Stability and lifetime improvements of UV fibers for new applications

Abstract

Two years ago, UV-improved (UVI-) fibers were described for the first time. These fibers show significantly reduced UV-absorption around 215 nm during the transmission of UV-light from different UV-sources like deuterium-lamps, excimer-lasers and frequency-doubled tunable dyelasers. This improvement has been realized due to a passivation of the generated UV-defects by gas-doping.Depending on the ambient temperature and the fiber diameter, the lifetime of UV-stability was quite different in these first generation UVI-fibers. This long-term behavior has been studied with different illuminations, temperatures and fiber diameters; there is a good agreement between experimental and theoretical data. Additional modifications have lead to a further improvement in the long-term stability. The predicted lifetime of these UVI2-fibers (<1 50 pm) of the second generation at room temperature is longer than I year. In addition, a short-term behavior was observed using diode-array spectrometer. In this case, the influence of temperature on the transient induced losses is significant and will be described.

Silica–silica polyimide buffered optical fibre irradiation and strength experiment at cryogenic temperatures for 355nm pulsed lasers

“…Due to out-gassing of hydrogen, the spectral transmission changes in the non-cooled fibre section outside the cryostat [14]. The result is applicable to unloaded fibres since hydrogen loading should not play any role on opto-accoustic shock.…”

“…The samples regarding the irradiation tests are shown in Table 4. Hydrogen diffuses out from the loaded fibres if they are kept a long period of time at room temperature [14,15]. All the fibres were installed at the same time and the tests last for one week.…”

Improvement of optical damage in specialty fiber at 266 nm wavelength

“…As expected, the hydrogen-loaded fibers have significantly improved UV resistance. The UV-induced losses at 266 nm will be extremely low for quite a while (expectation for 100 µm core diameter at room temperature: > 9 months), because out-gassing of hydrogen out of the core region is significantly reduced [30] due to the large cladding-to-core ratio (CCR). The losses in a 2 m long fiber were mainly below 0.1 dB at this wavelength.…”

Transient and steady state radiation responses of solarization-resistant optical fibers

“…The high radiation sensitivity at these wavelengths of optical fibers or bulk glasses is explained by the fact that most of the created defects absorb and sometimes emit in this spectral region (see [6] or Manuscript [7] for a review). For other applications than those encountered in the nuclear fields, optical fibers with improved and stable UV transmission are needed to transport relative high amounts of UV light (< 300 nm) e-g. for spectroscopy (absorption, fluorescence), process control and optical sensing applications [8], [9]. Previous studies [8] showed that the transmission of high-power UV light inside a fiber can be sufficiently aggressive to generate large amounts of absorbing defects leading to a strong darkening phenomenon; an effect looking quite comparable to the RIA observed during exposure to ionizing particles.…”

“…Previous studies [8] showed that the transmission of high-power UV light inside a fiber can be sufficiently aggressive to generate large amounts of absorbing defects leading to a strong darkening phenomenon; an effect looking quite comparable to the RIA observed during exposure to ionizing particles. This UV-induced effect is usually called "solarization" [8], [9]. To reduce the amplitude of this effect, several manufacturers have developed "solarization-resistant" products; it means a better tolerance to the UV (λ<300 nm)-induced effects in silica, resulting in a more stable transmission of light with time.…”