Long before Sanjai Parthasarathi had to explain a global photonics company, he had to understand an interface. In the 1990s, his technical work examined the place where a thin film meets a substrate, a boundary so slight that its integrity could determine whether a coating held or failed. He studied nondestructive ways to see what ordinary inspection missed. He worked on ultrasonic measurement in manufacturing. He was named on patents, including one that used optical behavior to measure the spacing between surfaces.
It is tempting to treat this as a prologue he later left behind. It makes more sense as the operating system for everything that followed. Parthasarathi's career has moved through research, manufacturing, product management, business operations, strategy, and marketing. Each job changed the scale of the interface. The early question was how one material met another. The later questions became how a product met a market, how an acquired company met its new parent, and how a portfolio dense with physics met an audience that needed a reason to care.
Now Chief Marketing Officer of Coherent Corp., he works on an unusually difficult corporate sentence. Coherent makes engineered materials, lasers, optical components, transceivers, switches, sensors, and systems. Its products operate inside data centers, communications networks, factories, research instruments, cars, and consumer devices. Much of what it sells is essential and largely invisible. The buyer may know the component intimately. The public usually sees only the application it enables.
The engineer does not disappear
Parthasarathi trained as a mechanical engineer at IIT Madras, then earned a master's degree in mechanical and aerospace engineering at the University of Virginia and a doctorate in engineering science at Penn State. He later completed executive education at Stanford. The sequence matters because his marketing voice is built less around persuasion than decomposition. Faced with a complicated system, he looks for its functions.
His career before Coherent's predecessor included Concurrent Technologies Corporation, Western Digital, TeraStor, Oplink Communications, Avanex, and Oclaro. The industries shifted from coatings and data storage to optical networking. The work moved from technical development toward product lines and customers. By 2009 he was Senior Director of Product Line Management at Oclaro. In 2013 he joined II-VI, where he became Vice President of Product Marketing and Strategy for photonics in 2015.
“It's ultimately about taking the technology and taking the story and crystallizing it for the audience.”Sanjai Parthasarathi
Crystallizing is a revealing verb for someone formed by materials and measurement. It suggests structure, not gloss. A useful technical story preserves enough of the original substance to remain true. It simply gives that substance a shape another person can hold.
Two customers walk into a strategy meeting
When Parthasarathi became II-VI's first CMO in 2019, he expected the opening conversation to be about conventional segmentation. Instead, he remembers receiving a sharper instruction. The company had two kinds of customers: people who bought its products and people who bought its stock.
The line expanded the assignment. A product customer might ask about performance, reliability, roadmaps, price, or supply. An investor might ask why materials, components, and systems belong under one roof, how an acquisition creates value, or where the next period of growth will come from. Both audiences need technical accuracy. They do not need the same tour.
That became more consequential almost immediately. II-VI completed its roughly $3 billion acquisition of Finisar in 2019, adding scale in optical communications. In 2022 it acquired the laser company Coherent in a deal valued around $7 billion. The combined business adopted the Coherent name in 2023. Parthasarathi has described reorganizing marketing around markets, creating corporate strategic marketing and intelligence functions, and building a more centralized operating model for the story.
A complicated company does not need one generic message. It needs one truthful system with different entrances for customers, investors, suppliers, and employees.
The public-facing compression is elegant. At the most fundamental level, Coherent generates photons, modulates them, amplifies them, directs them, and detects them. At the application level, Parthasarathi reduces nearly everything to three jobs: transmit data, modify materials, and sense and measure. These are not slogans pasted over the portfolio. They are a map through it.
Light enters the AI rack
The map is especially useful in the current data-center buildout. AI systems join large numbers of processors that must exchange huge amounts of information while contending with distance, power, heat, and physical space. Optical links already carry traffic between racks and out of data-center buildings. The next contested boundary is inside the rack, where electrical connections have historically dominated.
Parthasarathi puts the physics plainly: when data has to travel fast and over longer distances, it has to go optical. He describes the network in three dimensions. Scale-out connects clusters, often across racks. Scale-up connects processors more tightly within a system. Scale-across links data centers and longer-reach networks. The distinctions turn an abstract AI boom into specific engineering demands for transceivers, lasers, switching, packaging, amplification, and thermal management.
His argument returns repeatedly to vertical integration. Coherent can work from materials and semiconductor devices through components and subsystems, and in some markets all the way to complete laser systems. That breadth can look unwieldy on an organization chart. In his telling, it becomes useful when customer roadmaps, manufacturing capacity, and supply resilience have to move together.
He also insists that Coherent is, at heart, a materials company. The remark pulls a futuristic AI conversation back toward furnaces, wafers, crystals, coatings, and the physical limits of fabrication. The future may arrive as an optical circuit switch or a faster transceiver. It still depends on controlling matter with remarkable precision.
A boundary for the machine
Parthasarathi's position on generative AI is similarly grounded. Coherent uses AI for content generation and demand creation, and its industrial systems can use machine learning in processes such as seam tracking. But he draws a clear boundary around the strategic work. “AI is not going to tell me a story that has not been written yet,” he has said. Marketers write the story; AI helps refine it.
For technical marketers, this is less a defense of craft than a description of where original information lives. A model can reorganize what has already been expressed. It cannot independently absorb an unpublished customer roadmap, weigh a manufacturing constraint, interpret a shift in capital spending, and decide which opportunity the company should pursue. That synthesis still belongs to people close to the market and the technology.
“AI is not going to tell me a story that has not been written yet.”Sanjai Parthasarathi
The claim fits his own path. His authority as a marketer comes from having occupied so many positions around the object being marketed. He has seen how products are researched, made, managed, and sold. He has had to explain them during acquisitions and a rebrand. He has spoken to engineers at photonics conferences, investors at company briefings, and marketers at leadership events. Each audience changes the framing, but not the underlying system.
The interfaces keep widening
His work now extends beyond the CMO role. Public biographies list advisory positions with CloudPhotonix, Ideal Power, and L&T Semiconductor Technologies, along with service on Penn State's Industrial and Professional Advisory Council. In 2026 he joined BayAreaCMO's founding advisory board and became an advisor to CloudPhotonix. Coherent's annual report also records his participation as a mentor in the CEO Action Mentoring Initiative during fiscal 2024.
In 2023, he appeared at IIT Madras Research Park for the signing of an agreement to establish a Coherent center of excellence there. The scene forms a neat loop: the engineering school where he began became a place where his employer would invest in a new bridge between industry and research.
His public posts tend to return credit to teams. After OFC 2026, he thanked the Coherent group whose work made the event successful. After a company leadership gathering later that year, he wrote about alignment, execution, and the expertise across the organization. The language is consistent with his wider thesis. Technical advantage comes from coordination across layers. So does the story of that advantage.
A career that started by examining microscopic interfaces has arrived at much larger ones: electricity and light, research and industry, acquired businesses and a shared identity, human insight and machine assistance. Parthasarathi's recurring move is to make the boundary visible, then clarify what must cross it. Sometimes that is a photon. Sometimes it is trust. Often it is an idea that has to travel intact.