all lasers stories

Laser precision added to search for new Earths

404132862 — Wed, 02 Apr 2008 14:46:48 -0400

Harvard scientists have unveiled a new laser-measuring device that they say will provide a critical advance in the resolution of current planet-finding techniques, making the discovery of Earth-sized planets possible.

The discovery of planets outside of our solar system, called “exoplanets,” is one of the hottest fields in astronomy and holds great promise to increase our understanding of Earth’s solar system and of how life first took hold on this planet.

Compact, wavelength-on-demand Quantum Cascade Laser chip created

404132862 — Tue, 05 Feb 2008 16:10:50 -0500

Engineers at Harvard's School of Engineering and Applied Sciences have demonstrated a highly versatile, compact and portable Quantum Cascade Laser sensor for the fast detection of a large number of chemicals, ranging from infinitesimal traces of gases to liquids, by broad tuning of the emission wavelength. The potential range of applications is huge, including homeland security, medical diagnostics such as breadth analysis, pollution monitoring, and environmental sensing of the greenhouse gases responsible for global warming.

Body art for the faint of heart

70652986 — Mon, 26 Mar 2007 05:46:35 -0400

Ever wish you could get rid of that tattoo of barbed wire around your wrist, or the forearm-length dragon you once thought of as so stylish or macho?

It's not easy. You can go through a long, expensive series of laser treatments, and still not get it completely erased. You can have it sanded off, literally, but that could leave a scar.

Harvard scientists develop 'plug and play' laser

50443248 — Wed, 25 Jul 2007 12:46:53 -0400

Engineers and applied physicists have demonstrated the feasibility of a new type of plug-in laser that could lay the groundwork for wide-ranging security applications.
Their Raman injection laser, described in the most recent issue of the journal Nature, combines the advantages of nonlinear optical devices and semiconductor injection lasers with a compact "plug and play" design.

"While our paper merely demonstrates proof of concept, one day it may lead to the sort of security experts dream of having: a portable device that you could use to detect things like weapons or explosives simply by shining an invisible light to see what someone might be hiding," says Federico Capasso, Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering in Harvard University's Division of Engineering and Applied Sciences. "The work also represents an important advance in quantum design since we are now able to engineer, from the bottom-up, a new Raman material and laser, and tailor its property for a given application."

While Raman lasers have been used for a long time, they have generally required a large and powerful pump to compensate for the beam's weakening as it propagates through a material. In their work, Capasso and his colleagues were able to combine the pump and the material itself in a single device.

Conventional Raman lasers depend on a fundamental phenomenon in physics called the Raman effect: the change in the frequency of monochromatic light, such as that found in a laser, when it passes through a substance. When light from an intense laser beam, known as the "pump," deflects off the molecules of certain materials, some of the incident photons lose part of their energy. As a result, a secondary laser beam, with a frequency shifted from that of the first, emerges from the material.

By combining the power source and the Raman material together, literally creating a laser-within-a-laser, the team has created the first current-driven Raman laser. The current generates an internal laser beam within a material, which, in turn, generates the Raman laser radiation. Because the pump laser is now self-generated, the device is highly efficient, reducing the standard decline that happens when an external power source is used.

Lasers produce slow, cold antiatoms

50443248 — Wed, 25 Jul 2007 15:17:10 -0400

A new way to make colder atoms of antimatter has been found. It could help bring scientists closer to understanding why we, and everything else, are made out of matter instead of antimatter.
According to the best theories, ordinary matter and its shadowy twin were created in approximately equal amounts when the universe came into existence some 14 billion years ago. If that's true, then where has all the antimatter gone?

"The imbalance is an embarrassing thing in physics, something we don't talk about," admits Gerald Gabrielse, Leverett Professor of Physics at Harvard University. To solve this universal mystery, researchers want to get a good look at antimatter atoms. To get such a view, they need a good way to slow them down.

New use found for black silicon

70652986 — Mon, 26 Mar 2007 05:15:59 -0400

In 1999, Harvard researchers used laser pulses to etch the surface of silicon, the most common substance used in electronic devices. By accident, they created a material that efficiently traps light. Called black silicon, it holds amazing potential for efficiently converting sunlight to electricity, for communicating by light, and for monitoring the environment for evidence of pollution and global warming. Now, a Harvard graduate student has discovered another use for black silicon. When placed in a strong electric field, the substance emits electrons with surprising efficiency.

New treatment effective against psoriasis

70652986 — Mon, 26 Mar 2007 05:07:50 -0400

Psoriasis is a skin disease that disfigures people's bodies with scaly red plaques. Thirteen patients had portions of their psoriasis patches irradiated with intense beams of ultraviolet laser light at Massachusetts General Hospital. Other parts of the plaques were left untreated for comparison. After only five treatments, one patient's redness, scales, and discomfort disappeared from the irradiated areas. Other patients required only a single treatment, lasting a few minutes, to clear their skin. In all cases, the treated areas remained clear for more than six months. Researcher Charles Taylor feels sure ultraviolet lasers will be adapted to treat other common skin maladies that distress millions of people in the United States. These include eczema, chronic itching, sun poisoning, vitiligo, and purple, lichen-looking markings known as lichen planus. Vitiligo produces a loss of pigment, resulting in splotches of light skin on dark-skinned individuals.

Black silicon: A new way to trap light

70652986 — Mon, 26 Mar 2007 05:04:34 -0400

Eric Mazur, Harvard College Professor and Gordon McKay Professor of Applied Physics, and his students were studying what kinds of new chemistry can occur when lasers shine on metals, like platinum. One day, they decided to put a chip of gray silicon into a vacuum chamber, add some halogen gas, and scan it with ultrashort, ultra-intense laser pulses. Each pulse lasted a mere 100 millionths of a billionth of a second. However, the energy in a single pulse approximates focusing all the sunlight hitting Earth at one time onto a space the size of a fingernail. After more than 500 pulses, the silicon turned black. It wasn't burned; rather, its surface had been etched by the heat and gas into a dazzling forest of billions of minute needlelike spikes.