Highlights From the Conference Chairs

CLEO: Science & Innovations
Christophe Dorrer
University of Rochester, USA, cdorrer@lle.rochester.edu
Tara Fortier
National Institute of Standards and Tech., USA, tara.fortier@nist.gov

CLEO: Applications & Technology
Jin Kang 
Johns Hopkins University, USA, jkang@jhu.edu
Stephanie Tomasulo 
Naval Research Laboratory, USA, stephanie.tomasulo@nrl.navy.mil 

CLEO: Fundamental Science
Natalia Litchinitser 
Duke University, USA, natalia.litchinitser@duke.edu
Sergey Polyakov 
National Institute of Standards & Technology, USA, sergey.polyakov@nist.gov

Like in 2020, CLEO was run this year in an all-virtual format, which supported a large range of events complementing the high-quality technical program. The virtual format provided a convenient and accessible platform to support broad participation from members of the international optics community. While COVID19 has reduced everyone’s ability to do research and travel, the virtual conference was a great opportunity to present technical results, learn about new science and technology, network with peers, brainstorm on technical and non-technical topics of interest to the optics community, and develop one’s career. Live presentations and interactive participation from all attendees was encouraged during technical sessions, plenary sessions, and special events. 

Four luminaries in technical fields presented during the two plenary sessions. This was a great opportunity to learn about advanced topics that are of general interest to the optics community. Prof. Gisin (University of Geneva), highlighted the many aspects of quantum information science, from fundamental principles to commercial applications such as quantum key distribution and random number generators. Prof. Murnane (STROBE and JILA, University of Colorado at Boulder) presented recent advances in the development of high-harmonic quantum sources and applications that are made possible by the unprecedented control of these short-wavelength sources. Dr. O’Brien (PSIQuantum) discussed recent developments in quantum computing enabled by silicon photonics. Finally, Prof. Willner (University of Southern California) addressed the exciting progress in many aspects of optical telecommunications beyond optical fibers. The plenary session also hosted the awards ceremony recognizing the professional achievements from members of the three societies sponsoring CLEO (American Physical Society – Division of Laser Science Awards, IEEE Photonics Society, and The Optical Society).

Prof. Margaret Murnane presenting her plenary talk about “Harnessing Attosecond Quantum Technologies”

New this year, diversity and inclusion were highlighted during one of the plenary sessions: Prof. Johnson (University of Colorado at Boulder), the author of Inclusify: The Power of Uniqueness and Belonging to Build Innovative Teams, described practical means of how inclusion can help support diversity within the workplace. 

The CLEO workshops again addressed a large range of technical topics that are relevant to the optics community. Introduced in 2019, these events allow for interaction of the audience with a panel of specialists representing different viewpoints on a topic of interest. This year, the workshop topics included self-driving cars, photonic information processing, the contributions of optics to fight future pandemics, and the practical deployment of quantum technologies.

The status and recent progress in several technical topics were highlighted during the invited and contributed talks given at special symposia and Applications & Technology topical reviews. Three large events addressed high-power laser technology, advances in quantum technology, and photonics technologies for the COVID19 challenge. Focused sessions on other aspects of optics, photonics, optical telecommunications, and their applications were held throughout the week. 

A large variety of special events contributed to an exciting CLEO 2021. Panel-based events were held on community-wide topics such as publishing, career paths in optics, professional management, improving inclusion at conferences, and careers related to quantum technology. Companies demonstrated novel products and advanced applications during the Technology Showcase events. A memorial event highlighted the many technical contributions of Dr. Arthur Ashkin (2018 Physics Nobel Prize) with participation of former colleagues and other optics luminaries. OSA technical groups addressed progress and hot topics in ultrafast optical phenomena, additive manufacturing, integrated photonics, and metamaterials, while an update on the US strategy to promote research in ultrafast intense laser systems was given. 

Short courses given by specialists again provided the opportunity for students and professionals to learn about new technical topics or improve their knowledge. This is an excellent venue where students and scientists looking to break into a new field have the opportunity to learn directly from world-class experts!

Highlighted Plenary Speakers

Nicolas Gisin
Professor Emeritus, University of Geneva, nicolas.gisin@unige.ch
Professor, Schaffhasusen Institute of Technology, Geneva, Switzerland

Title: From Quantum Foundations to Quantum Communications and Back

Quantum information science started in 1991 with the insight that non-local quantum correlations are cryptographic keys [1]. This connected fascinating fundamental characteristics of quantum entanglement, the resource leading to non-local correlations, to potentially useful applications in modern cryptography. It was no longer possible to dismiss entanglement as an elusive property of some peculiar quantum states, as this property allows for highly timely applications in our information-based society. 

A couple of decades later, quantum key distribution was a commercial product, as well as quantum random number generators, e.g., in the form of low power consumption chips in smartphones. The next step will be the development of quantum networks. These are motivating entirely new fundamental questions, feeding thus back from application to foundations. A natural question is how to test the quantumness of a network, i.e., how to make sure that the network can’t be mimicked by a classical network. The answer brings back non-locality, but now in a new form, named network non-locality which builds on the fact that in a network there are several independent sources that feed many parties [2].

First satellite picture illustrating a quantum experiment [3]

[1] A. Ekert, Phys. Rev. Lett. 67, 661 (1991).
[2] for a review see A. Tavakoli et al., arXiv:2004.10700.
[3] N. Gisin et al., Rev. Mod. Phys. 74, 145 (2002).

Alan Eli Willner
Professor, University of Southern California, USA, willner@usc.edu

Title: Optical Communications: Innovations and Applications “Abound”

Optical communications has enjoyed tremendous impact over the past 50 years. Relatively soon after the concrete proposal of optical fiber communications was reported and the low-loss fiber invented, fiber-based communications dramatically impacted the way society transfers information. However, there are other key areas beyond fiber-based communications that were also envisioned ~50 years ago but are only recently emerging. Such emergence is due to enhanced capacity needs and critical innovations, including advances in photonic integrated circuits (PICs). This plenary talk dealt with 3 examples of the innovations and emerging applications of optical communications.

Overview of Alan Willner’s Plenary talk
  1. Free-space optical communications: As opposed to RF, optical links have high directionality and large bandwidth. There is great excitement in the recent emergence of deployed free-space optical links, be they through air or outer-space. Moreover, due to the extremely high losses of RF, even underwater links in the blue-green are gaining significant interest.
  2. Non-conventional wavelengths: Fiber systems are overwhelmingly in the near-IR, whereas free-space links can take advantage of a much wider frequency range, from THz to visible. Such systems may utilize: (a) native high-speed communications components at other frequencies, and/or (b) wavelength-band conversion of near-IR channels to other regions.
  3. Optical signal processing (OSP): OSP has long held the promise of high-speed operation and the avoidance of inefficient optical-electrical-optical conversion. Although OSP deployment has been limited, advances in PICs, power efficiency and multi-wavelength operation may soon enable the emergence of OSP for high-performance functions.
Alan Willner presenting his Poster at CLEO 1987 in Baltimore

Arthur Ashkin Memorial Symposium

Arthur Ashkin is known as the inventor of the optical tweezers. Arthur became captivated very early on by the effects that the momentum of light can exert on objects. This fascination started as a teenager while observing the effect of sunlight shining on a Crookes radiometer. This passion ultimately led, decades later, to the discovery that light pressure from two laser beams can immobilize objects if they are sufficiently transparent at the laser wavelength. Arthur quickly realized and demonstrated that by turning a laser beam upwards, small transparent spheres can be made to levitate, i.e., radiation pressure can compensate for gravity. About a decade later, Arthur demonstrated that a single laser beam, tightly focused by a microscope objective, can strongly capture objects in all three dimensions of space. A few years later, he discovered that optical trapping does not only work on inanimate objects but also on “living things.” Unlike what he feared, the optical power required to trap did not instantly kill the microorganisms. By using a laser at a wavelength where microorganisms were most transparent, they could be trapped for hours with little or no damage. But if the power was increased sufficiently, they would explode due to the presence of light. Arthur called this phenomenon, opticution, or death by light. 

Steven Chu speaks at the Arthur Ashkin Memorial Symposium

Before he started using lasers, Arthur had worked mostly with microwaves. When Arthur’s undergraduate studies in Physics were interrupted by World War II, he was hired to build high-power magnetrons for radar applications. Magnetrons have now become very common as they are part of microwave ovens. When Arthur started at Bell Labs after his Ph.D., he joined the microwaves research department. During his first decade at Bell Labs, Arthur worked on microwave amplifiers, in particular on the traveling-wave tube. He mentioned that his experience with microwaves was a great source of ideas that he applied later to optical frequencies. 

After retiring from Bell Labs, Arthur wrote review articles and a book on optical trapping. He started to work on solar power, especially on ways to develop technologies for harnessing the power of the sun at the lowest possible cost. Arthur would also regularly come to the picnics organized at the Crawford Hill Laboratory in Holmdel, New Jersey, where he would give very informative and entertaining speeches.  

More detailed summaries of Arthur Ashkin’s life can be found here: 

  • René-Jean Essiambre, “Arthur Ashkin: Father of the optical tweezers,” Proc. Natl. Acad. Sci., Vol. 118, No 7, paper e2026827118 (2021) 
  • René-Jean Essiambre, “In memory of Arthur Ashkin,” Nature Photon., Vol. 15, pp. 167-168 (2021)  
  • Photonics Society Newsletter, October 2020, Volume 34, Number 5, pp 16-17

Highlights From Selected Technical Sessions

More than 2,000 technical sessions were presented at CLEO, including talks from more than 200 invited speakers, covering 29 topic categories — from breakthrough ideas to real-world applications. Contributed talks are rigorously peer reviewed by the CLEO Committees. Some selected sessions:

Applications & Technology Topical Reviews

Emphasizes significant recent advances in the application of photonics technologies to address current real world problems. Presentations by leaders in their fields highlight how important advances are being realized.

Special Symposia

Comprised of invited and contributed papers, on areas deemed to be topical and of special interest to conference attendees.


Provides convivial, interactive, open fora to address topics not covered by traditional presentations, but that are of interest and importance to the CLEO community. Workshops offer an informal format to enable open discussion between moderators and panels of specialists and the audience to address technical or strategic questions that may lack clear consensus.

Short Courses

Covers a broad range of topic areas at a variety of educational levels, and taught by highly-regarded industry experts on a number of subjects. Whether you choose a course designed for beginners or for more advanced instruction, the small size of each class gives you an excellent opportunity for personalized instruction. Registrants receive one copy of the Course Notes, which were distributed onsite.

Special Events

Make the most of your attendance at CLEO with a range of networking and educational events. Special events range from receptions to career development programs.

Integrated Photonics for Artificial Intelligence

Integrated Photonics is enabling artificial intelligence (AI). The combination of photonics and AI for photonics-enabled applications is an exciting new prospect. Artificial neural networks (ANNs) constitute the core information processing technology in the fields of artificial intelligence and machine learning, which have witnessed remarkable progress in recent years, and they are expected to be increasingly employed in real-world applications. ANNs are computational models that mimic biological neural networks. They are represented by a network of neuron-like processing units interconnected via synapse-like weighted links. In particular, integrated photonic devices using reservoirs based on physical phenomena have recently attracted increasing interest in many research areas. Various physical systems, substrates, and devices have been proposed for realizing ANNs. A motivation for physical implementation of reservoirs is to realize fast information processing integrated photonic devices with low learning cost. In contrast, physical implementation of reservoirs can be achieved using a variety of physical phenomena in the real world, because a mechanism for adaptive changes for training is not necessary. Actually, integrated photonics is one of the candidates of unconventional computing paradigms based on novel hardware. Although design principles for conventional ANNs have been examined comprehensively, the following issues require further investigation: how to design physical reservoirs for achieving high computational performance and how much computational power can be attained by individual physical RC systems. Integrated photonics applied to AI has become a more important topic today and the session attracted a significant number of attendees. The audience not only came from the photonics community itself, but also from other AI related communities. Session goals were two-fold: one was to let our photonics community to be aware of this emerging direction, the other was to provide a platform for both integrated photonics and AI communities to discuss some future directions which will need experts in both areas to work together. 

Dr. Arash Kazemian from Yangzhou QunFa Company presenting an invited talk on “Machine Learning Based Optical Phased Arrays Design for on-Chip Solid State Lidar System”

Integrated Photonics in Neural Networks

At the session “Integrated Photonics in Neural Networks I,” Nicolas Fontaine from Nokia Bell Labs talked about multiplane light conversion to build unitary optical networks. Arash Kazemian from Yangzhou QunFa Company presented an invited talk on “Machine Learning Based Optical Phased Arrays Design for on-Chip Solid State Lidar System.” They are developing 3D OPAs for integrated solid state Lidar systems with potentially low cost, compact size, light weight, low power, high performance, and high reliability. It can be applied to autonomous driving vehicles, UAVs, smart imaging and robotics. Furthermore, it will not compromise the aerodynamics or the design aesthetics of the intelligent system.

Volker Sorger from George Washington University talked about “Photonic TPU & Memory for Machine Intelligence.” Here, he introduced a Photonic TPU (P-TPU), a PIC-based ASIC for vector matrix multiplication acceleration and reported on a programmable multi-level non-volatile photonic random access memory (P-RAM). 

David Moss from Swinburne University of Technology gave an interesting contributed talk on “Optical Neuromorphic Processing Based on Kerr Microcombs.” They reported a new approach to ONNs based on integrated Kerr micro-combs that is programmable, highly scalable and capable of reaching ultra-high speeds. They demonstrated a single perceptron at 11.9 Giga-OPS at 8 bits /OP, or 95.2 Gbps. They then demonstrated a convolutional accelerator at 11 Tera OPs/s.

Takuma Tsurugaya, NTT Device Technology Labs, NTT Corporation, talked about “Reservoir Computing with Low-Power-Consumption All-Optical Nonlinear Activation Using Membrane SOA on Si.” They demonstrated reservoir computing using a fiber delay line and membrane semiconductor optical amplifier on Si. Thanks to its small active volume and low fiber-coupling loss, the reservoir consumes only 43 mW for nonlinear activation.

At the session “Integrated Photonics in Neural Networks II,” David Brady from Duke University gave an invited talk on “Optical Processing for Artificial Neural Vision.” Convolutional neural networks have become established as the primary mechanisms for image processing over the past decade, while general purpose optical neural networks remain a long term project. In the near term optical pre-filters act as the first layers of electronic deep convolutional networks and enable 10-100x reduction in system power per reconstructed voxel.

Yidong Huang and Xue Feng, both from Tsinghua University, gave a presentation about “All-Optical Neural Network with Programmable Linear Transformation.” In their work, programmable arbitrary linear optical operations have been demonstrated on discrete phase-coherent spatial modes. Thus, they proposed and demonstrated a programmable ONN scheme for various image identification tasks.

In the following four contributed presentations, Santosh Kumar from Stevens Institute of Technology, talked about “Single-Pixel Image Classification via Nonlinear Optics and Deep Neural Network.” They proposed and experimentally demonstrated a hybrid system which utilizes a nonlinear mode-selective optical method to extract the features with single-pixel detection and subsequently recognize the high-resolution images from a deep neural network. Lorenzo De Marinis, Scuola Superiore Sant’Anna and Alessandro Catania, from University of Pisa talked about “A Codesigned Photonic Electronic MAC Neuron with ADC-Embedded Nonlinearity.” They presented a reduced-precision integrated photonic electronic multiply-accumulate (MAC) neuron with ADC-embedded nonlinearity. The proposed device trades off speed with resolution, outperforming both analog and digital electronic solutions in terms of speed and energy consumption. Mario Miscuglio, George Washington University, talked on “Massively-Parallel Amplitude-Only Fourier Optical Convolutional Neural Network.” Here they introduced a novel amplitude-only Fourier-optical processor paradigm and demonstrated a prototype system capable of processing large-scale ~(2,000×1,000) matrices in a single time-step and 100 microsecond-short latency, for accelerating machine-learning applications. Christopher Yeung, from University of California, Los Angeles, talked about “Conditional Machine Learning-Based Inverse Design Across Multiple Classes of Photonic Metasurfaces.” They presented a machine learning-based photonics design strategy centered on encoding image colors with material and structural data. Given input target spectra, their model can accurately determine the optimal metasurface class, materials, and structure.

Lidar and Artificial Intelligence

As lidar is one of the most important sensors in the future artificial intelligence, there was one Applications & Technology session devoted to this emerging field. Anton Lukashchuk, EPFL, talked about “Megapixel per Second Hardware Efficient LiDAR Based on Microcombs.” They showed a novel architecture for massively parallel FMCW lidar based on multi-heterodyne mixing of two triangular chirped soliton micro combs using a single laser source and a single coherent receiver. They demonstrated a proof of concept experiment with 5.6 MPix/s detection rates.

Li-Yang Chen, University of California, Los Angeles, talked on “A Pulsed-Coherent Lidar System With a Chip Based Optical Frequency Comb.” They demonstrated a pulsed-coherent lidar system with a microresonator generated optical frequency comb which achieves sub-10µm precision and 30-µm INLMax with a 5-MSa/s sampling rate.

Frank Rodriguez, University of California at Riverside, talked about “Hybrid Machine Vision Systems Achieve High-Speed Video Rates With Object and Scene Tracking.” Hybrid vision systems may enable real-time image processing in remote, power/energy-limited applications. They demonstrated 40k/17k frame-per-second self-motion inference rates with optical processing, which is 3 orders of magnitude faster than current all-electronic state-of-the-art.

Xianyi Cao, Shanghai Jiao Tong University, presented on “FMCW Ranging and Speed Measurement Based on Frequency Sweep Pre distortion of DFB Laser.” An iterative method for generating a linear frequency sweep from a DFB laser at 1550nm was demonstrated. An object with speed of ~6m/s at 7m was detected by the FMCW lidar, indicating a good sweep linearity.

Zhi Li, Tsinghua University, talked on “Solid-State FMCW LiDAR Based on a 2D Disperser.” By employing a tunable laser and a 2D disperser, they experimentally realized a frequency-modulated continuous-wave lidar system that performs ranging and two-dimensional non-mechanical beam-steering simultaneously. Reconfigurable high imaging resolution and precise ranging are achieved.

Andrew Schober from Fibertek, Inc. gave an invited talk on “Mission-Driven Design of Laser Systems for Space-Based Sensing and Communications.” He discussed how unique mission requirements drive laser design features including performance, size, weight, power consumption, and reliability in the context of specific lidar sensing and laser communications missions and systems.

Lucas Paulien, ONERA, presented on “Smoke Sensing with a Short-Range Elastic Micro-Lidar.” The aim of this work was to present the advances in aerosols profiling with a short-range elastic lidar system. Their results demonstrated the feasibility of short-range elastic micro-lidar measurements of smoke. The objective was to retrieve the radiative properties (backscattering) of soot particles.

CLEO Conference Virtual Exhibition

Even though we couldn’t meet face-to-face this year, the attendees could still meet and interact with exhibitors, make connections, and discover new technological developments on their own schedule. Here are just some of the ways for interaction:

Discover – Browse the exhibitor profiles at your own pace. Just hover over the logos on the website (https://www.cleoconference.org/home/virtual-exhibit/), and click on the exhibitor you like to visit.   

Connect & Engage – Stop by an exhibitor booth, drop your business card, or join private chats and group chats to learn more about the latest products and industry developments. There were close to a hundred companies participating at this year CLEO’s virtual exhibition.

CLEO 2021 may be over, but attendees can still access hundreds of hours of recorded technical sessions, special events and exhibition programming and the Virtual Exhibition. Access continues on the platform through 13 July 2021. Content access is based on registration type.

We hope to see you next year for CLEO 2022!