PSF – Portable Ultra Stable Frequency Sources and Applications

The objective of this topic is to bring together researchers from the distinct disciplines of environmental sensing, frequency metrology, and telecommunications to the mutual benefit of all three. Optical fibers make excellent sensors, as the slightest fiber strain can measurably alter the polarization, frequency, and phase of the guided optical field. The global reach of terrestrial and submarine telecommunications fiber presents an extraordinary opportunity to develop a distributed sensing network, for purposes such as earthquake detection, disaster recovery, lightning strike detection and to improve the robustness of the global telecommunication network. Measurement sensitivity is greatly improved using sources with the high frequency and phase stability developed by the metrology community for optical atomic clocks and low noise optical oscillators. By bringing together experts in these fields, this topic’s goals are threefold. First, it aims to promote understanding of the requirements of ultrastable frequency sources, including portability and remote operation, and to discuss the current state-of-the-art in performance. Second, develop connections between those who develop state-of-the-art photonic sources, those who have access to terrestrial and transoceanic fibers, and those with expertise in environmental sensing applications. Third, promote other applications that can benefit from portable ultrastable optical clocks and oscillators in fiber and atmospheric sensing, as well as optical communications, quantum systems, and space-based applications. 

What is an ultrastable reference, and why are they not portable?

At the heart of every ultra-stable, Hz-linewidth laser is a high quality-factor optical resonator cavity, typically comprised of high reflectivity mirrors bonded to a glass spacer. Locking a laser’s frequency to this reference cavity transfers the length stability of the cavity to the laser frequency, resulting in laser linewidths below 1 Hz and fractional frequency instabilities below Δf/f = 10-16. This performance has crowned optical oscillators as the most frequency-stable sources across the electromagnetic spectrum. However, a state-of-the-art optical resonator used in conjunction with an optical clock typically occupies a volume exceeding 1 cubic meter, is held in high vacuum with multiple layers of thermal isolation, and free-space lenses and mirrors are used to efficiently couple light into the optical cavity. The large size and weight of these systems, as well as their delicate optical alignment, has largely relegated their use to staid laboratory environments.

Recognizing the utility of such stable, narrow linewidth sources for applications outside of a controlled laboratory, the frequency metrology community has begun to develop compact, robust, and portable sources. This includes chip-scale frequency combs and optical resonator cavities, temperature- and acceleration-insensitive cavity designs, ultra-stable optical fiber-based resonators, compact vapor cell atomic clocks, and low-noise time and frequency dissemination techniques. However, these compact sources are often developed without detailed knowledge of the range of potential applications, nor their requirements in terms of performance and robustness. As these sources are at the cusp of being “deployment ready”, we feel it is the perfect time to connect these frequency metrology researchers with scientists who will benefit from their use.

Fiber sensing networks and where are they headed? 

Optical fibers are excellent environmental sensors, leading to dedicated fiber deployment for tasks such as structural and environmental monitoring. With the increasing deployments of telecom fibers, the natural question arises about the potential to use the global telecom grid for sensing purposes. Today, telecom fibers are deployed in all areas, including areas not covered by traditional fiber sensors such as the deep ocean floor. Expanding the ability to use this infrastructure for sensing purposes therefore has a large potential to improve areas such as environmental monitoring, including weather monitoring and earthquake detection, network reliability and outage prevention. 

We sense our environment using digital signal processing outputs from mass produced telecom transceivers and dedicated sensing techniques such as optical time domain reflectometry (OTDR). As the distances of the networks grow from meters to >10 000km, the requirements of stability of the lasers and timing between nodes are well beyond what is available for telecom. For example, detecting small changes in length of a 10000km submarine fiber via a transponder or a OTDR is limited by slow laser frequency fluctuations, preventing reliable phase sensing over long fibers such as submarine fibers. Frequency stabilized metrology-grade lasers can overcome these challenges and hit the ultimate sensitivity. 

Why everybody needs a portable frequency reference?

In addition to the fiber sensing applications, there are many other areas of research that can benefit from portable ultrastable optical references.  This includes space communications, atmospheric sensing, optical communications, wireless communications, time transfer, geodetic sensing, quantum information systems, and synchronization of large-scale experiments.   By incorporating talks from researchers within these fields, this meeting will promote networking and idea-sharing in the use of ultrastable sources across multiple disciplines.


We envision this Topical Meeting to encompass the three main sub-topics of Sources, Current Applications, and Future Application Development. These sub-topics in turn will include:

  • Stable CW and pulsed laser sources
  • Global fiber sensing networks using deployed fiber, submarine and terrestrial
  • Frequency agile lasers (swept source)
  • Limits of coherent optical communications
  • Coherent LIDAR/OFDR/OTDR
  • Field Trials (Fiber, Land, Space)
  • Performance and portability trade-space
  • Optical clocks in space
  • Hollow Core Fiber applications
  • Frequency stability from mid-IR to visible wavelengths
  • Multimodal sensing & digital signal processing

ROP – Reconfigurable Optics and Photonics

Traditional optical systems typically operate with fixed functionalities post-fabrication. In contrast, emerging reconfigurable optics and photonics technologies enable dynamic function tuning and thereby realize significantly enhanced performance. These fields have been investigated intensively recently and opened up exciting opportunities for agile manipulation of light propagation, processing and interaction with matter, in free-space and/or on-chip.

In particular, optical metasurfaces and metamaterials integrated with active components allow the local and global tuning of optical responses. Harnessing a variety of tuning mechanisms, a wide range of dynamically-controlled meta-optical devices and systems have been realized for free-space phase/amplitude/polarization modulation, such as spatial light modulators, tunable filters, beam steering components, varifocal lenses, switchable holograms, display, adaptive thermal camouflage, tunable absorbers and emitters, etc. On the other hand, reconfigurable photonic integrated circuits have also been explored extensively on various photonics platforms, demonstrating advanced on-chip programable architectures for optical switching, routing, modulation, signal processing, etc. Such technological advancements have equipped traditional photonic integrated circuits with unprecedented versatile capabilities in critical applications such as optical communications, computing, sensing, imaging, positioning, microwave photonics, 5G, quantum photonics, etc.

This topic covers key aspects in frontier research, technologies and perspectives of reconfigurable optics and photonics. We aim to bring together experts from academia, government research institutions and industry to discuss recent advances, assess key challenges and outline future directions in these exciting fields.

SDM – Space Division Multiplexing

Space division multiplexing (SDM) in multi-mode and multi-core fibers has been a major topic in optical communications since the beginning of the past decade. SDM research aims at exploiting spatial diversity in optical transceivers, fibers, amplifiers, routers etc. to increase the per-link transmission capacity while reducing cost, complexity, and eventually energy consumption. Research on SDM has been fueled worldwide by numerous multi-national research projects in the USA, Europe, Japan and China, and is further making its way towards field deployment, e.g. in a recently launched submarine cable installment, where SDM amplification solutions have been employed, while standardization of certain SDM fibers is now actively discussed with a strong industry interest.

The SDM topical meeting intends to gather the key players in SDM research from around the world to establish an overview of current research regarding devices, fibers and systems. Secondly, we aim to stimulate an open discussion on the challenges and opportunities envisaged in the development of massive parallel transmission systems that are necessary in response to the ever-increasing demand for data capacity. Finally, we plan to explore applications of SDM technologies and devices in optics-related research areas that are not necessarily connected to fiber-optic communications. 

Space Division Multiplexing (SDM) is technically co-organized by the technical committee on Extremely Advanced Optical Transmission Technologies (EXAT), IEICE, Japan, promoting 3-M (multi-core, multi-mode, multi-level modulation) technologies.

SIMP – Silicon-Integrated Mid-Infrared Photonics

Background and actuality: The mid-infrared wavelength domain has a myriad of applications in surveillance, free-space communications, anti-counterfeiting, produce inspection, identifying and sorting, biomedical research, environmental pollution monitoring, and biochemical sensing and imaging, to name a few. For example, biochemical sensors operating in the mid-infrared spectral range (2-8 μm) are becoming rapidly valuable because the fundamental vibrational transitions of molecules are more than two orders of magnitude stronger in the mid-infrared spectral region than in the visible and near-infrared, thus allowing the detection of distinctive spectral fingerprints of molecules. The ever-increasing market size of mid-infrared applications, which is expected to reach USD 1.76 Billion by 2026 at a CAGR of 11.4% from 2018 to 2026, also proves the potential of the technology.

While the technology for mid-infrared optoelectronic devices has steadily advanced for the past few decades at the component levels, the integration of such devices for the realization of end-user applications with cost-effective and small-form-factor solutions still remains challenging. The biggest challenges arise from the integration of III-V and II-VI compound semiconductor materials (e.g., InSb, PbSe). In fact, besides being costly, these semiconductors are rather incompatible with the Si-based CMOS process. Therefore, the development of Si-compatible mid-infrared optoelectronic devices holds the key to the seamless integration of various mid-infrared components and necessary electronic circuitry into a CMOS architecture.

In the last few years, all over the world an extensive amount of research efforts has been put on the development of Si-compatible mid-infrared optoelectronic devices. Although III-V and II-VI compound semiconductor materials generally achieve superior performance (especially for laser applications), the realization of monolithically integrated photonic-electronic circuits using Si-compatible processes has been driving this research field very intensively. Years of efforts and investments have recently resulted in numerous breakthrough discoveries for material syntheses and fabrication techniques. The research activity on (Si)GeSn is a good example for the synthesis of new mid-infrared materials; (Si)GeSn is inherently compatible with Si and possesses direct bandgap leading to sufficiently high light-emitting efficiency for lasing applications as well as good optical absorption property for detection and imaging applications. Hybrid approaches to integrate III-V/II-VI on Si-compatible platforms using heteroepitaxy and/or wafer bonding have also been attracting a great deal of attention, with the aim to combine the superior optoelectronic properties of compound semiconductors with Si-enabled scalability and CMOS compatibility. Also, emerging materials such as two-dimensional van der Waals materials have also been explored for Si-integrated mid-infrared photodetectors.

Given that there currently exist several active communities pursuing the emerging research areas in the field of mid-infrared optoelectronics, bringing researchers together for the 2021 IEEE Summer Topical Meeting will present a timely opportunity to exchange ideas and discuss the current scientific and technological bottlenecks facing the development of Si-compatible mid-infrared optoelectronics. The meeting will not only serve as a platform for researchers to exchange the newest development of the field but also foster the generation of new ideas and interdisciplinary collaborations and therefore enable the quick growth of the emerging areas to become mature. In addition, bringing researchers who are using different approaches to achieve a common technological objective will allow them to directly discuss the advantages and limitations in each paradigm. This will certainly be an enriching experience to all participants. This interaction of key people in mid-infrared optoelectronics should help the community to move the technology forward and overcome potential barriers in the realization of integrated mid-infrared optoelectronic systems.

While there might seem to be several conferences covering similar topics, they all lack the focus that this workshop will emphasize. For example, IEEE Group-IV Photonics is intended to cover Group-IV integrated photonics but mainly on the performance of devices and components based on Si, Ge, and SiGe, new device structures, or new concepts of mid-infrared optoelectronic integration. IEEE Photonics Annual meeting covers broad integrated photonic topics in very scattered sessions and does not provide a centralized theme for the emerging integrated mid-infrared optoelectronic materials. The ECS meeting has focused sessions biannually on Ge, SiGe, GeSn and GeC but its scope is mainly for material growth and its application for electronic devices. SPIE and MRS all have the mechanism to allow new topics to be added into their broad range of symposiums, but the turn-around time is normally more than one year and the associated conferences are often too big with many parallel sessions which is not a desired platform for researchers to have extensive information exchanging in the frontiers of integrated mid-infrared optoelectronics. Therefore, the organizers all believe that this Summer Topical Meeting is the best route to pursue.

Target audience: This topical meeting targets both academia and industry participants interested in mid-infrared integrated photonics. The proposed topic actually builds on the success of previous Topical Meeting Symposia: “Silicon-Integrated Mid-Infrared Photonics” in 2020 and 2021, “Mid-infrared Optoelectronics in Silicon and Emerging Materials” in 2019, “Integrated Photonics for the Mid-Infrared” in 2018 and 2017. The latter grew up from the 2015 and 2016 sessions that covered first the mid-infrared fibers together with semiconductor optoelectronic devices, and later focused on new pathways of integration. Due to recent but sustained interest to the Si-based mid-infrared integration and related material/device developments, the team decided to propose this year again the focused topic “Integrated Mid-Infrared Photonics”. The intended topic will target the new developments in the mid-infrared integrated photonics appeared in the last two-three years. Any traditional integrated photonics will only be included if in synergy with the emerging technologies. This year again, we expect to have approximately 25-30 invited presentations and a few student talks. In total, 30-35 presentations are expected over two days.

SQL – Semiconductor Quantum Light Sources and Their Applications

This conference intends to provide an excellent opportunity to learn about advances in physics and applications of semiconductor quantum light sources through invited talks by renowned scholars and through contributed presentations by active researchers. The conference attempts to create a stimulating environment for extensive discussions and potential collaborations with researchers worldwide. The conference will bring together the scientific communities highly concerned with the physics and integration of semiconductor quantum devices (lasers and LEDs), in particular for applications in the areas of quantum communications, quantum sensing, quantum computing, quantum integration, quantum chemistry, and quantum biology.

The topics include, but are not limited to:

  • Quantum devices (quantum cascade & interband cascade lasers, quantum dot & dash lasers)
  • Vertical-cavity surface-emitting devices
  • Photonic-crystal semiconductor lasers
  • Nanoscale semiconductor lasers
  • Novel material systems, structures, and technologies
  • Short pulse lasers and mode-locked lasers
  • Semiconductor laser comb generation
  • Quantum photonic integrated circuits
  • Quantum communication
  • Squeezed states of light in semiconductor lasers
  • Single-photon detectors
  • Single photon sources
  • Entangled-photon-pair emitters
  • Quantum photonics
  • Lasers on silicon

TI – Terahertz Imaging: Progress, Challenges, and Applications

Terahertz science and technology have greatly progressed over the past two decades to a point where the THz region of the electromagnetic spectrum is now a mature research area with many fundamental and practical applications. Furthermore, THz imaging is positioned to play a key role in many industrial applications, as THz technology is steadily shifting from university-grade instrumentation to commercial systems. In this context, this summer topical aims at reviewing the latest research results in the fields of terahertz (THz) high-resolution imaging and fast image acquisition instrumentation, as well as their various applications in industrial process monitoring, material characterization, agro-processing industry, biophotonics, and other fields. The meeting would welcome scientific contributions dealing with the state-of-the-art in the fields of materials, components, instruments, and methods of THz technology that open up new avenues for developing portable and ergonomic sensors, spectroscopic and imaging systems that are capable of solving complex pressing problems in material science and chemistry, security and non-destructive remote sensing, as well as biology and medicine.

Within this topic the conference will cover the following subjects:

  • advanced THz materials and related fabrication technologies;
  • devices for THz applications, including photoconductive emitters antennas and quantum cascade lasers, nonlinear devices, terahertz spintronics;
  • theoretical and experimental methods, as well as instrumentation for THz imaging, Time-Domain, and Fourier-domain spectroscopy, hyperspectral imaging, holography, tomography, and microscopy;
  • digital signal processing and inverse ill-posed problems in THz spectroscopy and imaging;
  • micro and nano terahertz imaging: theory methodologies and applications;
  • flexible fibers and hard waveguides for the THz-wave delivery to hardly accessible objects, imaging, and medical diagnostics;
  • modeling the THz-wave – complex media, scattering regimes, and tissue interactions, including the effective medium and radiation transfer theories;
  • effects of tissues and cells exposure to THz waves; THz dosimetry;
  • medical diagnosis and therapy using THz waves;
  • multimodal methods of spectroscopy and imaging for fundamental research, astrophysics, and astrochemistry, industrial and biomedical applications.
  • cross-disciplinary applications in THz imaging

UWB – Ultra-wideband Optical Fibre Communication Systems

Topic description:

Ultra-wideband optical fibre communication systems (UWB OFCS) have emerged in recent years as a burgeoning field of interest, addressing near-to-mid-term requirements in optical networking. Systems based on UWB technology are attractive because they leverage the existing, massive investment in single mode optical fibre plant worldwide, by making use of the whole low-loss transmission window (~1250-1650nm), a potentially cost-effective and green solution to increasing network capacity.  This topic area seeks to bring together researchers from around the world with interests in UWB OFCS, and related subjects, to explore recent progress in UWB component technologies, sub-systems, architectures, and systems.  We aim to stimulate an open discussion on the latest advances, opportunities, and challenges faced by scientists and engineers working in these areas, and to foster a forum for the generation of new ideas, directions, and collaborations. 

The topic area seeks contributions related to ultra-wideband fibre optical fibre communication systems (UWB OFCS) and include:

  • Optical fibre communication modelling and performance prediction
  • Optical fibre component and sub-system technologies, and physical integration
  • Optical fibre communication system demonstrations
  • System design and operation
  • Spectral power optimisation, bandwidth allocation and network management
  • Optical power management techniques and capacity optimisation
  • Application of novel techniques such as machine learning to UWB OFCS
  • Cost and energy performance analyses for network applications