Materials processing tricks enable engineers to create new laser material
by Staff Writers
San Diego CA (SPX) Jul 19, 2018
By doping alumina crystals with neodymium ions, engineers at the University of California San Diego have developed a new laser material that is capable of emitting ultra-short, high-power pulses - a combination that could potentially yield smaller, more powerful lasers with superior thermal shock resistance, broad tunability and high-duty cycles.
To achieve this advance, engineers devised new materials processing strategies to dissolve high concentrations of neodymium ions into alumina crystals. The result, a neodymium-alumina laser gain medium, is the first in the field of laser materials research. It has 24 times higher thermal shock resistance than one of the leading solid-state laser gain materials.
The research was published this month in the journal Light: Science and Applications. The team will also present their work at the 2018 SPIE Conference, Aug. 19 to 23 in San Diego.
Neodymium and alumina are two of the most widely used components in today's state-of-the-art solid-state laser materials. Neodymium ions, a type of light-emitting atoms, are used to make high-power lasers. Alumina crystals, a type of host material for light-emitting ions, can yield lasers with ultra-short pulses. Alumina crystals also have the advantage of high thermal shock resistance, meaning they can withstand rapid changes in temperature and high loads of heat.
However, combining neodymium and alumina to make a lasing medium is challenging. The problem is that they are incompatible in size. Alumina crystals typically host small ions like titanium or chromium. Neodymium ions are too big - they are normally hosted inside a crystal called yttrium aluminum garnet (YAG).
"Until now, it has been impossible to dope sufficient amounts of neodymium into an alumina matrix. We figured out a way to create a neodymium-alumina laser material that combines the best of both worlds: high power density, ultra-short pulses and superior thermal shock resistance," said Javier Garay, a mechanical engineering professor at the UC San Diego Jacobs School of Engineering.
Cramming more neodymium into alumina
"However, this process is too slow to work with neodymium ions as the dopant - they would essentially get kicked out of the alumina host as it crystallizes," explained first author Elias Penilla, a postdoctoral researcher in Garay's research group. So his solution was to speed up the heating and cooling steps fast enough to prevent neodymium ions from escaping.
The new process involves rapidly heating a pressurized mixture of alumina and neodymium powders at a rate of 300 C per minute until it reaches 1,260 C. This is hot enough to "dissolve" a high concentration of neodymium into the alumina lattice. The solid solution is held at that temperature for five minutes and then rapidly cooled, also at a rate of 300 C per minute.
Researchers characterized the atomic structure of the neodymium-alumina crystals using X-ray diffraction and electron microscopy. To demonstrate lasing capability, researchers optically pumped the crystals with infrared light (806 nm). The material emitted amplified light (gain) at a lower frequency infrared light at 1064 nm.
In tests, researchers also showed that neodymium-alumina has 24 times higher thermal shock resistance than one of the leading solid-state laser gain materials, neodymium-YAG. "This means we can pump this material with more energy before it cracks, which is why we can use it to make a more powerful laser," said Garay.
The team is working on building a laser with their new material. "That will take more engineering work. Our experiments show that the material will work as a laser and the fundamental physics is all there," said Garay.
Photonic capsules for injectable laser resonators
Seoul, South Korea (SPX) Jul 16, 2018
A KAIST research group presented photonic capsules for injectable laser resonators using microfluidic technology. The capsule's diameter is comparable to a human hair and stable in gas and liquid media, so it is injectable into any target volume. The research group headed by Professor Shin-Hyun Kim in the Department of Chemical and Biomolecular Engineering applied an interesting optical property from nature. Professor Kim, who has dived deep into photonic materials research inspired from nature su ... read more
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.