Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New in depth study to understand and control the optical damage caused by lasers on

03.07.2008
A new study undertaken by the non lineal optics and wave guides research group belonging to the department of Material Science of the UAM has advanced current understanding as well as the control of optical damage in crystals, offering new ways to increase light-power output of future optical integrated circuits.

Many of the lasers used today, both in scientific or technological applications have such a high light output power that the light itself damages or even destroys the crystals used to control, guide or manipulate it inside photonic devices (devices that only work with light).

Even at not so high powers, distortion effects take place in crystalline materials that change the characteristics of the laser beam as it propagates through the material. This effect is called optical damage and is mainly caused by the photorefractive phenomenon, which is caused by the presence of defects or atomic impurities, the electrons of which are excited by the light and scatter within the material. This movement of electrons creates internal electrical fields that alter the refractive index of electrotropic crystals, hence affecting the propagation of the light through them.

In many cases, the photorefractive effect is useful. It grants control over the propagation of light in a crystal by means of other light beams and also allows the storage of information as holograms. Nevertheless, at high light intensities, the photorefractive effect strongly degrades the light beam (fig. 1), a fact which currently introduces great difficulties for the arrival of new photonic integrated devices such as micro lasers, electro optical modulators, or frequency transducers that require higher efficiencies at higher intensities.

For many years, researchers from the non lineal optics and wave guides group of the department of Material Science of the UAM have studied the response of one of the most used crystals in the history of photonics, lithium niobate, to intense laser light. Their knowledge has made possible the development of a model that explains the optical damage through photorefractive effects in this crystal but it can also be applied to other electro-optic crystals. The most relevant idea of this model is based on new discoveries relating to the atomic defects of crystals that influence the photo refraction at high light intensities as well as the capacity to amplify optical noise.

With this model the minimum light intensity (Sensory threshold) at which the damage appears, as a function of defect concentration, temperature and other crystal properties can be predicted. The study also offers scientists and physicists a guide to optimize the properties of the crystal and the design of devices, enabling a rise of the laser light intensity in the crystal to 106 W/cm2, which represents an increase of the damage intensity threshold of a normal crystal by a factor of 10,000.

This study was carried out by the researchers Mercedes Carrascosa, Angel García Cabañes, José Manuel Cabrera and the doctorate students Javier Villarroel y Jesús Carnicero from the department of Material Science of the UAM has been published in the prestigious magazine of the American optics society, “Optics Express” in January 2008 (vol. 16, pages 115-120).

Oficina Información Científica | alfa
Further information:
http://www.uam.es
http://dx.doi.org/10.1364/OE.16.000115

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New proton record: Researchers measure magnetic moment with greatest possible precision

High-precision measurement of the g-factor eleven times more precise than before / Results indicate a strong similarity between protons and antiprotons

The magnetic moment of an individual proton is inconceivably small, but can still be quantified. The basis for undertaking this measurement was laid over ten...

Im Focus: Frictional Heat Powers Hydrothermal Activity on Enceladus

Computer simulation shows how the icy moon heats water in a porous rock core

Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

IceCube experiment finds Earth can block high-energy particles from nuclear reactions

24.11.2017 | Physics and Astronomy

A 'half-hearted' solution to one-sided heart failure

24.11.2017 | Health and Medicine

Heidelberg Researchers Study Unique Underwater Stalactites

24.11.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>