Light-powered micro-machines to advance telecommunications

November 2, 2007
Light-powered micro-machines to advance telecommunications
Rings, one millionth of a meter in size, are the moving parts of a 'smart' micromachine that could be powered and controlled by light on an optical chip. The rings move around and adapt to the color of light that is traveling through the bar, right. Image courtesy / Peter Rakich

A new theory developed at MIT could lead to "smart" optical microchips that adapt to different wavelengths of light, potentially advancing telecommunications, spectroscopy and remote sensing.

Drawn by the promise of superior system performance, researchers have been exploring the concept of microchips that manipulate light instead of electricity. In their new theory, the MIT team has shown how such chips could feature tiny machines with moving parts powered and controlled by the very light they manipulate, giving rise to fundamentally new functionality.

"There are thousands of complex functions we could make happen by tinkering with this idea," said Peter Rakich, an MIT postdoctoral associate who invented the theoretical concept along with postdoc Milos Popovic. The work was described in the cover story of the November issue of Nature Photonics.

For example, such chips could one day be used to remotely adjust the amount of bandwidth available in an optical network, or to automatically process signals flowing through fiber-optic networks, without using any electrical power, Rakich said.

Coauthors on the paper were Marin Soljacic, assistant professor of physics; and Erich Ippen, the Elihu Thomson Professor of Electrical Engineering and professor of physics.

"The idea that opto-nanomechanical devices can be designed to self-adapt to all-optical control-i.e., by self-aligning their resonances to optical control frequencies and by permitting all-optical tuning and dimension control-is new and exciting," said Ippen.

Earlier this year an MIT team composed of many of the same researchers showed that photonic circuitry could be integrated on a silicon chip by polarizing all of the light to the same orientation. The current work shows how tiny mobile machines can be built on such chips, taking advantage of the substantial pressures exerted by photons as they strike the walls of a cavity.

In the macroscopic world, light waves do not exert significant forces, but in the unique world of the microscopic, coupled with ultrapure laser light, photons bouncing off the walls of a cavity can build up a measurable force called radiation pressure. This is similar to the pressure exerted by gas molecules trapped in an aerosol can.

To take advantage of this radiation pressure, the researchers propose machines built from ring-shaped cavities only millionths of a meter in size located on the chip surface. When pressure on the cavity walls is high enough, the cavity is forced to move. This movement forms a critical part of an optical micromachine, which adjusts its configuration to respond to light in a predesigned way.

A unique application of this concept involves processing data that travels in fiber-optic networks. Today resonators employed in fiber-optic networks have to be synchronized with the incident light to ring at its frequency, in the same way an opera singer has to tune the pitch of her voice to make a wine glass ring.

Remarkably, a "smart" resonator based on the MIT concept could chase the frequency (color) of the laser light incident upon it. As the frequency of the laser beam changes, the frequency of the resonator will always follow it, no matter where it goes.

In other words, this new, unique resonator is like a wine glass that self-adjusts to the pitch of the singer's voice and follows it along throughout a song, Rakich said. He noted that physical systems that adapt to driving light and behave like these nanomachines do not exist elsewhere in nature.

By coupling the resonating cavities with nano-scale cantilevers, optical devices analogous to microelectromechanical systems (MEMS) devices can be created.

Although the researchers focused on ring-shaped cavities, their model could be applied to other structures as well.

"Our objective now is to develop a variety of light-powered micro- and nanomachines with unique capabilities enabled by this technology," explained Popovic. "But the first step will be to demonstrate the concept in practice."

Source: MIT

Explore further: Toward practical quantum computers: Built-in optics could enable chips that use trapped ions as quantum bits

Related Stories

Self-shading windows switch from clear to opaque

August 11, 2016

A team of researchers at MIT has developed a new way of making windows that can switch from transparent to opaque, potentially saving energy by blocking sunlight on hot days and thus reducing air-conditioning costs. While ...

Needles that hit the right mark

August 12, 2016

More than 13 million pain-blocking epidural procedures are performed every year in the United States. Although epidurals are generally regarded as safe, there are complications in up to 10 percent of cases, in which the needles ...

Quantum leap in quest for digital speed and security

July 28, 2016

Society's increasing reliance on the internet, computers and mobile phones puts stringent demands on technological developments. Shrinking the electronic components – in other words, increasing the number of transistors ...

Discovery could help treatments for sickle cell disease

August 8, 2016

An interdisciplinary, international group of researchers has found new biophysical markers that could help improve the understanding of treatments for sickle cell disease, a step toward developing better methods for treating ...

Study opens new realms of light-matter interaction

July 15, 2016

A new MIT study could open up new areas of technology based on types of light emission that had been thought to be "forbidden," or at least so unlikely as to be practically unattainable. The new approach, the researchers ...

Recommended for you

Quest to find the 'missing physics' at play in landslides

August 30, 2016

During the 1990s, Charles S. Campbell, now a professor in the Department of Aerospace and Mechanical Engineering at the University of Southern California, began exploring why large landslides flow great distances with apparently ...

Invisibility cloak with photonic crystals

August 30, 2016

Almost as elusive as unicorns, finding practical materials for invisibility cloaking is challenging. Michigan Technological University researchers have new ideas how to solve that.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.