ. Aeronaut. Astronaut.), Ministry of Education.
His research is focused on the development of optical blocks used in optical communication and networks using Fabry-Pérot laser diode, bio-sensors based on nano-structures and microwave photonics. From 2012 to 2013, he worked as a Research and Development Manager in InLC technology, Korea and as a Post-doctoral Researcher at Nanjing University (2012-2014), China. From 2014 to 2016, he was a Research Professor at KAIST. Prof. Nakarmi has authored and co-authored over 60 research papers, including 30 peer-reviewed journals and 30 papers in conference proceedings and several invited talks and workshop. Prof. Nakarmi is a member of the Optical Society of America, IEEE Photonics Society, and SPIE. Prof. Nakarmi had served as a committee member in SPIE photonics ASIA 2012 and a reviewer of several peer-reviewed IEEE and OSA journals.

Microwave Photonics has the unique potential to enable ultra-high bandwidth microwave signal processing, to transport the microwave signal via waveguides over kilometres of lengths with almost no losses and to be immune against electromagnetic interference. Integrated electronics is a mature technology with libraries for almost everything in signal processing. Therefore, the connection between both might enable new, integrated devices for microwave, ultra-high bandwidth signal processing demands.
For the processing of ultra-high bandwidth, microwave signals we exploit the frequency time coherence and the dispersion engineering. The frequency and time domain are equivalent to each other, i.e. each signal in the time domain has a corresponding frequency domain representation. Both are connected via the well-known Fourier transform equations. This inherent connection might enable the processing and measurement of very short, ultra-broadband microwave signals, directly in the frequency domain with integrated photonic-electronic devices. By the engineering of the dispersion of an optical element, new degrees of freedom for the design of microwave photonic filters are enabled. In the talk, after an introduction into time-frequency coherence and dispersion engineering, special signal processing demands like microwave filtering, time-lenses, analogue-to-digital (ADC) and digital-to-analogue conversion DAC will be discussed. First preliminary, experimental results will be presented and the roadmap to integrate these devices into electronic-photonic silicon chips will be introduced.

Thomas Schneider received the diploma degree in electrical engineering from the Humboldt Universität zu Berlin, Germany, in 1995, and the Ph.D. degree in physics from the Brandenburgische Technische Universität Cottbus, Germany in 2000.
From 2000 to 2014 he was with the Hochschule für Telekommunikation (HfT) in Leipzig, Germany. From 2006 to 2014 he was the head of the Institut für Hochfrequenztechnik at the HfT. Since 2014 he has been the head of the THz-photonics group at the Technische Universität Braunschweig.
Dr. Schneider was a guest professor at the Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland, a guest scientist at the Deutsche Telekom Innovation Laboratories and the Fraunhofer Heinrich Hertz Institute Berlin.
His current research interests include integrated and microwave photonics the photon-phonon coupling in nano-waveguides and the exploitation of frequency-time coherence for signal processing.
Dr. Schneider is the author and co-author of 4 books, more than 160 publications and more than 30 patents or patent applications.

Six-port receiver is widely used in microwave society. In this talk, an introduction of optical six-port receiver in microwave photonics will be introduced. Microwave photonic applications based on optical six-port receiver, such as image-reject mixer, RF channelizer, photonics-based radar, will also be presented.

Zhengzhou Tang received the M.S. degree in Information Engineering from Nanjing University of Aeronautics and Astronautics, Nanjing, China, in 2015. He is currently a joint PhD student in the Key Laboratory of Radar Imaging and Microwave Photonics (Nanjing Univ. Aeronaut. Astronaut.), Ministry of Education, and =the Photonics Research Group, Ghent University. His research interests are microwave photonic mixing and silicon optomechanics. He received the 2017 Graduate Student Fellowship of IEEE Photonics Society.

With the rapid development of wireless communications, the demand for microwave technology is growing towards large bandwidth and high-frequency band. Due to the advantages of broad bandwidth, low loss and immunity to electromagnetic interference (EMI), microwave photonic coherent receiver has become more attractive and has been a promising technique for wideband wireless access networks, antenna remoting, radar and other applications. In this presentation, the microwave photonic coherent receivers with high bandwidth, high dynamic range or functional integration would be introduced. The proposed microwave photonic frequency downconverter supplies an ultra-wideband and high-purity alternative for the signal processing in microwave photonic applications. The proposed link with high dynamic range has great flexibility, simple structure and convenient operation, and it can be applied in both the single-octave and multi-octave communication systems. The functional integration of coherent receivers consists of LO doubling, quadrupling, phase shift or frequency conversion. Due to the LO frequency doubling and quadrupling, the frequency requirement of the LO signal can be greatly decreased for the high-frequency receiver and transmitter. The integrated phase-tunable mixer provides a compact alternative with low cost and high purity for the transceiver in the phase-coded radar systems and phased-array beam forming networks. The proposed microwave photonic coherent receivers can be applied in various communication systems such as radar and 5G wireless communications.

Yunxin Wang received Ph.D. degree from the Tianjin University in 2009. She is currently an associate professor in Beijing University of Technology. Her research interests include microwave photonic technology, optical information processing, and integrated device design. She was selected by Beijing Municipal Education Commission's Young Top Talents Training Program and Beijing University of Technology Youth Hundred Program.

In conventional microwave (MWP) systems, the bandwidth keeps unchanged during the electronic-to-optical (E-O) conversion and the optical-to-electronic (O-E) conversion. Here we propose and demonstrate a novel MWP system where the bandwidth is stretched during the E-O conversion and compressed during the O-E conversion. The proposed bandwidth scaled MWP system provides some new and valuable features. Firstly, the bandwidth of the input signal is greatly magnified after the E-O conversion so that the requirement of the frequency resolution of the optical devices is effectively reduced. One of the examples is a novel high resolution reconfigurable microwave wave-shaper. Using this bandwidth scaling technology, we manage to map a reconfigurable optical wave-shaper with lower frequency resolution of tens of GHz into a microwave one with resolution of tens of MHz. Secondly, the bandwidth is compressed but the phase keeps preserved during the O-E conversion. As a result, the phase response is remarkably magnified from the optics to the microwave. With this feature, we can greatly magnify the group delay variation by around 200 times from optics to microwave and a dispersion enlargement of about 40000 times is also obtained. We believe that this novel concept of “bandwidth scaling” can provide a potential routine in many MWP applications.

Feifei Yin received his B.Sc. and Ph.D. degrees in electronic science and technology from Tsinghua University, Beijing, China, in 2007 and 2012, respectively.
Since June 2012 he has been a Postdoctoral Research Fellow with the State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications (BUPT), Beijing, China. He is now an Associate Professor in BUPT.
Feifei Yin has published over 50 papers on journals and international conferences, including more than 20 papers published by IEEE (Institute of Electrical and Electronics Engineers) and OSA (optical society of America). His current research interests include microwave photonics, optical fiber communications, and integrated photonics.

The integration of non-Hermitian mechanism and microwave photonic technique is an emerging field of research that can be used to implement novel functionalities that are difficult to achieve with traditional techniques. In this talk, I will first present our recent work using a special non-Hermitian system, i.e., a parity-time (PT) symmetric system, in an opto-electronic oscillator (OEO) for the generation of single-tone microwave photonics with ultra-low phase noise. Our experimental results show that PT symmetry provides an easy solution to the long-lasting model selection challenge in a long-cavity OEO. Then, I will introduce how multiplexing techniques in optical communications can be used to further improve the overall performance of a PT-symmetric microwave photonic system. Lastly, I will discuss how the high-speed microwave photonic technique, including waveform generation, signal sampling and real-time spectrum analyzing, can be used to study the dynamics in a PT-symmetric system.

Prof. Jiejun Zhang joined the Institute of Photonic Technology at Jinan University, Guangzhou, China in 2018. From 2017 to 2018, he was a photonic engineer at Ciena Corporation, Canada. He received his PhD degree in Electrical Engineering and Computer Science from the University of Ottawa, Canada in 2017, after which he continued his post-doc research in the Microwave Photonics Research Laboratory. He received the M.Sc. degree in Optical Engineering from the Huazhong University of Science and Technology, Wuhan, China, in 2013, and the B.Eng. degree in Electronic Science and Technology from the Harbin Institute of Technology, Harbin, China, in 2010.