Nanoparticle Scattering Improves Laser Performance

Jun 04, 2009

(PhysOrg.com) -- “Light scattering” and “optical performance” are two concepts that usually head in opposite directions, but they have recently been shown to walk happily hand-in-hand. The results are impressive laser output from some new composite materials and the potential for making commercially viable solid-state dye lasers.

In an article in , Dr. Inmaculada Garcia-Moreno and her colleagues at the Instituto de Quimica-Fisica “Rocasolano” and the Instituto de Ciencia y Tecnología de Polímeros in Madrid have shown that certain nanoparticles added to dye lasers can scatter light in a way that increases the efficiency of the material’s action as well as make the materials easier to handle.

Lasers made from dyes can be tuned over a very broad visible wavelength, from the near ultraviolet to the infrared. They can be pulsed at high energy and are used for applications ranging from isotope separation and pollution monitoring to cancer therapies and tattoo removal. As the dyes used are liquids it is often helpful if they can be incorporated into a solid material. Organic polymer materials are usually used for this purpose, and inorganic particles are often added to improve the physical stability and handling properties. Unfortunately, the inorganic additives usually have detrimental effects on the optical properties of the composites, such as transparency and laser capabilities.

However, as the Spanish researchers have demonstrated, if the inorganic material comprises particles that are both small enough and randomly enough distributed, then the transparency of the composites is not affected and the emission from the dye is actually enhanced.

The chemistry that has made this possible is the use of nanoparticles of polyhedral oligomeric silsesquioxane (POSS) for the inorganic component. POSS is a silicon and oxygen-based material that can be readily incorporated into an organic matrix. The nanoparticles were found to be dispersed on a molecular level. The physics behind the laser enhancement is a phenomenon known as “incoherent random laser”, in which the coherent light emitted by the dye is scattered weakly by the POSS nanoparticles, causing it to have an elongated path inside the material and providing extra feedback.

The researchers initially found it difficult to realize that a homogeneous material with nanoparticles in the range 0.5-4 nm could sustain scattering, but were able to show that not only did it occur, but that the effect was independent of the type of dye molecules used and their photophysics. “Thus,” Dr. Garcia-Moreno claims, “dye-doped POSS solutions could be defined as a kind of universal gain media, overcoming the dye/host specificity that has been recognized as one of the greatest limitations of these laser systems.”

Other advantages include “the easy synthesis of the POSS-based hybrid materials” and “their significantly improved physical, thermal, and optical properties as compared with the materials used up to now for incorporating lasing dyes”. The researchers therefore see the possibility of using these new hybrid materials as alternative sources for optoelectronic devices, competing with dendronized or grafted polymers. “The POSS-based materials show the potential to bring to life a practical, commercial, easy-to-handle, and stable solid-state dye laser.”

More information: Dye-Doped POSS Solutions: Random Nanomaterials for Laser Emission; A. Costela, I. Garcia-Moreno, L. Cerdan, V. Martin, O. Garcia, and R. Sastre, Advanced Materials, 2009, DOI: 10.1002/adma.200900799; doi.wiley.com/10.1002/adma.200900799

Provided by Wiley (news : web)

Explore further: Microfluidics and nanofluidics research provide inexpensive ways to analyze blood and filter water (w/ Video)

add to favorites email to friend print save as pdf

Related Stories

Can silver nanoparticles be the key to a more compact laser?

Jun 09, 2008

“In random media, multiple scattering and interference reduce the diffusion of light, and in case of extremely strong scattering, photon localization, or Anderson localization of light, is predicted like electrons in glasses,” ...

Scientists succeed in cooling solid material with laser

Jul 26, 2006

A team of researchers at the University of the Basque Country have experimentally demonstrated something that other scientists have been trying to achieve for decades: the cooling of erbium-doped materials with laser light.

The Dye with the Pumpkin Cuff

Jun 20, 2005

Complexation with a large cuff-shaped molecule stabilizes rhodamine dye fluorescence When irradiated, fluorescent dyes emit light at a different wavelength; for scientists and engineers, these dyes are extremely important aide ...

Light-Emitting Diodes for Night-Vision Displays

Jan 23, 2007

More and more, conventional inorganic semiconductor electronics are being complemented with organic components. For example, flexible displays, large illuminated displays, or flat-panel displays can be made from organic light-emitting ...

A Good Eye for Oxygen

Mar 27, 2009

(PhysOrg.com) -- We cannot live without it; yet too much of it causes damage: oxygen is a critical component of many physiological and pathological processes in living cells. Oxygen deficiency in tissues is thus related to ...

Recommended for you

User comments : 0