The optical processing unit
Lot's of research is being conducted to find a solution for the limitations of traditional electronic CPU's. As we all know micro processors use a vast quantity of transistors (billions in the latests CPU's) to achieve their outstanding performance.
However we are seeing that this method is reaching it's limit's as the current architectures use almost less than 10 nm as the size of one transistor. Furthermore power consumption and heat build up also add to the limits of using billions of transistors crammed into a single chip.
We can already see how the traditional electronic CPU reached it's peak as no new break throughs or exponential increase in performance has been achieved in the last couple of years other than adding more cores per chip and increasing it's cache size.
It is evident that a new processing method must be developped to surpass the traditional electronic CPU performance.
As such new methods are being researched to achieve that objective, the most logic successor of electrons flowing through conductive materials would be light!
Light moves at -/+ 300.000 km/s and it has electromagnetic properties as it carries both an electric charge and a magnetic field!
But that's not the only advantage of light: it has other properties like reflection, transmission, absorption, refraction, diffraction, polarisation, ect... Furthermore light can be used in different wavelenghts corresponding with their frequency.
The potential for light to replace electric currents flowing through conductive materials is very real. Unlike electric current light doesn't need to be used in a closed circuit nor does it need a conductor for it's movement.
Using light instead of electronic circuits seems to be the next course of action when it comes to micro processors. However using light poses it's own dilemma: everything has to be reinvented!
There are already attempts at creating hybrids using light in fibreglass and a phaser array
to change it's wavelenghts. Such an invention already exists: The Enlight 256 of Lenslet.
Hybrids only use a fraction of the potential that light has to offer because it's integrated in traditional boards along with traditional electronic micro chips.
In this introduction I will present a concept of how light can be used as a substitute for electric currents! For this we have to take a look at the core of the micro processor: a Transistor. A modern CPU is a chip that incorporates billions of transistors to perform it's task.
So the first step is to analyze a transistor and outline it's primary funtion.
A transistor is made of semiconductor materials that can let the current flow completely, partially or block it so that no current flows at all. A small current applied to the base acts as a valve so to speak to conduct the current that goes through the transistor.
A transistor is used to create a low or high voltage whereby a low voltage symbolizes a 0 and a high voltage a I. Hence the binary system in logic gates: I and O. As such an output can be achieved following an input.
Transistors combined with other transistors and electronic components form the basis for creating and processing I - O / signals. This is the very basic fundamental of computing.
A microprocessor continually converts O - I signals. For example one byte is comprised of several bits: IIOOOIOO.
Before we go any further we need to take a look at logic gates to see how these I-O signals are converted.
We can see that each gate has it's own logic and thus it's own output signals. I will now use a concrete example of how this is achieved with transistors.
In the picture above 2 transistors are used to achieve an AND gate: here the combined current flow of both transistors gives a higher voltage or a positieve output signal I. If one of the transistors is not turned on the output signal is negative or O (low voltage).
So how can we build a working model using light as the carrier of the datastream? We need to find a way to have an output signal using a light beam as input signal.
The following concept is very straightforward and uses the following properties of light: absorption and reflection!
Absorption and reflection of light:
Concept of an input yielding a different output using light as the carrier.
Unlike a transistor the use of light as input can yield different output results: in the image above a white laser is reflected on colored mirrors. The colors that are absorbed can't be reflected anymore resulting in a seperate color being reflected. The contrast in the output can be read as a bar code of multtiple signals.(ex of such results in images below)
It should be noted that white reflectors completely reflect white light and black reflectors completely absorb white light this could be the basis of a NOT gate for example... (see image below) Transmission of light can also be used for other gates.
Let's take a look at an AND gate using a light beam:
As we have seen previously an AND gate consists of 2 transistors which give a logic 1 when both transistors conduct. (see truth table of logic gates in page 3) Here the same logic applies: if either one of the colored beams is missing the white light is not formed.
This proves that logic gates are possible using the properties of light it should also be noted that on the image above additive color mixing has been used (see the image below for more info)
The reflected light beams on colored mirrors give another color as result and those same results can be altered again with color mixing yielding again a different output!
Other results can be obtained by refracting light beams using lenses of different shapes. (see image below)
Refracting light makes it possible to change it's angle in this respect a light beam can be send in different directions it can be dispersed or recombined!
In the image below we can see an example of how light can be dispersed and recombined afterwords!
In the image below we can see an example of light diffraction: as light passes through a slit it forms waves which causes the light to have a variable intensity forming contrasts.
A single light beam can be split in many beams, it can reflected or refracted, it can be mixed with other colors to form new ones, it can be absorped or transmitted, it can bend if it travels through liquids, it can be polarized, it can be diffracted, it can be dispersed or recombined.
Light is very versatile and we haven't even brought the subject of it's electric charge or magnetic field in display. Light has also the properties of an electromagnetic wave!
The greatest advantage of an optical processor vs a traditional electronic CPU is that it can operate in a parallel mode instead of a serial! Serial processing is one stream of IOIOIOIOIOOOOIII signals at a time.
A parallel processor can operate many datastreams at the same time if we use all the properties of light to make a processing unit it would have a 3 dimensional shape comprised of thousands if not millions of sheets or layers on top of each other. A cube or a honeycombed 3d structure would be it's shape.
It's dataflow would be like a chain reaction rather than vast amounts of data through one channel.
This introduction is by no means finished: as I need to include a few other schematics and additional information to complete it.
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Or you can directly contact me.
Louis van Houttestraat 85
9050 Gentbrugge - Belgium
GSM: +32 477 56 18 54
Article created on 10 july 2017: it is subject to changes and updates!
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