This optical researcher is on the hunt for the most efficient transmission of information

In the never-ending race to meet the insatiable global demand for communication, optical transmission researchers have an overriding objective: speed.

Our global communications infrastructure is powered by high-capacity fiber optic cables and Nokia Bell Labs has been at the forefront of seeking to constantly improve these data rates.

There are two main ways to do that. The first is by increasing how quickly a laser can “blink,” thereby sending light pulses down a strand of fiber at a higher rate. The second is how much information you can reliably cram into each one of these pulses through advanced encoding techniques.

The latter is the domain of Hussam Batshon. He says his job is to “make the internet faster,” and he does that by encoding more information to increase the efficiency of each transmission.

Batshon said he focuses on improving this spectral efficiency in two ways. The first involves fine-tuning how the light signal is modulated - adjusting properties like its intensity and phase - to better represent information. The second is by adding redundancy to the information, something called forward error correction. This adds extra, controlled data to help the receiver detect and correct errors.

“I'm trying to put in more information. But I'm also trying to work on the redundancy part so that this additional information makes more sense to the receiver,” he said. “These go hand-in-hand to make spectral efficiency higher.”

It’s an area of expertise called multi-dimensional coded modulation that has been widely adopted to optimize spectral efficiency in high-order quadrature amplitude modulation (QAM) formats.

Batshon will be presenting a novel approach to such a coded modulation scheme in a talk next week in San Francisco, California at the Optical Fiber Communications Conference, the most prestigious gathering of the optical research community. It is celebrating its 50th anniversary and some 13,500 participants from 83 countries are expected to attend.

There’s more than the Shannon Limit 

The fastest way we know how to communicate is through an elaborate network of high-capacity fiber optic cables. These cables contain strands of fiber, each about the diameter of a human hair, that make up the backbone of the Internet and allow us to transmit millions of text, audio and video communications at the speed of light.

These fibers already connect data centers, factories, campuses and homes. The modems, mobile phone antennas and Wi-Fi systems we use today are all ultimately connected by optical fibers as well. 

In an era of ultra-high-definition video streaming, 5G (and soon 6G) mobile communications, cloud computing and gaming and the first truly practical artificial intelligence systems, there is an exponential increase in the global demand for communication channels. Therefore, we will only depend more on such fiber optics in the future.

But there is also a fundamental limitation to the amount of information that can be sent over any communications channel.  It’s called the Shannon Limit, the immutable law of physics that Nokia Bell Labs’ most famous mathematician Claude Shannon established in Information Theory 75 years ago.

Some of Batshon’s fellow researchers focus on transmitting data as close as possible to the Shannon Limit and they continue to push for new and improved world records. But as gains become more marginal, Batshon thinks the future lies in optimizing efficiency.

“Our goal is to get as close as possible to the Shannon Limit. We're not going to break it, nor do we need to,” he said. “We continue to refine our techniques and develop more sophisticated approaches, but the improvements are becoming increasingly incremental as we approach saturation near the Shannon Limit.”

But by working on efficiency, rather than outright speed, he feels there are still more gains to be made in his expertise of probabilistic shaping and coded modulation.

“You can either transmit slightly more information or extend its reach over a greater distance. But probabilistic shaping has inherent constraints, as it relies on a predetermined probability distribution, which can restrict its flexibility,” he explained. “My paper (at OFC) proposes an additional layer that enhances forward error correction by enabling the interaction between the redundancy and the probabilistic shaping at the receiver. This approach improves error correction, ultimately enabling more efficient information transmission.”

A life of changes

Batshon was born and raised in Jordan, where he always had a passion for math, science, computers and solving jigsaw puzzles.

He earned his B.Sc. in Electrical Engineering from the University of Jordan and then, thanks to a Fulbright Scholarship, continued his education in the United States, completing his M.S. and Ph.D. in Electrical Engineering at the University of Arizona.

His doctoral dissertation, Coded Modulation for High-Speed Optical Transport Networks, laid the groundwork for his future research in advanced modulation formats and coding techniques.

During his studies, he gained hands-on industry experience through internships at NEC Laboratories America and Tyco Telecommunications.

Upon graduation, he joined SubCom (formerly Tyco Telecommunications) as a Senior Member of Technical Staff. His early work focused on long-distance underwater cables that transmitted information from one continent to another.

Then he moved to NEC Laboratories America, Inc. as a Senior Researcher in the Optical Networking and Sensing group. There, he broadened his research scope to include neural network-based optical transmission impairment modeling and compensation for submarine systems.

In August 2022, he finally landed at Nokia Bell Labs. It was a career culmination in more ways than one.

“It has significantly shifted the trajectory of my work. I once focused primarily on theory, but now I’m deeply engaged in the experimental domain,” he explained.

“Working for Bell Labs has always been a dream of mine. It’s such a well-known establishment with so many Nobel Prizes, so for me it’s very prestigious to work here. I feel like I am part of history.”

He said he’s also drawn to the culture and has become involved in a variety of inclusion and diversity efforts.

“This is the first time I truly feel at home,” he said. “I just love it. I see myself here for the long run.”

Batshon’s love for structure and problem-solving extends to his personal life. He still enjoys solving jigsaw puzzles. The biggest one he completed had 39,000 pieces. He also enjoys writing and making artisanal soap. And he doesn’t stray too far from science in his other hobbies either, conducting hands-on science experiments with the children of close friends.

“Anything that makes you meditate and focus on measurements,” he explained. “I love baking, because it also requires measurements.”