Towards Stable Propagation of Light in Nanophotonic Fibers
September 19, 2016 | Institute for Basic ScienceEstimated reading time: 3 minutes
Devices based on light, rather than electrons, could revolutionize the speed and security of our future computers. However, one of the major challenges in today's physics is the design of photonic devices, able to transport and switch light through circuits in a stable way. Sergej Flach, Director of the Center for Theoretical Physics of Complex Systems, within the Institute for Basic Science (IBS) and colleagues from the National Technical University of Athens and the University of Patras (Greece) have studied how to achieve a more stable propagation of light for future optical technologies. Their model was recently published in Scientific Reports.
No matter from which fiber the light is launched (core 1 in the graph on the left, or core 2 in the left of the right), the result is a stable wavelight.
Optical fibers can carry a large amount of information and are already used in many countries for communications via phone, internet and TV. However, when light travels long distances through these fibers, it suffers from losses and leakages, which could lead to a loss of information. In order to compensate for this problem, amplifiers are positioned at specific intervals to amplify the signal. For example, amplifiers are needed in submarine communications cables that allow the transfer of digital data between all continents (except for Antarctica). Researchers have tried to build fibers where the signal is stable along the pathway and does not need amplifiers, using the so-called “PT symmetry”. P stands for parity reversal and T for time reversal.
Simplification to represent Parity-Time symmetry
Simplification to represent PT (Parity-Time) symmetry. Imagine a situation where two cars are traveling at the same speed at some instant in time, but car A is speeding up, and car B is slowing down. In order to go at the same speed, you can jump from one car to the other (Parity reversal) and back in time (Time reversal). The cars are like the light waves inside the fiber, the speed of the cars is a representation of the intensity of light and the jump symbolizes a phenomenon called tunneling.
The PT symmetry can be simplified with an example. Imagine a situation where two cars are traveling at the same speed at some instant in time. However, one car is speeding up and the other one is slowing down. Using parity reversal (P) we exchange one car for the other. Using time reversal (T) we go back in time. If you are in the car that is accelerating, you can jump to the car that is slowing down (P) and you also go back in time (T). As a result, you will end up with the same speed as the accelerating car. The cars are like light waves inside the optical fibers and the speed is a representation of the intensity of light. The jumping symbolizes of the transfer of light from one fiber to another, which happens when the light waves propagating in each fiber overlap partially with each other, through a phenomenon called tunneling.
The PT symmetry idea is that one can carefully balance the intensity of light inside the fibers and achieve a stable propagation. Researchers expected PT symmetry to be the solution to achieve stable propagation in all-optical devices (diodes, transistors, switches etc.). However, stable propagation is still a challenge because the PT symmetry conditions have to be balanced extremely carefully, and because the material of the fibers reacts and destroys the exact balance. In the example of the cars, in order to achieve perfect PT symmetry, you would need really identical cars and street conditions. Reality is of course much different.
The team led by IBS found that the stability of light propagation can be achieved by breaking the PT symmetry in a controlled way. In the example of the cars, you would have to choose two cars that are actually different (for example, one has a better engine than the other), but you choose the differences deliberately.
“You have the potential to realize a lot of the items of the wish-list of the PT symmetry, by breaking the PT symmetry. But you have to break it in the right way,” explains Professor Flach. “Now we know how to tune the characteristics of the fiber couplers to achieve a long-lasting constant light propagation.”
Suggested Items
Real Time with… IPC APEX EXPO 2024: Ventec Discusses New Pro-bond Family of Advanced Products
05/01/2024 | Real Time with...IPC APEX EXPOChris Hanson, Ventec's Global Head of IMS Technology, outlines the launch of four pro-bond formulas that deliver an outstanding combination of low dissipation factor (Df) with a dielectric constant (Dk) range to maximize the design window for critical PCB parameters. As Chris points out, Pro-bond is designed for low-loss, high-speed applications, while thermal-bond dissipates heat from a component through the board to a heat sink.
Siemens’ Breakthrough Veloce CS Transforms Emulation and Prototyping with Three Novel Products
04/24/2024 | Siemens Digital Industries SoftwareSiemens Digital Industries Software launched the Veloce™ CS hardware-assisted verification and validation system. In a first for the EDA (Electronic Design Automation) industry, Veloce CS incorporates hardware emulation, enterprise prototyping and software prototyping and is built on two highly advanced integrated circuits (ICs) – Siemens’ new, purpose-built Crystal accelerator chip for emulation and the AMD Versal™ Premium VP1902 FPGA adaptive SoC (System-on-a-chip) for enterprise and software prototyping.
Real Time with... IPC APEX EXPO 2024: Advancements in Laser Depaneling with LPKF
04/24/2024 | Real Time with...IPC APEX EXPOJake Benz, LPKF sales manager for North America, discusses the company's advancements in laser depaneling. LPKF has introduced a green wavelength laser for processing rigid FR-4 circuit boards, bringing significant gains in processing speeds to market. The company transitioned from IR CO2 to UV wavelength due to heat and burning issues.
Real Time with... IPC APEX EXPO 2024: Exploring IPC's PCB Design Courses with Kris Moyer
04/18/2024 | Real Time with...IPC APEX EXPOGuest Editor Kelly Dack and IPC instructor Kris Moyer discuss IPC's PCB design training and education offerings. They delve into course topics such as design fundamentals, mil/aero, rigid-flex, RF design, and advanced design concepts. They also highlight material selection for high-speed design, thermal management, and dissipation techniques. The interview wraps up with details about how to access these courses online.
Atg Luther Maelzer to Showcase Latest Generation Automatic Flying Probe Test System at IPC APEX EXPO 2024
04/01/2024 | atg Luther & Maelzeratg Luther Maelzer (a Mycronic company) will showcase their latest technology, the A9 with Automation (A9aL), at the upcoming IPC APEX EXPO. The A9AL will be on display from April 9th through the 11th on the show floor at the Anaheim Convention Center in Booth 4829.