»MIT works toward 'smart' optical microchips
~ microchips 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
~ such chips could feature tiny machines with moving parts powered and
~ controlled by the very light they manipulate, giving rise to fundamentally new functionality
~ 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
~ 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
~ shown that photonic circuitry can 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,
~ 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
~ 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
~ 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
~ 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
~ objective is to develop a variety of light-powered micro- and nanomachines with unique capabilities enabled by this technology
~ the first step will be to demonstrate the concept in practice
~ the research was funded in part by the Army Research Office through MIT's Institute for Soldier Nanotechnologies