Adrian Cho in Science:
The feeble force of light alone can flip a nanometer-sized mechanical switch one way or the other, a team of electrical engineers reports. The little gizmo holds its position without power and at room temperature, so it might someday make a memory bit for an optical computer. Other researchers say it also introduces a promising new twist into the hot field of “optomechanics,” which marries nanotechnology and optics. “This a new paradigm,” says Markus Aspelmeyer, a physicist at the University of Vienna who was not involved in the research. “People are going to take a good look at this and use it in other schemes.”
Since 2005, physicists and engineers have been using light to set tiny structures vibrating and control their motion. Much of their effort has focused on using light to suck energy out of a vibrating beam or cantilever to try to achieve new states of motion that can be described only by quantum mechanics, extending the quantum realm to the movement of humanmade objects. In fact, Aspelmeyer, Oskar Painter of the California Institute of Technology in Pasadena, and colleagues have managed to use laser light to “cool” a vibrating beam to the lowest energy state possible, the so-called quantum ground state, a key step toward achieving more complex quantum states of motion, as they reported 6 October in Nature.
Now, taking a different tack, Mahmood Bagheri, Hong Tang, and colleagues at Yale University have used laser light to pump energy into a tiny bridge of silicon, flipping it between two stable configurations—in effect, making a mechanical switch. The bridge measured 10 micrometers long, 500 nanometers wide, and 110 nanometers thick and was suspended about 250 nanometers above a glass chip. When researchers etched glass out from under it, the silicon expanded, so the bridge bowed either upward or downward, like a playing card squeezed lengthwise between your thumb and forefinger.
The trick was to use light to make the bridge shift between the two positions in a controllable way.