New class of glass in sharp focus

Researchers claim to have developed a new family of glasses that will bring higher power to smaller packages in lasers and optical devices and provide a less-expensive alternative to many other optical glasses.

Researchers have developed a new family of glasses that will bring higher power to smaller packages in lasers and optical devices and provide a less-expensive alternative to many other optical glasses and crystals, like sapphire.

Called REAl Glass (Rare-earth – Aluminium oxide), the materials are said to be durable, provide a good host for atoms that improve laser performance, and may extend the range of wavelengths that a single laser can currently produce.

With support from the US National Science Foundation (NSF), Containerless Research, Inc (CRI), based in the Northwestern University Evanston Research Park in Illinois, recently developed the REAl Glass manufacturing process. NSF is now supporting the company to develop the glasses for applications in power lasers, surgical lasers, optical communications devices, infrared materials, and sensors that may detect explosives and toxins.

CRI originally developed the glasses with funding from NASA. The research used containerless processing techniques, including a specialised research facility -the Electrostatic Levitator – at the NASA Marshall Space Flight Center in Huntsville, Alabama. The levitator, a device that allows materials to float with no visible means of support or containment, is one of the USA’s few facilities where scientists can process materials without using contaminating containers.

REAl Glass, like many other glasses, is made from a supercooled liquid. This means that the liquid is cooled quickly enough to prevent its atoms from organising and forming a crystal structure. At lower temperatures, such as room temperature, the atoms are ‘fixed’ in this jumbled, glassy state. In REAl Glass, the glass making process also provides a mechanism for incorporating rare-earth elements in a uniform way. This quality makes REAl Glass particularly attractive for laser applications.

After CRI scientists spent several years on fundamental research into fragile liquids, NSF provided funds to develop both patented glasses and proprietary manufacturing processes for combining the glass components in commercial quantities and at a much lower cost than for levitation melting.

Using high temperature melting and forming operations, CRI is making REAl Glass in 10mm thick rods and plates, establishing a basis for inexpensive, large-scale production of sheet and rod products.

‘The REAl Glass products are a new family of optical materials,’ said Richard Weber, the CRI principal investigator on the project, who adds that CRI is already meeting with businesses to talk about requirements for laser, infrared window, and other optical applications and supplying finished products or licensing the material for use.

‘The REAl Glass technology combines properties of competing materials into one [material],’ says NSF’s Sargeant. ‘With these glasses researchers can design smaller laser devices, because of the high power density that can be achieved, and can provide small, high-bandwidth devices for applications in the emerging fibre-to-the-home (FTTH) telecom market.’

Because the glass can incorporate a variety of rare-earth elements into its structure, CRI can craft the glasses to yield specific properties, such as the ability to tune a laser across multiple light wavelengths. The ability to tune the light wavelength can have important implications for the lasers used in dental procedures and surgery, providing more control for operations involving skin shaping or cauterisation.

CRI is also continuing basic research on fragile oxide liquids, which they believe still offer much potential for generating new materials, and ultimately, optical devices.