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:
Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.
This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...