Optical Computers

[steve_bank]

One problem is at some point photons have to interact with electronics.

Optical computing - Wikipedia

en.wikipedia.org

Optical computing or photonic computing uses light waves produced by lasers or incoherent sources for data processing, data storage or data communication for computing. For decades, photons have shown promise to enable a higher bandwidth than the electrons used in conventional computers (see optical fibers).

Most research projects focus on replacing current computer components with optical equivalents, resulting in an optical digital computer system processing binary data. This approach appears to offer the best short-term prospects for commercial optical computing, since optical components could be integrated into traditional computers to produce an optical-electronic hybrid. However, optoelectronic devices consume 30% of their energy converting electronic energy into photons and back; this conversion also slows the transmission of messages. All-optical computers eliminate the need for optical-electrical-optical (OEO) conversions, thus reducing electrical power consumption.[1]

Application-specific devices, such as synthetic-aperture radar (SAR) and optical correlators, have been designed to use the principles of optical computing. Correlators can be used, for example, to detect and track objects,[2] and to classify serial time-domain optical data.[3]

Controversy

There are some disagreements between researchers about the future capabilities of optical computers; whether or not they may be able to compete with semiconductor-based electronic computers in terms of speed, power consumption, cost, and size is an open question. Critics note that[9] real-world logic systems require "logic-level restoration, cascadability, fan-out and input–output isolation", all of which are currently provided by electronic transistors at low cost, low power, and high speed. For optical logic to be competitive beyond a few niche applications, major breakthroughs in non-linear optical device technology would be required, or perhaps a change in the nature of computing itself.[10]

 

[lpetrich]

Optical computing: the power of light

Advantages of optical computing:

• Fast density; small size; minimal junction heating; high speed; dynamic scaling and reconfigurability into smaller/larger networks/topologies; vast parallel computing capability, and AI applications.
• Not prone to electrical short circuits and immune to electromagnetic interference.
• Provides low-loss transmission and a lot of bandwidth, so multiple channels can communicate simultaneously.
• Data processing on optical components is less expensive and simpler than data processing on electronic components.
• Photons are able to pass across one another.
• Optical materials are more accessible and have higher storage desnity than magnetic materials.

The disadvantages are:

• It’s hard to develop photonic crystals.
• Due to the interaction of several signals, computation is a complex process.
• Current optical computer prototypes are bulky.

Photonic crystals? That's for making photonic switches, a photonic counterpart of transistors. It's a crystal with nonlinear response that will darken if one shines light on it from one direction -- a direction that must be different from the direction of the light that the crystal will be controlling.

One can get around that difficulty by using some intermediate, like doing light - electronics - light, but that's more complicated.

 

[lpetrich]

Optical computing is good for artificial neural networks, because they can do matrix-vector multiplication very fast. They may also be good for applications involving Fourier transforms, because one can use the wave nature of light for those.

But general-purpose computing? More difficult.

What one's components are to do is a much easier problem, however, at least so it seems to me.

 List of open-source hardware projects - the open-source part is the hardware designs, not the hardware itself.  Open-source hardware noting  Open-design movement

Home :: OpenCores for instance, and  OpenRISC

 

[steve_bank]

Don't know how much is available outside a pay wall.

Optical Society of America - SPARC

In the mid-90s when leaders of Optical Society of America decided to launch an open-access publication, the term “Open Access” hadn’t yet been coined.

sparcopen.org

SPIE - the international society for optics and photonics

SPIE is a non-profit dedicated to advancing the scientific research and engineering applications of optics and photonics through international conferences, education programs and publications.

spie.org