Optical properties of polycrystalline KRS-5 fiber at individual CO_2 laser lines: magnetooptic effects

A polycrystalline KRS-5 fiber is experimentally investigated for magnetooptic effects such as the Faraday and Voigt effects, extinction coefficient, and natural depolarization at individual vibrational–rotational transitions of 10.6- and 9.6-μm bands in a CO2 laser. The results are, on the average, a Verdet constant of 0.033 and 0.024 min/cm · G, a Voigt constant of 2.5 × 10−6 min/cm · G2, a natural depolarization of ~0.36 and 0.34 deg/cm, and an extinction coefficient of 1.1 and 1.5 dB/m at 10.6- and 9.6-μm bands, respectively. Both magnetooptic effects are also compared with the theoretical estimates obtained using known parameters. The extinction coefficient follows the inverse-square dependence on the wavelength, supporting the remarks by Harrington and Sparks.