Table of Contents
Deep-Ultraviolet Solid-State Lasers: Applications and Impact
Over the past decade, the generation of DUV radiation by solid-state lasers, including fiber lasers, has been extensively studied. Deep-UV light sources have a wide range of applications. Because shorter-wavelength light has higher photon energy, the photon energy of deep ultraviolet light sources is sufficient to kill bacteria and viruses and decompose harmful, stable substances, such as dioxin and polychlorinated biphenyls (PCBs), which have caused serious environmental problems worldwide. Therefore, deep-UV light sources are used in water purification, sterilization, and environmental protection equipment. In addition, since the focal point of light decreases with decreasing wavelength, deep ultraviolet light sources have potential for use in high-density optical data recording and nanofabrication technology. Furthermore, they are also expected to be used in medical procedures and analytical instruments.
Limitations of Conventional DUV Light Sources
Most DUV fiber lasers used are gas light sources, such as mercury lamps or excimer lasers. They contain toxic substances, which cause serious environmental problems, and are large in size and low in efficiency and reliability. Moreover, the emission wavelengths are fixed at 254 nm for mercury lamps and 193 nm for ArF excimer lasers.
Emerging Deep-UV Laser Technologies for Industry and Science
New laser sources operating in the deep-ultraviolet (DUV) range (the wavelength region below 300 nm) can help to streamline industrial and scientific applications. For example, state-of-the-art semiconductor lithography and inspection are currently performed using somewhat expensive pulsed excimer lasers at 193 nm. Actinic inspection of exposed wafers—that is, inspection at the exposure wavelength can benefit from continuous-wave light sources.
Scientific and Quantum Applications of Tunable DUV Lasers
On the scientific side, applications include angle-resolved photoemission spectroscopy (ARPES), where researchers need high photon energies for the measurement of large portions of the Brillouin zone of new materials. In addition, new applications are emerging in the field of Raman spectroscopy, such as protein structural analysis and Raman spectroscopy beyond the solar background.
In quantum technology, tunable DUV lasers are used for high-resolution spectroscopy and laser cooling. For instance, atomic clocks can be improved considerably with direct access to optical transitions in aluminum or mercury ions, and one can possibly realize nuclear optical clocks with thorium in the near future.