Well known fused silica fibers possess by high transmission in a broad spectral range from 180nm up to 2.2μm and can be used for Near-InfraRed (NIR-) spectroscopy or for laser power delivery of Diode, Nd- or Ho-lasers. As silica fiber transmission is limited for a longer wavelengths by fundamental multi-phonon absorption wing – the other types of materials were used to fabricate fibers for Mid InfraRed range, i.e. for wavelengths above 2,2μm and up to 16μm. Hollow Waveguides (HW), including band-gap photonic crystals can be also used for flexible delivery of Mid IR-radiation, but with some limitations in their spectral attenuation and in beam divergence caused by HW-structure and bending radii.
© 2014 Optical Society of AmericaPDF Article