The idea of holographic storage dates back to the work of Polaroid researcher Pieter J. van Heerden in the early 1960s (and, some contend, to Nobel laureate Dennis Gabor’s original theory of holography in 1948). But the technology had never been practical, requiring exceedingly expensive materials and bulky laser setups – unlike the streamlined system from InPhase. Even Bill Wilson, InPhase’s chief scientist, was originally skeptical. In 1987, as a fresh PhD in physical chemistry from Stanford University, Wilson joined Bell Labs, turning down a job at IBM, where he would have started working on holographic storage. “I thought the field would be a complete waste of time,” he admits.
The turnaround began in the early 1990s, when IBM and other big players started to worry about the limitations of magnetic storage. As storage capacity increases, the magnetic grains that store data on a hard drive get packed closer together. Eventually, each grain’s magnetic field will begin to interfere with those of its neighbors, hindering their ability to reliably hold data. Engineers have thought of clever ways to defer this problem, but ultimately, grains in magnetic materials will be too dense to work properly.
Wilson recalls jumping into a friendly argument in the Bell Labs lunchroom about what new technology could eventually take the place of magnetic media – and the relative merits of holographic storage. At the time, the technique was undergoing something of a revival, being investigated by research groups at IBM, Polaroid, Caltech, and Stanford. Wilson and Kevin Curtis, an electrical engineer from Caltech who had recently joined Bell Labs, argued that holographic storage might actually become viable with suitably small and cheap optical components. In discussing the technical issues with their colleagues, they realized the key to making it viable was the material that stored the data.
In holographic storage, a “data beam” holding information is crossed with a “reference beam” to produce an interference pattern that’s recorded in a light-sensitive material. To retrieve data from a particular spot, a reference beam is shone onto it, and the combination of the reference beam and the patterned material reconstructs the original data beam, which is read by a digital-camera detector that translates the beam into a series of electrical signals. The recording material is typically either an inorganic crystal or a polymer. Polymers are more sensitive and require less powerful lasers, but they have their own flaws. For instance, when you hit a photosensitive polymer with a laser, it tends to deform, which messes up the data.
In 1994, a materials team at Bell Labs led by chemist Lisa Dhar worked with Wilson and Curtis to produce a “two-chemistry” photosensitive polymer. The researchers mixed one scaffoldlike polymer, which stayed rigid and preserved its structure, with another polymer that reacted to light and stored data. Decoupling the recording material’s optical and structural properties let the researchers fine-tune each independently, arriving at a combination of sensitivity and stability that had eluded previous efforts.
Over the next four years, the Bell Labs team got its holographic material to work in conjunction with the latest miniaturized lasers, cameras, and optical components to read and write data. This also required advances in software to correct for errors in storing and retrieving digital bits. In 1998, as a proof of concept, they built a prototype holographic recorder and recorded MP3 digital audio in real time. It was a bulky contraption and not particularly efficient. But at that point, says Wilson, “we realized we could build the darn thing.”
So in mid-2000, the researchers contacted Nelson Diaz about starting up a company. Diaz had made his name in the storage industry, working as an engineer for nearly 20 years at Digital Equipment Corporation and most recently as a general manager at StorageTek in Louisville, CO, a leading maker of disk and tape drives. When first told of the researchers’ focus on holographic storage, he was skeptical: he had heard the hype for years. But the closer he looked at the Bell Labs design, the more he believed. Five months later, he signed on as chief executive of InPhase.
The first order of business, says Diaz, was getting rights to the underlying intellectual property. InPhase negotiated a deal with Bell Labs that gave it ownership of the core patents for the holographic storage system. Then, of course, the company needed funding. In late 2000, before the tech bubble collapsed, InPhase raised $15 million in three weeks “without a business plan,” says Diaz. (Storage giant Imation was a first-round investor.) So in December 2000, six researchers from Bell Labs, including Wilson, Curtis, and Dhar, moved out of the suburbs of New Jersey and joined their new CEO in Colorado.