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Julie Sheridan Eng

Julie Sheridan Eng, CTO, Coherent

Julie Sheridan Eng, CTO, Coherent

Julie Sheridan Eng was named Coherent’s CTO in October 2022 after three years running the photonics manufacturer’s optoelectronic devices and modules business unit. In recent years, she has been involved primarily in the fibre optic communication and 3D sensing areas.

"Datacom is moving from 100G/lane to 200G/lane and from 400 Gbps to 800 Gbps to 1.6 Tbps modules. These advances are driving innovation in optical components such as GaAs vertical-cavity surface-emitting lasers (VCSELs), InP directly modulated lasers (DMLs), InP electro-absorption modulated lasers (EMLs), InP CW lasers, InP modulators, and silicon photonics modulators, as well as InP and SiGe detectors," she said. 

She believes one of the biggest challenges in datacom will be making the necessary advances in optical components on the timeline the industry needs them. 

"These are serious physics advances to get to 200 Gbps. I can remember when people were saying they didn’t think a VCSEL could operate above 10 Gbps, or a DML above 20 Gbps. There were also a lot of non-believers that EMLs could achieve uncooled performance, which has since been demonstrated. So, we are already achieving speeds and performance that people thought unachievable just a few years ago. But we need to keep innovating at a dramatic pace to keep up with the growth in bandwidth demand."

On the sensing side, Eng said customers are interested in multi-junction lasers for increased output power per die size area. This requires new long-wavelength VCSELs or edge-emitting lasers, as well as sensors. 

"The goal will be to have competitive products in the consumer, AR/VR, and automotive space. One significant challenge for sensing is that, unlike communications, there are no standards," she said.

Specialised requirements for optical components used in AR/VR, and in-cabin sensing and for LiDAR in the automotive sector, will also drive innovation, she predicts. There is also interest in SWIR (shortwave infrared) imaging around 1300 nm, said Eng.

"Finally, in order to decrease cost, complexity, and size in both communications and in sensing, diffractive optics and wafer-scale optics are being deployed. All of these devices and components require advances not only in device physics and design to meet performance and reliability, but also in fabrication capability to make them manufacturable at the needed volume and cost targets."

Julie began her career at AT&T Bell Laboratories, where she led the development of laser-based datacom transceivers, but would consider pursuing a career in biophotonics if starting out now: "It’s an interesting area and will have longevity for the future. I like the idea that there are medical and health implications, and the work that you do may directly help people."

A tireless advocate of women’s contributions to STEM, Julie is a past chair of the IEEE Committee on Women in Engineering and currently serves on the SPIE Executive Advisory Group.

"I have worked with and been helped by many people in this industry. I had the great fortune to work with both Jerry Rawls at Finisar and Chuck Mattera at AT&T, II-VI, and now Coherent. And, of course, I have had significant help from my husband, Lars Eng. We both have big jobs, and there is no way either of us could have achieved what we’ve achieved in our careers without the support of the other."

Julie was elected a fellow of Optica in 2022 for distinguished contributions to the advancement of optics and photonics, and was elected to the Optica board as a director-at-large. She has published more than a dozen papers, holds six US patents, and has given numerous invited talks.

You can find her online at She is giving an invited talk at the Optical Fiber Conference 2023.

Organisation: Coherent

Role: CTO

Based in: San Jose, California, USA

Education: PhD in Electrical Engineering, Stanford University; MS in Electrical Engineering, Stanford University; BS in Electrical Engineering, Caltech; BA in Physics, Bryn Mawr College

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