The Final Stage of the Optical Revolution: Photonic Computers

 The photonic revolution began with optical fibre, but it will end with optical computers. The German company Q.ANT has designed and is manufacturing itself one of the first all-optical commercial line of computers. Photonic computers are really analogue calculators. The advantage over electron-based digital computers is not the speed of light versus electrons. Their velocities are similar. Instead, the real difference is that digital computers flip zeros and ones using transistors in combination with capacitors. Capacitors must charge and discharge. This takes a lot of time. It also consumes a lot of power all of which ends up as heat. 😃Even a simple addition of two numbers requires approximately 200 transistors. Taking the square root of a number involves 7000 transistors and the work horse Fourier transformation requires roughly 1 million transistors. Note that glasses also passively perform a Fourier transformation. In other words a single optical device in a computer can do a Fourier transformation without the million transistors. Most components comprising a photonic computer are passive optical components that transform the light as it passes through them. Faster, simpler, and consumes roughly 3% of the electricity that a digital computer requires to do the same tasks. 

The big challenge that must be overcome to create commercial successful optical computers is light loss or attenuation. Any light loss causes numerical errors. This Germany company's success largely reflects its ability to reduce optical attenuation using exotic materials like lithium. It has achieved 8 digit numerical accuracy.