02 Mar 2009
Holographic technology is on the brink of revolutionizing optical data storage and distribution. Kevin Curtis of InPhase tells Marie Freebody about the final push to market and why this technology could replace conventional magnetic and optical data storage.
Kevin Curtis is the chief technology officer and founder of InPhase Technologies. Curtis joined Bell Labs in 1994 to head up the technical group investigating holographic storage systems and media. Then in 2000 he founded InPhase, a start-up focused on commercializing the holographic technology developed at Bell Labs. To date, Curtis holds more than 50 US patents.
Can you explain the theory behind holographic data storage?
Holography breaks through the density limits of conventional storage by going beyond recording only on the surface to recording through the full depth of the medium. Unlike other technologies that record one data bit at a time, holography records and reads more than a million bits of data with a single flash of light. This enables significantly higher transfer rates than current optical storage devices.
High storage densities and fast transfer rates, combined with durable, reliable, low-cost media, mean that holography is poised to become a compelling choice for next-generation storage.
In addition, the flexibility of the technology allows a wide variety of holographic storage products to be developed, ranging from handheld devices for consumers to storage products for enterprises. Imagine having 50 hours of high-definition video on a single disc, 50,000 songs on a postage stamp, or 500,000 X-rays on a credit card.
How difficult is it to transfer this technology to the market?
It is extremely difficult to bring any storage product to the market as they are composed of very complex mechanisms and an investment of over $100 m (€78 m) is typically required to develop a new platform. To bring a first-of-a-kind storage product to market is even more difficult as you must deal with new suppliers and new tests have to be developed. This is why it has taken InPhase nearly eight years to develop its products even though it already had a lot of the basic technology from Bell Labs.
InPhase sells media and test equipment to more than 20 companies worldwide, with the majority being in Japan. The optical storage industry as a whole is researching holographic storage and about 50% of the papers at optical data storage conferences are now about holographic storage.
Why is data storage important and what are the main applications?
The consumer optical storage market for distributing content and archiving personal data is worth many tens of billions of dollars. After multi-layer Blu-ray Discs, which can store around 50 Gbyte, there is no other optical technology that can hit the capacities and transfer rates needed and can replicate CD and DVD media.
Long-term archival storage is a rapidly growing market worth around $5–6 bn and is important for businesses, which are required to store data for long time periods.
InPhase has sent out prototypes of its current long-term archival storage product, which stores 300 Gbyte and has a 20 Mbit/s transfer rate, and we expect to have qualified products towards the end of 2009.
We are working with a major Japanese company on a consumer version of the technology that is designed to allow backward compatibility with Blu-ray Discs. This is likely to take about five years since component development takes a long time.
We have also developed and demonstrated replication technology, which allows holographic media to be replicated by recording a whole virtual layer of the media at a time from a master. This is not limited to discs. We have developed a very small card reader (similar in size to flash memory drives) with several Japanese partners that would also read solid-state memory for mobile applications. Consumer applications of this include content distribution of videos, films and games in 3D and ultrahigh definition.
What is the most important recent advance and what hurdles remain?
Replication is an economic miracle that has allowed traditional optical storage to flourish even though its performance has not kept pace with magnetic storage. The two-step masters process that allows for replication of whole media at a time makes holographic storage fit into the same market space as traditional optical storage.
Holographic consumer products need to be very cheap in order to compete with DVD drives, which currently cost OEMs around $10 to produce. In order to bring the cost down, a lot of technology integration is needed.
What will the next breakthrough be?
Companies such as InPhase and Sony are researching homodyne detection, which is similar to heterodyne detection but with the same source. Currently, data is captured as a picture and is amplitude modulated. Homodyne detection is achieved by mixing in the laser with the reconstruction, which diminishes the effects of coherent noise as well as allowing for phase modulation. Detection improvements to the amplitude modulated channel are also likely.
• This article originally appeared in the March 2009 issue of Optics & Laser Europe magazine.
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