Opto-Electronics to Take Care of Data Explosion

As we come nearer to an intelligent IoT world, one of the major concerns we talk every day is about data explosion, its storage, and access and so on. In the beginning of the year, I had blogged about some facts that indicated successful emergence of IoT in very near future. My faith gets further strengthened when I envision the semiconductor world going through another revolution with opto-electronic chips. In the near future, we can see Intel’s photonics technology on top of silicon that can enable high-speed, efficient and reliable data centers without power, heating or space problems in storing and handling Big Data.A LASER (Light Amplification through Simulated Emission of Radiation) is based on Raman Effect, invented by Sir C. V. Raman, an Indian physicist who received Nobel Prize for this discovery in 1930. LASER has been successful in glass fiber. In glass fiber, after travelling several kilometres, the laser beam acquires enough energy to cause a significant amplification of the data signal. Intel’s silicon photonicstechnology is actually a LASER in silicon. The Raman Effect is more than 10000 times stronger in silicon than in glass fiber. In silicon, the distance required is only in centimetres. Also, silicon is most cost effective and requires existing fabrication techniques. Since silicon cannot emit laser light, a waveguide (conduit for light in silicon) is etched into a silicon wafer.The silicon waveguide encountered another problem called ‘two-photon absorption’. In this, two photons arrive at an atom at the same time and the combined energy is enough to free an electron from an atom. At high power densities, the rate of creation of free electrons exceeds the rate of their re-combination with the crystal lattice. The free electrons then start absorbing the light passing through the silicon waveguide, thus diminishing the power of signals. To overcome this problem, the scientists at Intel Photonics Technology Lab inserted a diode-like PIN device in the wave guide that removed the free electrons to produce continuous amplification. Raman Effect was created to amplify the light as it bounced between two mirrors coated on the ends of the waveguide, thus producing a continuous laser beam at a new wavelength. This formed the breakthrough silicon laser. Look for more details in a whitepaper at Intel Photonics Lab website.Silicon laser alone was not enough, other components such as high-speed silicon modulators and silicon photo-detectors were developed. A chip can have multiple hybrid silicon lasers at different wavelengths and each modulated at say 50 Gbits/s. A silicon multiplexer can then combine all signals into a single optical fiber. At the other end of the fiber, another chip can have detectors to convert the optical signal from each laser back into electronic signal. At IDF 2013, Dr. Mario Paniccia, Director of Intel Photonics Technology Lab demonstrated a transceiver based on photonics technology, operating at 100 Gbits/s. Justin Rattner, CTO of Intel at that time, said that Intel has fully automated test technology for such photonic wafers that combines electrical, optical or RF test. It uses microscopic lenses to read optical signals.Fujitsuworked with Intel to demonstrate Optical PCI Express (OPCIe) server, which was enabled by Intel’s silicon photonics technology. It solves power and heat density problems which occur in Rack-based servers due to space and power constraints. Signals over optical fibers can go much longer compared to copper signals. Look for details about this prototype at Intel website here.Looking at these working devices, it’s certain that silicon chips will have another revolution to add optics into them. I am calling these as opto-electronic chips that can enable very high-speed, low latency connections and high storage in the cloud as demanded by the upcoming semiconductor market in the near future. I can envision this technology in main stream chip production sooner than later. Does it ask for another Nobel Prize for Intel scientists? In my view it could, provided it fulfils the larger need of high-speed computing, storage and access without too many issues as seen in copper wires. The cost must be affordable because silicon is always low cost compared to other materials for such use. Comments welcome!