If you apply the right engineering principles, you can shake a transparent material in just the right way to enhance these effects and solve this major scientific challenge. Our field of research has found that light and sound do, in fact, interact in a very subtle way. "Light can pass through a transparent pane of glass without doing anything strange. "In everyday life, we don't see the interactions of light with sound," Bahl said. "Light-based communication is desirable because it produces much less heat, meaning that much less energy can be spent on server cooling while transmitting a lot more data per second."Īside from the technological potential, the researchers can't help but be mesmerized by the fundamental science behind this advancement. "Data centers handle enormous amounts of internet data traffic and consume large amounts of power for networking and for keeping the servers cool," Bahl said. Once perfected, they envision transformative applications in photonic communication systems, gyroscopes, GPS systems, atomic timekeeping and data centers. The researchers are looking for ways to increase bandwidth or data capacity of these isolators and are confident that they can overcome this hurdle. This is the first time that a magnetless isolator has surpassed gigahertz bandwidth," Sohn said. It is these sound waves that compel light within the device to travel only in one direction. "Sound waves are produced in a way similar to a piezoelectric speaker, using tiny electrodes written directly onto the aluminum nitride with an electron beam. The new device is only 200 by 100 microns in size - about 10,000 times smaller than a centimeter squared - and made of aluminum nitride, a transparent material that transmits light and is compatible with photonics foundries.
Until now, there has been no magnetless approach that is competitive." "The photonics industry cannot afford this material-related loss and also needs a solution that provides enough bandwidth to be comparable to the traditional magnetic technique. "Laboratory attempts at producing compact magnetic optical isolators have always been plagued by large optical loss," said graduate student and lead author Benjamin Sohn. However, the physical size of the device and the availability of materials are not the only problems with the current state of the art, the researchers said. In a study published in the journal Nature Photonics, the researchers explain how they use the minuscule coupling between light and sound to provide a unique solution that enables nonreciprocal devices with nearly any photonic material.
That is why industry desperately needs a better approach that uses only conventional materials and avoids magnetic fields altogether." But more importantly, the necessary materials are not yet available in photonics foundries. "First, industry simply does not have good capability to place compact magnets on a chip.
"There are several problems with using magnetically responsive materials to achieve the one-way flow of light in a photonic chip," said mechanical science and engineering professor and co-author of the study Gaurav Bahl. Today, the dominant technology for producing such nonreciprocal devices requires materials that change their optical properties in response to magnetic fields, the researchers said. They protect laser sources from back reflections and are necessary for routing light signals around optical networks.
Isolators are nonreciprocal or "one-way" devices similar to electronic diodes.