Hydrogen “Cure” for Optical Fiber Leads to High-Power Ultraviolet Laser Light
14 August 2014
Researchers at the National Institute of Standards and Technology (NIST) have found a way to use hydrogen to make optical fibers that transmit stable, high-power ultraviolet laser light for hundreds of hours. The hydrogen-treated fibers, which are detailed in Optics Express, are expected to reduce errors in logic operations in quantum computing experiments.
The research has shown that hydrogen molecules can heal the damage that occurs when short wavelength light interacts with dopants or impurities in optical fibers causing so-called "solarization" damage and severe losses of beam intensity. Because of this, the fibers are generally unable to transmit ultraviolet light, effectively shutting down.
But following the NIST researchers' tests of two types of fibers, the damage was 'cured' by exposure to ultraviolet laser light for several days. The fibres had solid cores made of fused silica and surrounded by lattices of air holes. These formed a crystal structure that maintained the shape of transmitted laser beams. The scientists infused the fibers with hydrogen gas at 100 times standard atmospheric pressure for between four and six days - some were treated in NIST's hydrogen pipeline materials testing facility.
When the team then passed ultraviolet laser light through the fibers, no solarization damage showed - even at output powers of 125 mW at 313-nm laser wavelengths (several times the intensity of the group's quantum computing experiments).
The tests appeared to show "long-term resistance" to this type of damage, concluded the team in its research paper. Furthermore, very little of the laser light that was transmitted was lost through the fibers.
Hydrogen-treated fibers can be used to transmit a wide range of infrared, visible and ultraviolet wavelengths of light. They can transfer ultraviolet light between separate optical tables and also help "clean up" misshapen beams, says the NIST research group.