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REVIEW OF INNOVATIVE TRENDS IN OPTICAL DEVICES - DIGITAL INFORMATION STORAGE AND ITS LOGICAL EXTENSION - OPTICAL MEMORY DEVICE

2012-03-11
Andrew (Gabriel) Livshits

Recently, this subject is given enough attention;
It is very easy to follow scientific publications;

For example, a group of Japanese physicists has created a workable optical memory with a record-low power consumption. The article appeared in the scientific journal Nature Photonics.
Creating a computer that would use instead of electrical pulses optical signals - the so-called optical computer - is an area where active research (recently, for example, was first established passive optical diode). In the new work, scientists engaged in the creation of an optical memory.

The physical memory is a photonic crystal, we have a body in which the refractive index varies periodically.

We used crystals of an alloy of indium and phosphorus with a cavity within which the particle with the addition of a crystal of gallium and arsenic. Particle represents a single bit of memory, while the surrounding crystal fiber is used and the heat sink.

Total scientists managed to get four bits of memory. According to our tests, this bit is capable of storing data on a single charge for about 10 seconds (in the old system, the figure was about 250 nanoseconds).
In addition, the resulting memory consumes about 25 nano-watts, which is several orders of magnitude less than in similar devices.

The main drawback of the new memory is a relatively long time recording.
Search in progress, and that's not long to wait for a new post:
... Scientists and Purdue University have created a passive optical diode based on silicon. It is reported by Discovery News. The article appeared in the scientific journal Science.
The diode is a pair of rings on the silicon substrate of silicon dioxide. The linear dimensions of the device - the order of ten micrometers.
The diode operates in a way that transmits infrared photons in one direction, but does not let them in the opposite direction. According to scientists, their device can be made much smaller than it is now, that will significantly contribute to miniaturization.

According to scientists, they created the diode is classified as passive devices, it is not able to change the properties under the influence of a signal. However, according to scientists, despite the serious use of nonlinear effects in the design of the proposed device can be produced on existing equipment.

At the present time are being developed to create computers that would use in photons instead of electrons. It is believed that such devices will not only be smaller and faster than existing, but will eliminate the need to convert optical signals into electrical and vice versa (this is happening now because of the wide spread of fiber-optic communications).

In August 2011, scientists from the University of California announced that they have managed to create an optical diode based on linear material, without the use of complex optical effects.
Also in 2009 a paper appeared in Nature, the authors describe a microwave diode based nano- dowels.

In addition, physicists have created a microwave diode - a device capable of transmitting electromagnetic radiation of the microwave spectrum in one direction only, reports New Scientist. Article published in the scientific journal Nature.

As part of the researchers were interested in the passage of microwaves through a forest of semiconductor nano- dowels.

Wood was a photonic crystal - a material with a band-gap frequency (similar to the band-gap semiconductors). If such an incident photon with the crystal frequency gap, it is reflected from the surface.
Nano-les was placed in a strong magnetic field. As a result, it became clear that the motion in one direction, wave interaction with a crystal leads to their maturity. In the opposite direction the waves are moving quite freely.
According to the researchers, the new technology would theoretically create computers that transmit information will be performing photons.
This will greatly speed up your computers. In addition, scientists plan to improve its diode, so that he was fit for work in the optical range.

But the problems with heating and disproportionate loss of energy for heating continue to prevent developers and here's how to order, most recently, Japanese scientists succeeded in creating a thermal diode - a device that can pass the heat in one direction only.

According to the researchers, the new device can be widely used, for example, to create cooling systems for CPUs.
Physicists have also created and acoustic diode - a device capable of acoustic waves to pass in one direction only.
The diode has been realized so far only in theory - practical tests, researchers have not performed. The article appears in the Journal of physics Physical Review Letters, and her summary of the results in the publication Physical Review Focus.

It is assumed that the new device will consist of two layers. The first is the so-called "non-linear acoustic" stuff. Propagating acoustic wave creates variations in pressure, and in such a material pressure distribution determines the velocity of propagation of sound waves.
Passing through the "non-linear acoustic" stuff, creating a wave of so-called secondary fluctuations, some of which are double-wave relative to the original frequency.
The second layer in the diode, in turn, is made from a material that can be held only that the most waves with twice the frequency.

The scheme of the device is as follows. The waves emitted by the source, you first get into the "non-linear acoustic" environment, thus causing secondary oscillations with double frequency.
All but the last layer are blocked by the filtering. On the other hand the wave going to the source (ie in the opposite direction) is also trapped by the filter.

By choosing the parameters of materials in a special way, physicists have achieved that amount of energy transported in the direction of the source, about 100,000 times the amount of energy returning to the source.
The new device has several major drawbacks.
First, it only works for a fairly narrow range of frequencies.
Secondly, the frequency at the output is twice the frequency differs from the input.
Third, the double-frequency wave can take place both in forward and backward.

The last drawback - the lack of practical testing of new concepts.
According to the researchers, these devices will be extremely popular. For example, in medicine, ultrasound machines are used. At the same time the very source of ultrasound in such a device is not protected from returning waves that can make a disturbance in his work.

The presence of the device with a transmission capacity to allow one-way to solve this problem.
And here is absolutely appropriate to recall the actual development of optical systems that can save a huge amount of information in case they do multilayer
In many ways, the reality of building such of optical bodies made in the form of disks is dependent on compliance and technological aspects of the possible construction of a multi-layer disc with a consistent method of polymerization of lamellar

These are the considerations:

A. Cycle of the production line. Duration of technological transitions.

  • Transportation from the previous disk blanks working position on the next working position, the duration of the transition, 3 seconds;
  • Installation, clamp the desktop position - 1 second, pause, 2 seconds, during which all the elements of the position given in the operating position;
  • Applying a liquid agent total time of 3 seconds, the installation of these jets is moving multi-torch 2 seconds, lasts for a second application, removal of multi-torch jets from the workspace requires 2 seconds, to blow the hot gas is required 1 second;
  • Polymerization process requires a total time of 6 seconds of them on the carts must-emitting display for 2 seconds, directly on the heat treatment is necessary, 2 seconds, the removal of the radiating screen takes 2 seconds;
  • The application of marking symbols is the total time is -6 seconds of them on carts, orientation and vacuum clamping the mask requires -2 second;

Exposure to the need, 2 seconds, to remove the mask from the working volume of the working position requires 2 seconds;

From the foregoing it is clear that the duty cycle (cycle) production line should be equal to 3 seconds, for the duration of the operation hits in 6 seconds, the line should be provided for two parallel working position.

Two. On the thickness of the layer (s) of optical material, grown for one full production cycle.

  • For one production cycle must be applied to three optical layers, one of these layers, which is located between two other layers - should be made of light sensitive material and its thickness must be within 0.002 mm, limiting it to two sides of the layers of optically transparent material should be each have a thickness of 0.005 mm, total thickness of this structure with three layers of - 0.012 mm;

The first advantage of the proposed technology is that these thicknesses can, if necessary, be changed without any changes in design and manufacturing equipment line-up and using the same tools and equipment;
The second advantage is that even within a single disk, you can change the thickness of the layers or layer groups, taking into account various additional conditions and requirements, the system can be combinations of layer thicknesses, for example, allow to enter a special code for the geometric volume of protection of information provided in the disk.

Three. On the question of the accuracy and geometric proportions between the elements and the surfaces of disks made of the proposed technology.

  • Refers to the interconnected system of dimensional parameters and their tolerances, their mutual influence and impact on other dimensional parameters of disks in the manufacture of multilayer disc technology for the proposed average accuracy of all its elements, subject to the following conditions:

a) the accuracy of the table working position;
b) the accuracy of the orientation of the disk relative to the position of the working table;
c) the ratio of precision manufacturing and assembly tables and other elements of the working position;
d) the accuracy of weight and volume parameters of the dose of material that is applied to the surface of the disc;
e) the uniformity of distribution of material on the surface of the disk;
g) Depending on the uniformity of the different effects on the disc and its elements in the manufacturing process, referred to as linear and to surround parameters (including the effects of temperature variations);
h) the accuracy and homogeneity of the chemical composition of materials used;
i) the accuracy of dosing materials and precision ratio (weight and volume), the dissolution of alloying elements in the base material;
a) the accuracy of dosing and dissolving the catalysts in the base material;

4. More information is needed

  • Comparative analysis of the contact between the mask and the projection mask. Contact mask is applied to engineering and technology consistent layered growth of the optical disk of the body has the following advantages over the projection mask:

a) its use does not require complex optical projection systems;
b) its use does not require high-precision positioning of the equipment units;
c) the cost of manufacturing a contact mask is much lower;
d) operating costs significantly below the contact mask;
d) the required accuracy of manufacturing a contact mask is much lower;
e) The mechanical strength and wear resistance of the contact mask is much higher;
g) the contact mask with a clip to disk fixes its geometry;
h) using a contact mask is no need for complicated masks, and adjustment of the coordinates of the disc in the process of identification and relative orientation;
s) through the use of metal coatings lifespan of the mask is large enough, specifies that a more efficient use of resources spent on its production;
a) due to the fact that the contact mask has a polished contact surface on which the deposited metal coating, the adhesion to the polymer layer has a very low level;
l) contact mask has a high working accuracy, since its vacuum pressing to drive the air gap is eliminated

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