Krypton fluoride laser
A krypton fluoride laser (KrF laser) is a particular type of
KrF and ArF excimer lasers are widely incorporated into high-resolution
Theory
A krypton fluoride laser absorbs energy from a source, causing the
- 2 Kr + F
2 → 2 KrF
The complex can undergo spontaneous or stimulated emission, reducing its energy state to a metastable, but highly repulsive ground state. The ground state complex quickly dissociates into unbound atoms:
- 2 KrF → 2 Kr + F
2
The result is an exciplex laser which radiates energy at 248 nm, near the ultraviolet portion of the spectrum, corresponding with the energy difference between the ground state and the excited state of the complex.
Example Systems
There have been several of these lasers built for ICF experiments; examples include:[6]
- Los Alamos built a KrF laser in 1985 to prove test firing of beam with an energy level of 1.0 × 104 joules. This was part of the larger Aurora laser research effort that looked at CO2 lasers and other systems.
- Nike Laser. The Laser Plasma Branch of the Naval Research Laboratory completed a KrF laser called the Nike laser that can produce about 4.5 × 103 joules of UV energy output in a 4 nanosecond pulse. The NIKE laser was switched to an Argon fluoride laserafter 2013 to show the impact of going to shorter (193 nm) wavelengths.
- Naval Research Laboratory built the Electra laser and Nike to prove out both KrF and ArF lasers for ICF approaches. In 2013, Electra demonstrated 90,000 shots over 10 hours of operation.[7]
- Rutherford Appleton Laboratory built the Sprite and Titania KrF lasers[8]
- Japan's Electrotechnical Laboratory built the Ashura and Super Ashura KrF lasers.[9]
- China Institute for Atomic Energy had a laser before the middle-1990's
- Livermore National Laboratory developed a KrF laser and amplifier known as a Raman Amplifier Pumped by Intensified Excimer Radiation (RAPIER) system system.[10]
Applications
This laser has also been used to produce soft X-ray emission from a plasma, through irradiation by brief pulses of this laser light. Other important applications include manipulating of various materials such as plastic, glass, crystal, composite materials and living tissue. The light from this UV laser is strongly absorbed by lipids, nucleic acids and proteins, making it useful for applications in medical therapy and surgery.
Microelectronics
The most widespread industrial application of KrF excimer lasers has been in deep-ultraviolet
Fusion Research
The KrF laser has been used in nuclear fusion energy research since the 1980s. This laser offers several advantages:[7]
- High rate repetition shots - because the KrF is made using gas it does not heat up, allowing for higher shot rates.
- Higher beam uniformity
- Relatively shorter wavelength for improved ICF compression.
Safety
The light emitted by the KrF is invisible to the human eye, so additional safety precautions are necessary when working with this laser to avoid stray beams. Gloves are needed to protect the skin from the potentially carcinogenic properties of the UV beam, and UV goggles are needed to protect the eyes.
See also
- Argon fluoride laser
- Nike laser
- Laser
- Krypton difluoride
- Krypton
- Fluorine
- Excimer laser
- Excimer lamp
- Photolithography
- Excimer
References
- ^ Basting, D. and Marowsky,G., Eds., Excimer Laser Technology, Springer, 2005.
- ^ S2CID 43335574.
- ^ a b c Jain, K. "Excimer Laser Lithography", SPIE Press, Bellingham, WA, 1990.
- ^ a b La Fontaine, B., "Lasers and Moore's Law", SPIE Professional, Oct. 2010, p. 20.
- ^ Samsung Starts Industry's First Mass Production of System-on-Chip with 10-Nanometer FinFET Technology; https://news.samsung.com/global/samsung-starts-industrys-first-mass-production-of-system-on-chip-with-10-nanometer-finfet-technology
- ^ "Proceedings of the 4th international workshop on KrF laser technology" Annapolls Maryland, May 2, 1994 to May 5th 1994
- ^ a b Obenschain, Stephen, et al. "High-energy krypton fluoride lasers for inertial fusion." Applied optics 54.31 (2015): F103-F122.
- ^ Divall, E. J., et al. "Titania—a 1020 W cm− 2 ultraviolet laser." Journal of modern optics 43.5 (1996): 1025-1033.
- ^ Okuda, I., et al. "Performance of theSuper-ASHURA'main amplifier." Fusion engineering and design 44.1-4 (1999): 377-381.
- ^ https://lasers.llnl.gov/multimedia/publications/pdfs/etr/1979_06.pdf
- ^ Basting, D., et al., "Historical Review of Excimer Laser Development," in Excimer Laser Technology, D. Basting and G. Marowsky, Eds., Springer, 2005.
- ^ American Physical Society / Lasers / History / Timeline
- ^ SPIE / Advancing the Laser / 50 Years and into the Future
- ^ U.K. Engineering & Physical Sciences Research Council / Lasers in Our Lives / 50 Years of Impact Archived 2011-09-13 at the Wayback Machine
External links
- Laser fusion energy
- Nike KrF Laser Facility
- Nikon KrF Archived 2005-09-07 at the Wayback Machine