Photonics: Better connected
A novel link between optical fibers and nanometer-scale silicon structures could aid the development of integrated optical circuits
Silicon is a unique material that has revolutionized electronics; it enables engineers to put millions of electrical devices onto a single chip. Replacing the electrical currents in this technology with beams of light could enable even faster information processing. Qian Wang at the A*STAR Data Storage Institute and co-workers1 have now designed a crucial component for such optical chips — a connector that links the silicon chip to an optical fiber. Such a device should enable efficient light input and output.
Silicon is a promising platform for dense photonic integration because sub-micrometer-sized silicon wires, known as waveguides, are capable of tightly confining and guiding light. As the technology required for processing silicon in this way already exists, silicon nanowires are attracting attention from the electronics industry. The challenge, however, is to be able to insert and extract a beam of light efficiently into and out of such tiny structures.
Wang and his team have now designed an ultra-compact lens that can be directly integrated into the silicon chip at the end of the waveguide. Their proposed lens is based on an idea known as a graded refractive index (GRIN) lens. The common GRIN lens usually distorts a light beam as it is collimated or focused, resulting in a so-called aberration. “We now propose a computational algorithm that can generate a novel graded refractive index profile for the GRIN lens and thus achieve aberration-free sub-wavelength focusing and highly efficient coupling,” says Wang.
The team of researchers’ graded index structure consists of a stack of alternating layers of two materials — for example, using silicon, which has a high refractive index, and silicon dioxide, which has a low refractive index. The layers of silicon are thicker than those of silicon dioxide at the optical axis, but this gradually reverses higher up in the stack.
Simulations showed how this structure could expand out light travelling along a 300 nanometer-thick silicon waveguide so that it couples to a fiber with a diameter of 10.4 micrometers. With appropriate anti-reflection coating, the coupling efficiency was calculated to be as high as 90%. The team of researchers also assessed the sensitivity of the optical coupling to any movement of the fiber, indicating that the new approach would provide a compact, efficient and robust way of achieving fiber-to-nanophotonic chip coupling. The next step will be to demonstrate this concept experimentally. “We plan to incorporate the idea into an electronic–photonic integration platform,” says Wang.
The A*STAR-affiliated researchers contributing to this research are from the Data Storage Institute
Lee Swee Heng | Research asia research news
The most recent press releases about innovation >>>
Die letzten 5 Focus-News des innovations-reports im Überblick:
Max Planck researchers revel the nano-structure of molecular trains and the reason for smooth transport in cellular antennas.
Moving around, sensing the extracellular environment, and signaling to other cells are important for a cell to function properly. Responsible for those tasks...
Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.
Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
What does it look like below the ice shelf of the calved massive iceberg A68?
On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.