Intel has formally reported a scientific breakthrough using a standard silicon manufacturing process to create the world’s first continuous wave silicon laser.
As reported in a recent issue of the journal Nature, Intel researchers have found a way to use the so-called Raman effect and silicon’s crystalline structure to amplify light as it passes through it. When infused with light from an external source, the experimental chip produces a continuous, high-quality laser beam. While still far from becoming a commercial product, the ability to build a laser from standard silicon could lead to inexpensive optical devices that move data inside and between computers at the speed of light.
According to the company, PCs of the future may come with a supply for powering tiny lasers, amplifiers and optical interconnects “that move terabytes of data around the computer and across networks”.
Today, these lasers cost tens of thousands of dollars each, limiting their use, but a chip-based laser built using standard manufacturing processes will be relatively inexpensive.
“Fundamentally, we have demonstrated for the first time that standard silicon can be used to build devices that amplify light,” says Dr. Mario Paniccia, director, Intel’s Photonics Technology Lab.
“The use of high-quality photonic devices has been limited because they are expensive to manufacture, assemble and package. This research is a major step toward bringing the benefits of low-cost, high-bandwidth silicon based optical devices to the mass market.”
The company explains that as light is pumped in to the silicon, the natural atomic vibrations amplify the light as it passes through the chip.
This amplification—the Raman effect—is more than 10,000 times stronger in silicon than in glass fibres. Raman lasers and amplifiers are used today in the telecom industry but rely on miles of fibre to amplify light. By using silicon, Intel researchers were able to achieve gain and lasing in a chip just a few centimetres in size.
Initially, Intel’s researchers discovered increasing the light pump power beyond a certain point no longer increased amplification and eventually even decreased it. The reason was a physical process called “Two-Photon Absorption”, which occurs when two photons from the pump beam hit an atom at the same time and knock an electron away. These excess electrons build up over time and collect in the waveguide until they absorb so much light that amplification stops.
The company’s solution was to integrate a P-type - Intrinsic - N (PIN)-type device into the waveguide. When a voltage is applied to the PIN, it acts like a vacuum and removes most of the excess electrons from the light’s path. The PIN device combined with the Raman effect produces a continuous laser beam.