Optical data encryption techniques provide a high level of security because there are many degrees of freedom with which to encode the information, such as amplitude, phase, wavelength, and polarization. To protect the stored information it is required to encrypt the data.
Magnetic disc data storage is replaced with optical data storage. Data access times for magnetic discs are currently exceedingly sluggish when compared to the speed at which CPUs execute instructions, therefore any increase in data access speeds will considerably expand the capabilities of computers, particularly when dealing with huge data and multimedia files.
Optical memory is a technique that stores data on a three-dimensional medium and can access it one page at a time rather than sequentially, resulting in higher storage density and access speed. Optical data storage technologies are on the verge of becoming cost-effective. Experimental optical data storage devices have successfully exploited photo-refractive crystals and photopolymers.
These systems take advantage of the photosensitive materials’ optical capabilities, as well as the behaviour of laser light when employed to record an image of an object.
In terms of data access times, data transfer rates, and data storage density, optical memory falls between between main memory and magnetic disc. Data storage has failed to close the gap while CPUs and buses generally double their data capacity every three years (Moore’ slaw).
Every millisecond, CPUs execute one instruction, which is six orders of magnitude faster than a single magnetic disc access. The applications that computers are used for grow together with the computer. Large binary files comprising sound or image data have recently become ubiquitous, resulting in a significant increase in the demand for high-capacity data storage and access.
To handle these enormous files fast and efficiently, a new high capacity form of data storage must be devised.
Optical memory is also known as a holographic memory system since it exploits the basic principles of holography for recording purposes. Because it is a genuine three-dimensional storage system, data may be retrieved a complete page at a time rather than sequentially, and there are few moving parts, mechanical motion limits are minimised, optical memory is a promising technique for data storage.
The interference patterns of a reference beam and a signal beam of coherent light are recorded using a photosensitive material, where the signal beam is reflected off of an object or includes data in the form of bright and dark patches.
The photosensitive material is designed in such a way that the recorded interference pattern may be replicated by shining a beam of light on it that is identical to the reference beam. The resultant light will take on the recorded interference pattern and be collected on a laser detector array that covers the whole surface of the holographic medium.
Changing the angle or wavelength of the incident light allows many holograms to be recorded in the same region. This method allows you to access a whole page of data. Optical memory techniques are currently on the verge of becoming technologically and economically viable.
The recording rate, pixel sizes, laser output power, hologram degradation during access, temporal decay of holograms, and sensitivity of recording materials are the key roadblocks to implementing optical data storage.
This could become a viable alternative to magnetic disc in the near future, with a total cost of between $161 and $236 for a comprehensive optical memory system.
Data security may be done via optical technology, which can assist solve the problem of huge data storage and quick data transfer in a variety of methods. We are familiar with two-dimensional data storage in the form of DVD and CD, in which data is stored as a hologram on a photosensitive crystal by illuminating the interference pattern generated by an object and a reference beam. Multiple photos can be stored in the same location, increasing the capacity.
Data is the fundamental building material on which the entire structure is built. In the real world, everyone works together under the assumption that their data is safe. The encryption techniques used by Optical Data Security provide a high level of security.
It provides several degrees of freedom, like as amplitude, phase, wavelength, and polarisation, that can be used to encode information. As a result, encryption becomes a critical component for protecting data from malicious software. The encryption here means that key codes change the original data into stationary white-noise data, and unauthorised users can’t get the original data without knowing the key code.
Even our everyday programmes, such as Sapp, have the feature of End to End Encryption. This sort of encryption provides a high level of security because only the sender and recipient are able to read the exact message.
Using various encryption techniques, original data can be optically encoded. Some of the most common encryption techniques accessible today are double random phase encryption, three-dimensional position encryption, and wavelength-code encryption.
Optical data storage principle
Holography is the fundamental basis of optical data storage. Deni Gabour invented holography in 1948. The holographic method was a two-step coherent picture formation process in which a record of the interference pattern created by the interaction of the waves diffracted by the object and a coherent background or reference wave was made. The original wave front is rebuilt when this hologram is lit. As a result, we get a three-dimensional image of the original diffracting item.
When two light beams interact in space, one from the object whose picture is to be captured and the other from a reference beam, an interference pattern of alternate bright and dark fringes is formed, as shown in the diagram.
When a photosensitive material or medium is placed at the interference location, the interference patterns are recorded on the material as a change in refractive index or absorption characteristic. The reference beam alone is now made to be incident on the photosensitive material in order to regenerate the original beam, i.e. the source beam from the item.
This beam is then diffracted within the material’s structure, replicating the original beam. This is the fundamental principle for recording and reading data in the case of optical storage system.
Simple Components
The data storage and retrieval processes of an optical data storage system necessitate the use of specific materials. The following are critical components for optical data storage:
1.LASER
2.Mirrors and Lenses
3.Modulators of spatial light (SLM)
4. Materials that are photosensitive
Photorefractive crystals
4.2.Photopolymers
5.Devices that are Charge Coupled (CCD)
6.Encryption phase masks
LASER
LASER stands for light amplification by stimulated emission of radiation. A laser is an electronic device that emits coherent, almost monochromatic, and highly directed electromagnetic radiation with wavelengths ranging from sub-millimeter to ultraviolet and X-ray. More than 200 different types of lasers have been created, ranging in power, size, performance, application, and price. The basic characteristics of a laser are directionality and monochromatic.
It’s suitable for optical recording because of these characteristics. Argon ion lasers, krypton lasers, and diode lasers are commonly employed to record holograms on crystals.
Mirrors and Lenses
Laser beams are reflected using mirrors in the desired direction. The laser is usually converged to a point using lenses. In the case of opticalrecording, a specific lens known as a Fourier lens is utilised.
Modulators of Spatial Light (SLM)
The SLM is an optical device that converts a real image or data into a single light beam that intersects with the reference beam during recording. It is made up of a series of pixels, which are often minuscule shutters or LCD screens. A computer can be used to control these.
The SLM receives binary data from the computer. A bit of data corresponds to each pixel of the SLM. So, depending on whether the bit is a 1 or a 0, the pixel in an LCD will be dark or transparent, or open or closed in the case of microscopic shutters.
Devices that are Charge Coupled (CCD)
By far the most popular technique for translating optical pictures to electrical impulses is the charge-coupled device. CCDs are silicon devices with a variety of potential wells produced by a number of columns and implants (for vertical confinement).
A CCD is a silicon-based semiconductor that is structured as an array of photosensitive components, each of which creates photoelectrons and stores them in a little bucket of charge called potentialwells. Each pixel is usually 15 to 30 m2 in size. With a dimension of about 25mm square, current CCDs have formats or resolutions better than 2048 * 2048 pixels
Encryption Methodologies
Encryption techniques come in a variety of shapes and sizes. Three main encryption techniques are explained in this article. They are as follows:
1.Dual Random Phase Encryption for Encrypted Memory
2.Fresnel Domain Encrypted Memory Using Three-Dimensional Keys
3.Wavelength-Code and Random Phase Masks for Encrypted Memory
4. Double Random Phase Encryption for Encrypted Memory
Application
Insecure communication networks using ultra short pulses can use encrypted memory with double random phase encryption. The original data is saved in an encrypted memory system in this system. The space to time converter converts the encrypted data read from the memory into a one-dimensional temporal pulse, which is subsequently sent over optical fibres.
The time to space converter at the receivers converts the temporal signal back into a spatial signal. The data can be decrypted by authorised users using the right key. This system is intended to communicate at a rate of more than 1 terabit per second.
Conclusion
This paper discusses three encrypted optical memory devices. These systems are safe because the multidimensional keys, which are made up of two-dimensional phase masks, their three-dimensional coordinates, and light wavelengths, have a huge number of mathematical possibilities. The outcomes of the trial are quite positive. The encrypted memory system is intended to play a key role in ultra-fast secure communication systems that use spatial temporal converters with ultra-short pulses to enable communication at speeds exceeding Tb/s.
The recent commercial availability of system components, combined with significant advances in recording media, recording methods, and demonstrated densities of > 30 channel Gbits/in2, are thought to remove many of the barriers that previously prevented the practical consideration of optical data storage and greatly improve the prospects for Hollography to become a next-generation storage technology.
