Featured Research

from universities, journals, and other organizations

'Dark Pulse Laser' produces bursts of ... almost nothing

Date:
June 11, 2010
Source:
National Institute of Standards and Technology (NIST)
Summary:
In an advance that sounds almost Zen, researchers have demonstrated a new type of pulsed laser that excels at not producing light.

Colorized trace of pulses from the NIST/JILA "dark pulse" laser, indicating the light output nearly shuts down about every 2.5 nanoseconds.
Credit: Talbott/NIST

In an advance that sounds almost Zen, 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 behavior.

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.

The new laser depends on the qdots' unusual energy dynamics, which have the effect of stabilizing dark pulses. After emitting light, qdots recover energy from within rapidly (in about 1 picosecond) but more slowly (in about 200 picoseconds) from energy inputs originating outside the qdots in the laser cavity. This creates a progression of overall energy gains gradually giving way to overall energy losses. Eventually, the laser reaches a steady state of repeated brief intensity dips -- a drop of about 70 percent -- from the continuous light background.

The dark pulse laser was developed through close collaborations between NIST experts in qdot growth and semiconductor laser design and fabrication, and JILA experts in ultrafast lasers and related measurements. NIST has ongoing research efforts to develop quantum dot lasers and to develop modeling, fabrication, and measurement methods for semiconductor nanostructures such as quantum dots. In general, semiconductor lasers are being considered for many advanced applications, such as next-generation atomic clocks based on optical frequencies, for which large lasers are costly and complex.


Story Source:

The above story is based on materials provided by National Institute of Standards and Technology (NIST). Note: Materials may be edited for content and length.


Journal Reference:

  1. Mingming Feng, Kevin L. Silverman, Richard P. Mirin, Steven T. Cundiff. Dark pulse quantum dot diode laser. Optics Express, 2010; 18 (13): 13385 DOI: 10.1364/OE.18.013385

Cite This Page:

National Institute of Standards and Technology (NIST). "'Dark Pulse Laser' produces bursts of ... almost nothing." ScienceDaily. ScienceDaily, 11 June 2010. <www.sciencedaily.com/releases/2010/06/100609171804.htm>.
National Institute of Standards and Technology (NIST). (2010, June 11). 'Dark Pulse Laser' produces bursts of ... almost nothing. ScienceDaily. Retrieved October 21, 2014 from www.sciencedaily.com/releases/2010/06/100609171804.htm
National Institute of Standards and Technology (NIST). "'Dark Pulse Laser' produces bursts of ... almost nothing." ScienceDaily. www.sciencedaily.com/releases/2010/06/100609171804.htm (accessed October 21, 2014).

Share This



More Matter & Energy News

Tuesday, October 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Thanks, Marty McFly! Hoverboards Could Be Coming In 2015

Thanks, Marty McFly! Hoverboards Could Be Coming In 2015

Newsy (Oct. 21, 2014) If you've ever watched "Back to the Future Part II" and wanted to get your hands on a hoverboard, well, you might soon be in luck. Video provided by Newsy
Powered by NewsLook.com
Robots to Fly Planes Where Humans Can't

Robots to Fly Planes Where Humans Can't

Reuters - Innovations Video Online (Oct. 21, 2014) Researchers in South Korea are developing a robotic pilot that could potentially replace humans in the cockpit. Unlike drones and autopilot programs which are configured for specific aircraft, the robots' humanoid design will allow it to fly any type of plane with no additional sensors. Ben Gruber reports. Video provided by Reuters
Powered by NewsLook.com
Graphene Paint Offers Rust-Free Future

Graphene Paint Offers Rust-Free Future

Reuters - Innovations Video Online (Oct. 21, 2014) British scientists have developed a prototype graphene paint that can make coatings which are resistant to liquids, gases, and chemicals. The team says the paint could have a variety of uses, from stopping ships rusting to keeping food fresher for longer. Jim Drury reports. Video provided by Reuters
Powered by NewsLook.com
Massive Air Bag Recall Affects More Than 4.5 Million Vehicles

Massive Air Bag Recall Affects More Than 4.5 Million Vehicles

Reuters - US Online Video (Oct. 21, 2014) Major automakers are recalling millions of vehicles due to potentially defective front passenger air bag inflators that can rupture and spray metal shrapnel. Linda So reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins