Group items tagged

Engineers at Stevens Institute of Technology have developed a technique to optically modulate the frequency of a laser beam and create a signal that is disrupted significantly less by environmental factors, says Dr. Rainer Martini. The research provides for enhanced optical communications, allowing mobile units not tied to fiber optic cable to communicate in the range of 100 GHz and beyond, the equivalent of 100 gigabytes of data per second. Eventually, the team hopes to extend the reach into the terahertz spectrum. The frequency or amplitude modulation of middle infrared quantum cascade lasers has been limited by electronics, which are barely capable of accepting frequencies of up to 10 GHz by switching a signal on and off.  Marini and his team have developed a method to optically induce fast amplitude modulation in a quantum cascade laser to control the laser's intensity. Their amplitude modulation system employed a second laser to modulate the amplitude of the middle infrared laser, using light to control light. The current detector is only capable of detecting frequencies up to 10 GHz, but Dr. Martini is confident that a new detector will make the system capable of much higher frequencies. With an optical system that is stable enough, satellites may one day convert to laser technology, resulting in a more mobile military and super-sensitive scanners, as well as faster Internet for the masses, says Martini. Ref.: "Optically induced fast wavelength modulation in a quantum cascade laser," Applied Physics Letters, July 7, 2010.

Graphene-based modulators could soon allow consumers to stream full-length, high-definition, 3-D movies onto a smartphone in a matter of seconds, the researchers said.

A simple technique for stamping patterns invisible to the human eye onto a special class of nanomaterials has been developed by researchers at Vanderbilt University. The new method works with porous nanomaterials that are riddled with tiny voids, which give them unique optical, electrical, chemical, and mechanical properties. There are nanoporous forms of gold, silicon, alumina, and titanium oxide, among others. The technique involves the creation of pre-mastered stamps using traditional, but complex, clean room processes and then using the stamps to create patterns using a new process called direct imprinting of porous substrates (DIPS). DIPS can create a device in less than a minute, regardless of its complexity. The smallest pattern the researchers have made to date has features of only a few tens of nanometers (about the size of a single fatty acid molecule). They have also succeeded in imprinting the smallest pattern yet reported in nanoporous gold, one with 70-nanometer features. The first device the group has created is a "diffraction-based" biosensor that can be configured to identify a variety of different organic molecules, including DNA, proteins and viruses. The researchers envision a wide range of applications including drug delivery, chemical and biological sensors, solar cells, and battery electrodes.

ScienceDaily (July 11, 2011) - Researchers at Columbia Engineering School have built optical nanostructures that enable them to engineer the index of refraction and fully control light dispersion.

Free Download - StanfordUniversity - January 22, 2009 - Karl Deisseroth is pioneering bold new treatments for depression and other psychiatric diseases. By sending pulses of light into the brain, Deisseroth can control neural activity with remarkable precision. In this short talk, Deisseroth gives an thoughtful and awe-inspiring overview of his Stanford University lab's groundbreaking research in "optogenetics".