* Astronomy

Members Login

Post Info

TOPIC: Quantum lasers

Blobrana

L

Posts: 131433

Date: Feb 17 19:29 2011

Anti-laser	Permalink

Scientists Build World's First Anti-laser More than 50 years after the invention of the laser, scientists at Yale University have built the world's first anti-laser, in which incoming beams of light interfere with one another in such a way as to perfectly cancel each other out. The discovery could pave the way for a number of novel technologies with applications in everything from optical computing to radiology. Read more __________________

Blobrana

L

Posts: 131433

Date: Jun 9 20:42 2010

Dark Pulse Laser	Permalink

Title: Dark pulse quantum dot diode laser Authors: Mingming Feng, Kevin L. Silverman, Richard P. Mirin, and Steven T. Cundiff Researchers at the National Institute of Standards and Technology (NIST) and JILA, a joint institute of NIST and the University of Colorado at Boulder, have demonstrated a new type of pulsed laser that excels at not producing light. The new device generates sustained streams of "dark pulses" - repeated dips in light intensity - which is the opposite of the bright bursts in a typical pulsed laser. Despite its ominous name, the dark pulse laser is envisioned as a tool for benign communications and measurements based on infrared light frequencies. The laser's ultrashort pulses span just 90 picoseconds (trillionths of a second), making the device suitable for measurements on short timescales. Dark pulses might be useful in signal processing because, unlike bright pulses, they generally propagate without distortion. Dark pulses might be used like a camera shutter for a continuous light beam in optical networks. Described in Optics Express, the new NIST/JILA technology is the first to generate dark pulses directly from a semiconductor laser cavity, without electrical or optical shaping of pulses after they are produced. The chip-sized infrared laser generates light from millions of quantum dots (qdots), nanostructured semiconductor materials grown at NIST. Quantum dot lasers are known for unusual behaviour. In the new NIST/JILA laser, small electrical currents are injected into the laser, causing the qdots to emit light. The qdots are all about the same size - about 10 nanometers (billionths of a meter) wide - and thus, because of a nanostructured design that makes them behave like individual atoms, all emit light at the same frequency. The current generates enough energy to amplify the emissions from the collective dots, creating the special properties of laser light. Read more IMAGE __________________

Blobrana

L

Posts: 131433

Date: Mar 28 18:01 2010

Quantum lasers	Permalink

Title: Quantum to classical transition in a single-ion laser Authors: François Dubin, Carlos Russo, Helena G. Barros, Andreas Stute, Christoph Becher, Piet O. Schmidt & Rainer Blatt The onset of lasing in a 'classical' laser is marked by a threshold that can be characterised by a sharp increase in photon flux as a function of external pumping strength. The same is not necessarily true for a single trapped atom interacting with a single optical mode. 'Quantum' lasers have shown thresholdless lasing in the regime of strong coupling between an atom and a radiation field, but the existence of a threshold has been predicted. Here, we demonstrate and characterise a single-atom laser with and without threshold behaviour by changing the strength of atom/light-field coupling. We observe the establishment of a laser threshold through the accumulation of photons in the optical mode even for a mean photon number substantially lower than for the classical case. Our observations mark an important step towards a fundamental understanding of laser operation in the few-atom limit including systems based on semiconductor quantum dots or molecules. Read more __________________

Page 1 of 1 sorted by

Create your own FREE Forum
Report Abuse