Another big step forward in GE’s holographic data storage program
If you have read the Technology section of today’s NY Times, or visited GE Reportsor Engadget, you will see that we are off to a pretty exciting start to 2009 on the Holographic Storage project so far. Earlier in 2008, we had demonstrated the threshold recording behavior in the new materials we are developing and we ended 2008 having demonstrated these materials using 405 nm blue lasers (the same wavelength used in Blu-ray Disc players). Now in 2009, we have taken yet another big step.
You may be asking, “what is threshold recording behavior?” Well, it is a fancy way of saying that we are looking to develop a material that records data in a way that is similar to how other optical disc technologies (CD, DVD, or BD) record data. That is, when the optical drive is reading a disc, the laser power is turned down to relatively low levels. To record data the laser power inside the drive will be turned up to high power. This high power enables the laser to create changes in the recording layer of the disc. For example, a laser power of 1 mW might be used to read a CD or DVD, which is less than most laser pointers generate, but a laser power of 10 to 50 mW might be used to record. So to put it simply, threshold behavior refers to the low-power readout and high-power recording process. However, this is where the similarities between the previous generations of optical storage and holographic storage end. In CDs, DVDs, or BDs, the recording is done by making marks (or changes) in a thin recording layer in the disc. These marks are typically made by changing the reflectivity of the recording layer – think of it as making microscopic damage spots in a mirror. In the case of holographic storage, we are creating chemical changes in microscopic patterns that will generate higher reflectivity when read by a low power laser – this is a more complicated process and requires that we create a material in which the refractive index can be changed when exposed to high laser power.
So returning to 2009, we started the year with materials in which we could write holograms using 405 nm blue lasers that gave at most 0.005% to 0.01% reflectivity. These materials demonstrated the high-power record and low-power readout behavior we were trying to create, but the patterns reflected too little light to enable high capacity on a disc. However, very recently, the team at GE has made dramatic improvements in the materials enabling significant increases in the amount of light that can be reflected by the holograms. In fact, just a couple of weeks ago, we demonstrated reflectivities as high as 1% in our materials using our holographic recording test setups. This represents a 100x to 200x improvement in performance. More importantly, the higher reflectivity indicates that when we scale the holograms down in size to those that would correspond to the marks created using standard DVD or Blu-ray optics, the reflectivities will be sufficient to enable the storage of up to 500 GB of data in a single CD-size disc. This is truly a breakthrough in the development of the materials that are so critical to ultimately bringing holographic storage to the everyday consumer.