Fibre networks swift as lightning
Data-hungry technologies such as video-on-demand services, real-time multiplayer gaming, cloud and server-side storage applications, and imminent virtual and augmented reality are fuelling demand for high data throughput and fast response times. To meet the ever-increasing growth of data traffic, data switching technologies require larger switching capacity and higher interconnect bandwidth. Researchers working on the EU-funded project SwIFT addressed this challenge with gusto. In an international first, they unveiled a novel switching mechanism in a photonic chip driven by tiny droplets that can potentially disrupt the future of data communications and telecoms. Combining photonics and microfluidics SwIFT relied on the rapidly growing silicon photonics technology that has recently proven to be an attractive platform for optical switches. In them, light is tightly confined in silicon waveguides due to its high refractive index. “This tight confinement allows the creation of very compact and high-density optical circuits. The high-yield wafer-scale processes that silicon photonics offer open up the possibility of creating sophisticated and reliable compact switch components that can be made at a relatively lower cost in high volume,” notes project coordinator Jan Watté. SwIFT has moved one step further, introducing a paradigm shift in the area of optical switches. At the core of the optical switch concept that the project introduced was to combine silicon photonics with fluidics. The light beam entering the switchboard in the silicon photonics chip can be switched from one waveguide to another depending on the position of droplets that are covering the waveguide structure in the chip. “The different refractive indexes of the two immiscible liquids we have used can significantly affect the propagation of the guided light in the underlying integrated optical component,” adds Watté. “Our approach allows us to engineer droplets that can rest in two states. When overcoming a certain threshold, the applied electric field allows the droplet to get above the mechanical barriers that keep it in a certain position and move to another microenvironment where it stays stable,” further explains Watté. The main advantage of the microfluidics approach is that in the absence of an electric field the droplet stays where it is and so the switch somehow remembers the configuration. This is exactly the concept behind a non-volatile optical switch. Non-volatile optical switches controlled by tiny droplets appeal to applications where continuous switching of multiple optical signals is equally important with the switching speed. Such components allow broadband operation with a switching speed in the order of milliseconds. This can prove very useful for managing the fibre infrastructure in access networks where typically several wavelength bands need to be switched simultaneously. SwIFT’s ambition was to stretch the limits of both photonics and fluidics technologies to demonstrate their effect on an optical switch with hundreds of ports. Faster, cheaper, smaller Optical switches that are typically implemented in fibre networks are bulky and expensive. However, the newly introduced fibre optic switching technology can reduce energy costs across telecommunications and automate manual processes, allowing operators to use software to patch and re-patch cables. “As far as we know, this is the first time that a non-volatile optical switch has been implemented by combining silicon photonics and microfluidics,” notes Watté. This compact, low-cost, multi-port optical telecommunication switch for remote fibre management should greatly boost optical fibre data speeds.
Keywords
SwIFT, optical switch, fluidics, droplet, silicon photonics, non-volatile, telecommunication, compact, fibre network
