Crossing oceans: Loi Nguyen's engineering odyssey
Loi Nguyen arrived in the US with nothing but determination and went on to co-found Inphi, a semiconductor company acquired by Marvell for $10 billion. Now, the renowned high-speed semiconductor entrepreneur is ready for his next chapter.
“What is the timeline?”
It’s a question the CEO of Marvell, Matt Murphy, would pose to Loi Nguyen each year during their one-on-one meetings. “I’ve always thought of myself as a young guy; retirement seemed far away,” says Nguyen. “Then, in October, it seemed like the time is now.”
Nguyen will not, however, disappear. He will work on specific projects and take part in events, but this will no longer be a full-time role.
Early life and journey to the US
One of nine children, Nguyen grew up in Ho Chi Minh City, Vietnam. Mathematically inclined from an early age, he faced limited options when considering higher education.
“In the 1970s, you could only apply to one university, and you either passed or failed,” he says. “That decided your career.”
Study choices were also limited, either engineering or physics. Nguyen chose physics, believing entrance would be easier.
After just one year at university, he joined the thousands of ‘boat people’ that left Vietnam by sea following the end of the Vietnam War in 1975.
But that one year at university was pivotal. “It proved I could get into a very tough competitive environment,” he says. “I could compete with the best.”
Nguyen arrived in the US with limited English and no money. He found work in his first year before signing up at a community college. Here, he excelled and graduated with first-class honours.
Finding a mentor & purpose
Nguyen’s next achievement was to gain a full scholarship to study at Cornell University. At Cornell, Nguyen planned to earn his degree, find a job, and support his family in Vietnam. Then a Cornell academic changed everything.
The late Professor Lester Eastman was a pioneer researcher in high-speed semiconductor devices and circuits using materials such as gallium arsenide and indium phosphide. “Field-effect transistors (FETs), bipolar – any kind of high-speed devices,” says Nguyen. “I was just so inspired by how he talked about his research.”
In his senior year, Nguyen talked to his classmates about their plans. Most students sought industry jobs, but the best students were advancing to graduate school.
“What is graduate school?” Nguyen asked and was told about gaining a doctorate. “How one does that?” he asked and was told about the US Graduate Record Examination (GRE). “I hadn’t a clue,” he says.
The GRE deadline to apply to top US universities was only a week away, including an exam. Nguyen passed. He could now pursue a doctorate at leading US universities, but he chose to stay at Cornell under Professor Eastman: “I wanted to do high-speed semiconductors.”
His PhD addressed gallium arsenide FETs, which became the basis for today’s satellite communications.
Early career breakthroughs
After graduating, he worked for a satellite company focussing on low-noise amplifiers. NASA used some of the work for a remote sensing satellite to study cosmic microwave background radiation. “We were making what was considered the most sensitive low-noise receivers ever,” says Nguyen.
However, the work concluded in the early 1990s, a period of defence and research budget cuts. “I got bored and wondered what to do next,” he says.
Nguyen’s expertise was in specialised compound semiconductor devices, whereas CMOS was the dominant process technology for chip designs. He decided to undertake an MBA, which led to his co-founding the high-speed communications chip company Inphi.
While studying for his MBA, he met Tim Semones, another Inphi co-founder. The third co-founder was Gopal Raghavan whom Nguyen describes as a classic genius: “The guy could do anything.”
Building Inphi: innovation through persistence
The late 1990s internet boom created the perfect environment for a semiconductor start-up. Nguyen, Semones, and Raghavan raised $12 million to found Inphi, shorthand for indium phosphide.
The company’s first decade was focused on analogue and mixed-signal design. The market used 10-gigabit optics, so Inphi focused on 40 gigabits. But then the whole optical market collapsed, and the company had to repurpose.
Inphi went from designing indium phosphide chips at 40 gigabits-per-second (Gbps) to CMOS process circuits for memory working at 400 megabits-per-second (Mbps).
In 2007, AT&T started to deploy 40Gbps, indicating that the optical market was returning. Nguyen asked the chairman for a small team which subsequently developed components such as trans-impedance amplifiers and drivers. Inphi was too late for 40Gbps, so it focussed on chips for 100Gbps coherent optics.
Inphi also identified the emerging cloud data centre opportunity for optics. Initially, Nguyen considered whether 100Gbps coherent optics could be adopted within the data centre. However, coherent was too fast and costly compared to traditional non-return-to-zero (NRZ) signalling-based optics.
It led to Inphi developing a 4-level pulse-amplitude modulation (PAM4) chip. Nguyen says that, at the time, he didn’t know of PAM4 but understood that Inphi needed to develop technology that supported higher-order modulation schemes.
“We had no customer, so we had to spend our own money to develop the first PAM4 chip,” says Nguyen.
Nguyen also led another Inphi group in developing an in-house silicon photonics design capability.
These two core technologies – silicon photonics and PAM4 – would prove key in Inphi’s fortunes and gain the company a key design win with hyperscaler Microsoft with the COLORZ optical module.
Microsoft met Inphi staff at a show and described wanting a 100Gbps optical module that could operate over 80km to link data centre sites yet would consume under 3.5W. No design had done that before.
Inphi had PAM4 and silicon photonics by then and worked with Microsoft for a year to make it happen. “That’s how innovation happens; give engineers a good problem, and they figure out how to solve it,” says Nguyen.
Marvell transformation
The COVID-19 pandemic created unlikely opportunities. Marvell’s CEO, Matt Murphy, and then-Inphi CEO, Ford Tamer, served on the Semiconductor Industry Association (SIA) board together. It led to them discussing a potential acquisition during hikes in the summer of 2020 when offices were closed. By 2021, Marvell acquired Inphi for $10 billion.
“Matt asked me to stay on to help with the transition,” says Nguyen. “I knew that for the transition to be successful, I could play a key role as an Inphi co-founder.”
Nguyen was promoted to manage most of the Inphi optical portfolio and Marvell’s copper physical layer portfolio.
“Matt runs a much bigger company, and he has very well thought-out measurement processes that he runs throughout the year,” he says. “It is one of those things that I needed to learn: how to do things differently.”
The change as part of Marvell was welcome. “It invigorated me and asked me to take stock of who I am and what skills I bring to the table,” says Nguyen.
AI and connectivity
After helping ensure a successful merger integration, Nguyen returned to his engineering roots, focusing on optical connectivity for AI. By studying how companies like Nvidia, Google, and Amazon architect their networks, he gained insights into future infrastructure needs.
“You can figure out roughly how many layers of switching they will need for this and the ratio between optical interconnect and the GPU, TPU or xPU,” he says. “Those are things that are super useful.”
Nguyen says there are two “buckets” to consider: scale-up and scale-out networks. Scale-out is needed when connecting 10,000s, 100,000 and, in the future, 1 million xPUs via network interface cards. Scale-out networks use protocols such as Infiniband or Ethernet that minimise and handle packet loss.
Scale-up refers to the interconnect between xPUs in a very high bandwidth, low latency network. This more local network allows the xPUs to share each other’s memory. Here, copper is used: it is cheap and reliable. “Everyone loves copper,” says Nguyen. But copper’s limitation is reach, which keeps shrinking as signalling speeds increase.
“At 200 gigabits, if you go outside the rack, optics is needed,” he says. “So next-gen scale-up represents a massive opportunity for optics,” he says.
Nguyen notes that scale-up and scale-out grow in tandem. It was eight xPUs in a scale-up for up to a 25,000 xPU scale-out network cluster. Now, it is 72 xPUs scale-up for a 100,000 xPU cluster. This trend will continue.
Beyond Technology
Nguyen’s passion for wildlife photography is due to his wife. Some 30 years ago, he and his wife supported the reintroduction of wolves to the Yellowstone national Park in the US.
After Inphi’s initial public offering (IPO) in 2010, Nguyen could donate money to defend wildlife, and he and his wife were invited to a VIP retreat there.
“I just fell in love with the place and started taking up photography,” he says. Though initially frustrated by elusive wolves, his characteristic determination took over. “The thing about me is that if I’m into something, I want to be the best at it. I don’t dabble in things,” he says, laughing. “I’m very obsessive about what I want to spend my time on.
He has travelled widely to pursue his passion, taking what have proved to be award-winning photos.
Full Circle: becoming a role model
Perhaps most meaningful in Nguyen’s next chapter is his commitment to Vietnam, where he’s been embraced as a high-tech role model and a national hero.
He plans to encourage young people to pursue engineering careers and develop Vietnam’s high-speed semiconductor industry, completing a circle that began with his departure decades ago.
He also wants to spend time with his wife and family, including going on an African safari.
He won’t miss back-to-back Zoom calls and evenings away from home. In the last two years, he estimates that he has been away from home between 60 and 70 per cent of the time.
It seems retirement isn’t an ending but a new beginning.
ECOC 2023 industry reflections - Part 3
Gazettabyte is asking industry figures for their thoughts after attending the recent ECOC show in Glasgow. In particular, what developments and trends they noted, what they learned and what, if anything, surprised them. Here are responses from Coherent, Ciena, Marvell, Pilot Photonics, and Broadcom.
Julie Eng, CTO of Coherent
It had been several years since I’d been to ECOC. Because of my background in the industry, with the majority of my career in data communications, I was pleasantly surprised to see that ECOC had transitioned from primarily telecommunications, and largely academic, into more industry participation, a much bigger exhibition, and a focus on datacom and telecom. There were many exciting talks and demos, but I don’t think there were too many surprises.
In datacom, the focus, not surprisingly, was on architectures and implementations to support artificial intelligence (AI). The dramatic growth of AI, the massive computing time, and the network interconnect required to train models are driving innovation in fibre optic transceivers and components.
There was significant discussion about using Ethernet for AI compared to protocols such as InfiniBand and NVLink. For us as a transceiver vendor, the distinction doesn’t have a significant impact as there is little if any, difference in the transceivers we make for Ethernet compared to the transceivers we make for InfiniBand/NVLink. However, the impact on the switch chip market and the broader industry are significant, and it will be interesting to see how this evolves.
Linear pluggable optics (LPO) was a hot topic, as it was at OFC 2023, and multiple companies, including Coherent, demonstrated 100 gigabit-per-lane LPO. The implementation has pros and cons, and we may find ourselves in a split ecosystem, with some customers preferring LPO and others preferring traditional pluggable optics with DSP inside the module. The discussion is now moving to the feasibility of 200 gigabit-per-lane LPO.
Discussion and demonstrations of co-packaged optics also continued, with switch vendors starting to show Ethernet switches with co-packaged optics. Interestingly, the success of LPO may push out the implementation of co-packaged optics, as LPO realizes some of the advantages of co-packaged optics with a much less dramatic architectural change.
One telecom trend was the transition to 800-gigabit digital coherent optical modules, as customers and suppliers plan for and demonstrate the capability to make this next step. There was also significant interest in and discussion about 100G ZR. We demonstrated a new version with 0dBm high optical output power at ECOC 2023 while other companies showed components to support it. This is interesting for cable providers and potentially for data centre interconnect and mobile fronthaul and backhaul.
I was very proud that our 200 gigabit-per-lane InP-based DFB-MZ laser won the 2023 ECOC Exhibition Industry Award for Most Innovative Product in the category of Innovative Photonics Component.
ECOC was a vibrant conference and exhibition, and I was pleased to attend and participate again.
Loudon Blair, senior director, corporate strategy, Ciena
ECOC 2023 in Glasgow gave me an excellent perspective on the future of optical technology. In the exhibition, integrated photonic solutions, high-speed coherent pluggable optical modules, and an array of testing and interoperability solutions were on display.
I was especially impressed by how high-bandwidth optics is being considered beyond traditional networking. Evolving use cases include optical cabling, the radio access network (RAN), broadband access, data centre fabrics, and quantum solutions. The role of optical connectivity is expanding.
In the conference, questions and conversations revolved around how we solve challenges created by the expanding use cases. How do we accommodate continued exponential traffic growth on our fibre infrastructure? Coherent optics supports 1.6Tbps today. How many more generations of coherent can we build before we move on to a different paradigm? How do we maximize density and continue to minimize cost and power? How do we solve the power consumption problem? How do we address the evolving needs of data centre fabrics in support of AI and machine learning? What is the role of optical switching in future architectures? How can we enhance the optical layer to secure our information traversing the network?
As I revisited my home city and stood on the banks of the river Clyde – at a location once the shipbuilding centre of the world – I remembered visiting my grandfather’s workshop where he built ships’ compasses and clocks out of brass.
It struck me how much the area had changed from my childhood and how modern satellite communications had disrupted the nautical instrumentation industry. In the same place where my grandfather serviced ships’ compasses, the optical industry leaders were now gathering to discuss how advances in optical technology will transform how we communicate.
It is a good time to be in the optical business, and based on the pace of progress witnessed at ECOC, I look forward to visiting San Diego next March for OFC 2024.
Dr Loi Nguyen, executive vice president and general manager of the cloud optics business group, Marvell
What was the biggest story at ECOC? That the story never changes! After 40 years, we’re still collectively trying to meet the insatiable demand for bandwidth while minimizing power, space, heat, and cost. The difference is that the stakes get higher each year.
The public debut of 800G ZR/ZR+ pluggable optics and a merchant coherent DSP marked a key milestone at ECOC 2023. For the first time, small-form-factor coherent optics delivers performance at a fraction of the cost, power, and space compared to traditional transponders. Now, cloud and service providers can deploy a single coherent optics in their metro, regional, and backbone networks without needing a separate transport box. 800 ZR/ZR+ can save billions of dollars for large-scale deployment over the programme’s life.
Another big topic at the show was 800G linear drive pluggable optics (LPO). The multi-vendor live demo at the OIF booth highlighted some of the progress being made. Many hurdles, however, remain. Open standards still need to be developed, which may prove difficult due to the challenges of standardizing analogue interfaces among multiple vendors. Many questions remain about whether LPO can be scaled beyond limited vendor selection and bookend use cases.
Frank Smyth, CTO and founder of Pilot Photonics
ECOC 2023’s location in Glasgow brought me back to the place of my first photonics conference, LEOS 2002, which I attended as a postgrad from Dublin City University. It was great to have the show close to home again, and the proximity to Dublin allowed us to bring most of the Pilot team.
Two things caught my eye. One was 100G ZR. We noted several companies working on their 100G ZR implementations beyond Coherent and Adtran (formerly Adva) who announced the product as a joint development over a year ago.
100G ZR has attracted much interest for scaling and aggregation in the edge network. Its 5W power dissipation is disruptive, and we believe it could find use in other network segments, potentially driving significant volume. Our interest in 100G ZR is in supplying the light source, and we had a working demo of our low linewidth tunable laser and mechanical samples of our nano-iTLA at the booth.
Another topic was carrier and spatial division multiplexing. Brian Smith from Lumentum gave a Market Focus talk on carrier and spatial division multiplexing (CSDM), which Lumentum believes will define the sixth generation of optical networking.
Highlighting the approaching technological limitation on baud rate scaling, the ‘carrier’ part of CSDM refers to interfaces built from multiple closely-spaced wavelengths. We know that several system vendors have products with interfaces based on two wavelengths, but it was interesting to see this from a component/ module vendor.
We argue that comb lasers come into their own when you go beyond two to four or eight wavelengths and offer significant benefits over independent lasers. So CSDM aligns well with Pilot’s vision and roadmap, and our integrated comb laser assembly (iCLA) will add value to this sixth-generation optical networking.
Speaking of comb lasers, I attended an enjoyable workshop on comb lasers on the Sunday before the meetings got too hectic. The title was ‘Frequency Combs for Optical Communications – Hype or Hope’. It was a lively session featuring a technology push team and a market pull team presenting views from academia and industry.
Eric Bernier offered an important observation from HiSilicon. He pointed to a technology gap between what the market needs and what most comb lasers provide regarding power per wavelength, number of wavelengths, and data rate per lane. Pilot Photonics agrees and spotted the same gap several years ago. Our iCLA bridges it, providing a straightforward upgrade path to scaling to multi-wavelength transceivers but with the added benefits that comb lasers bring over independent lasers.
The workshop closed with an audience participation survey in which attendees were asked: Will frequency combs play a major role in short-reach communications? And will they play a major role in long-reach communications?
Unsurprisingly, given an audience interested in comb lasers, the majority’s response to both questions was yes. However, what surprised me was that the short-reach application had a much larger majority on the yes side: 78% to 22%. For long-reach applications the majority was slim: 54% to 46%.
Having looked at this problem for many years, I believe the technology gap mentioned is easier to bridge and delivers greater benefits for long-reach applications than for short-reach, at least in the near term.
Natarajan Ramachandran, director of product marketing, physical layer products division, Broadcom
Retimed pluggables have repeatedly shown resiliency due to their standards-based approach, offering reliable solutions, manufacturing scale, and balancing metrics around latency, cost and power.
At ECOC this year, multiple module vendors demonstrated 800G DR4 and 1.6T DR8 solutions with 200 gigabit-per-lane optics. As the IEEE works towards ratifying the specs around 200 gigabit per lane, one thing was clear at ECOC: the ecosystem – comprising DSP vendors, driver and transimpedence amplifier (TIA) vendors, and VCSEL/EML/silicon photonics vendors – is ready and can deliver.
Several vendors had module demonstrations using 200 gigabit-per-lane DSPs. What also was apparent at ECOC was that the application space and use cases, be it within traditional data centre networks, AI and machine learning clusters and telcom, continue to grow. Multiple technologies will find the space to co-exist.