Table of Contents
Introduction 4
What are optical discs? 4
Why use optical discs? 5
The different generations of optical discs 5
Scope of this briefing 6
How 4G Optical discs are different 6
Current 4G Optical discs storage technologies and trends 7
The Protein Coated Optical disk technology 8
Why PCD and how does it work? 8
Possible benefits of PCD technology to organizations and users 8
Likely evolution and uptake of PCD Technology 9
Potentials PCD Technology 9
Feasibility of PCD Technology 9
Challenges faced by PCD Technology 9
Assessment of the impact of PCD for MOD 10
Recommendations 10
Conclusions 11
Introduction
Optical discs have been around for about 5 decades now and technologies around optical discs have been appearing ever since. Optical discs are very common today and play a vital role in storing all sorts of information digitally today. One of such optical disc technologies is the protein coated disc (PCD) technology which introduces optical discs with very high capacities. Here, optical discs are introduced, followed by the different generations of optical discs, then the protein coated discs in particular, the impact of PCD for ministry of defense (MOD), and then tries to conclude on PCD and how it may benefit the MOD.
What are optical discs?
In computing, an optical disc is a flat usually circular disc that acts as a storage medium for electronic data. Data is written to it and read from it using a laser beam or stamping machine. This is made possible by one or both of the surfaces of the discs being encoded with a special material. The encoding pattern on this surface follows a continuous, spiral path forming tracks that covering the entire disc. These tracks are further divided into sectors and contain the data stored in form of light and dark spots sometimes referred to as pits and lands (Read more: [1]). The diagram below shows how this surface is divided:
Why use optical discs?
Optical discs became the medium of choice as opposed to magnetic tapes and cassettes due their light weight, greater storage capacity, compact nature and their ability to store data digitally. Since the introduction of optical discs in the 1960s by David Gregg, there have been different kinds of optical discs used to store data/information.
The different generations of optical discs
The history of optical disc development is often referred to in reference to the different generations of optical discs. A generation normally refers to a timeline and the optical disc generations may be divided into four groups; the first, second, third and fourth. Each of the four generations is characterized by a major technological development that fundamentally changed the way they stored data. These different generations are looked at below.
A. First generation (1G) optical discs:
The first generation of optical discs developed between the 1960s and 1980s comprised of Compact Discs (CDs), Laserdiscs (LDs) and Magneto-optical discs (MDs). The CD is 12cm in size, is able to hold 700mb of data, and was invented in 1965 by James Russell. The LD varies in size from 12cm till 20cm and is able to record 30 minutes or 60 minutes of video per side of the disc while the MD was invented in early 1980s and also varies in size. The MD 130mn (5.25 in) is able to hold 128 megabytes till 2.3 gigabytes and the MD 90mm (3.5 in) disks able to hold 650 MB till 16.7 GB.
B. Second generation (2G) optical discs:
The second generation optical discs came after the first generation in the 90s and early 2000 and comprised of High capacity Mini Disc (Hi-MD), Digital Versatile Disc or Digital Video Disc (DVD), DVD-Audio, DualDisc, Digital Video Express (DIVX), Super Audio CD (SACD), Enhanced Versatile Disc (EVD), GD-ROM, Digital Multilayer Disk (DMD), DataPlay, Fluorescent Multilayer Disc (FMD), Phase-change Dual (PD) and Universal Media Disc (UMD). 2G optical discs generally store greater amounts of data, including broadcast-quality digital video. Such discs usually are read with a visible-light laser; the shorter wavelength of this laser and its other characteristics allow a narrower light beam, permitting smaller pits and lands in the disc leading to more data to be stored. (Read more: [1])
C. Third generation (3G) optical discs:
Third generation optical discs are currently being shipped (Blu-ray Disc (BD), High Definition DVD (HDDVD), and Professional Disc for DATA (PPD)) and in development (Forward Versatile Disc (FVD), Total HD disc, Versatile Multilayer Disc (VMD) and Ultra Density Optical (UDO)). 3G optical discs are meant for distributing high-definition video and support greater data storage capacities than 1G and 2G optical discs, accomplished with short-wavelength visible-light lasers and greater numerical apertures. The Blu-ray disc for example uses blue-violet lasers and focusing optics of greater aperture, for use with discs with smaller pits and lands. They can store from 25GB to 50GB of data.
D. Fourth generation (4G) optical discs:
4G optical discs are currently being researched and prototyped. They have the potential to hold more than 1TB of data. They currently comprise of; Tapestry Media, Holographic Versatile Disc (HVD) and Protein-Coated disc (PCD).
Scope of this briefing
This paper attempts at giving a brief overview of 4G optical discs technologies, and an introduction to protein coated disk technology in particular, its potential, likely adoption and evolution, how the MOD may benefit from it and recommendations for actions the MOD may want to take with respect to it (PCD) appearing on the scene. It does not attempt to go into the technical details of the PCD technology since it sole purpose is to draw interest and highlight its potential.
How 4G Optical discs are different
Over the years, optical storage density has been increased in the first 3 generations by shortening the wavelength of light used to read and write however fourth generation optical discs have deviated from the trend by not going in for shorter wavelength lasers but for a variety of large-capacity optical disc technologies including near-field recording, supper-resolution, recording, multilayer recording and holographic data storage. The following section list and describes the current 4G optical discs technologies.
Current 4G Optical discs storage technologies and trends
Current 4G Optical discs storage technologies include the following:
I. Holographic Versatile Disc (HVD):
The HVD is an optical disc technology developed around mid-2008 that can store up to several terabytes of data on an optical disc the same size as a CD, DVD, or Blu-ray disc. It employs a method called collinear holography, whereby green and red laser beams are collimated in a single beam.
II. Layer Selection Recordable (LS-R) :
LS-R optical disc technology allows much larger data storage densities than 3G optical discs by allowing the use of a large number of data layers in a single disc. In previous optical storage technologies, interference and reflections between layers made it difficult to produce discs with many different data layers.
III. Protein Coated Disc (PCD):
PCD is a theoretical optical disc technology currently being developed. It entails covering a regular DVD with a special light-sensitive protein, which would in theory permit storage of up to 50 Terabytes on one disc. We are going to look at this technology in more detail in the next section.
IV. 3D Optical data storage:
Different approaches to 3D optical storage are still being investigated in countries like the USA and Japan. These consist of the extension of present disc systems to a layered format, and 3D layered disc systems. The layered 3D optical storage is a normal extension of current optical disc systems with a potential to increase the media capacity without notably affecting the cost of the drives. Multi-layer recording extends the efficient areal recording density and capacity per disc. It therefore enables the infiltration of new markets with technologies.
The Protein Coated Optical disk technology
Why PCD and how does it work?
This idea was presented at the International Conference on Nanoscience and Nanotechnology in Brisbane in July 2006. Developed by Professor V. Renugopalakrishnan and colleagues, the protein coated disc technology unlike other optical technologies coats the disc with thousands of light activated proteins called bacteriorhodopsin (BR) which temporarily convert to a series of intermediate molecules when exposed to sun light and can withstand temperatures as high as 140C and pressures above 300GPa. This property allows the proteins to act as individual bits capable of representing or storing digital signals (1s and 0s) and ideal candidates for protein based building blocks for future electronic devices. However since the molecules have a tendency to return to their original state after a short period, Renugopalakrishnan and his colleagues have modified the required microbes’ DNA to create proteins capable of remaining in that intermediate state for several years. So if the ground state is taken to represent 0 and the intermediate taken to represent 1 and can be kept in this state for years then we have digital storage medium. The resultant protein based disc will have advantages over current optical storage technologies because data will be stored in proteins that are only a few nanometers (about 2nm) across. This is far smaller than the size of current pits and lands on discs today. For more details on this technology [3].
Possible benefits of PCD technology to organizations and users
With the demand for greater data density storage and memory devices growing exponentially, particularly with the ever-increasing use and explosive growth of broadband communication, Internet, increasingly complex multimedia mobile devices, and rapid expansion of on-demand databases serving multinational businesses PCD technology would benefit users and organizations alike if commercialized by allowing for a range of large capacity storage devices with unparallel data access rates. This seems obvious as one looks around at proposals and other technologies coming up for example standards for Ultra High Definition Television currently proposed by BBC, SH and RAI with data size of about 194GB/min.
Likely evolution and uptake of PCD Technology
Potentials PCD Technology
This technology was being developed and looked into by Renugopalakrishnan’s team and a Japanese corporation called NEC. NEC is a global company with a net income of about ¥110.267 billion. The PCD technology has the potential of recording higher densities and rates than other optical disc technologies , high durability against environmental conditions, high life-time for storage and by-passing the basic limit to the laws of scaling(Read More [2]) currently plaguing today’s storage technologies. It may also leap frog advances in electronics and could be used for devices for fast non destructive optical processing. With the potential of providing 2D protein based storage, it could relatively be cheaper than other 3D recording technologies that are usually more complex and bulky.
Feasibility of PCD Technology
With respect to feasibility, there is a possibility for cost-effective mass production through genetic engineering advances to increase the lifetime of the states (1 or 0). There also is the possibility of achieving data transfer rates of a few picoseconds. These data rates are far beyond the limits of competing technologies. There are also currently different ways to implement read and write mechanisms in protein disc recording and conventional methods employed to track the position of bits in today’s magnetic and optic drives could be used for the reading mechanism in protein coated discs. All these made this technology a feasible venture and it had a lot of positive feedback from the media, researchers and scientists. However, it is very less likely that the standards for today’s optical technology would suite PCD technology.
Challenges faced by PCD Technology
Despite what has been said so far, two main challenges face PCD implementation these are: the development of thin overcoats that would protect the protein films from environment and ensure adequate lifetime of the memory device; and the technology to provide adequate power in a nano scale beam spot for read and writes. However, Renugopalakrishnan’s team and NEC have succeeded in creating a prototype for such a disc, they think it can be used for hard drives and USB drives for the future.
Today, work on PCD technology has been abandoned with no clear reason for this given by the media or researchers.
Assessment of the impact of PCD for MOD
In the military, current and future operations rely increasingly on the timely capture, processing, delivery and storage of accurate actionable information. This calls for innovative information storage solutions delivering increased speed, security and capacity. With this current state of affairs, PCD technology provides itself as a candidate of choice for militaries wanting to address these issues.
According to the MOD most of the data it works with falls under the category of “big data” (a catch-phrase, used to depict a massive volume of data or information that is so large that it is difficult to process using traditional software and database techniques). Challenges currently faced with such data include capture, curation, storage, search, sharing, transfer, analysis, and visualization. Despite these challenges, the MOD appears to have never made mention of PCD in any of its documents or strategies. PCD data rates and capacity would go a long way in solving these problems as we have seen so far. The argument of the MOD and others in the industry may be that, this technology is not yet mature and putting money into it in the form of grants or tabs may be a risk not worth taking at this time. However with a working prototype already it is very possible it will mature by the next decade. Another area where the MOD recently got interested in is cloud technology and running their own cloud service is critical due to the sensitive nature and security requirements they require. For such a service to be delivered successfully, the importance of large storage capabilities and impeccable transfer rates cannot be overstated.
Recommendations
With the MOD expressing the need to identifying emerging technologies it is recommended that this trend in identifying and evaluating the potential benefits of particular technologies continue. It may be necessary for the MOD to setup a technology review committee to look at technologies that had been sidelined in the past because they did not show potential but in such a dynamic world the situation may have changed. It should also put in place a response strategy for course of action if a technology’s situation has changed and needs further looking into. In the case of PCD in particular, it should also give grants or fund further research that may lead to its feasibility, revival and production if need be.
Conclusions
Irrespective of it being abandoned as at now, the PCD has brought some great ideas to the optical disc technology platform and should be looked further into. If the PCD became practical, it would have great impact on storage technologies and the MOD in particular and its future ventures. It is also very likely that the MOD would find other implementations of it with time. For these reasons, it makes sense for the MOD to have another look at PCD and if possible invest in further research.
References
[1] http://www.lintech.org/comp-per/12OPDISK.pdf
[2] http://www.av8n.com/physics/scaling.htm
[3] Protein-Based Disk Recording at Areal Densities beyond 10 Terabits/in.2 http://www.northeastern.edu/bionano/bio-pdfs/MRS_Sep08_Khizroev_MRS.pdf
