Wavelength and temperature characteristics of BiYbIG film/YIG crystal composite structure for magneto-optical applications

摘要

We report the wavelength and temperature characteristics of novel Bi-substituted rare-earth iron garnet films grown on a YIG substrate by a modified liquid phase epitaxy (LPE) technique. The Faraday-rotation spectrum was measured by the magneto-optically modulated dual-frequency technique with the wavelength varied from 800 nm to 1700 nm. The resultant Bi_(0.37)Yb_(2.63)Fe_5O_(12) (BiYbIG) LPE film/YIG crystal structure showed an increased Faraday-rotation coefficient due to Bi~(3+)-ion doping on the dodecahedral sites of the iron garnet without increasing absorption loss; therefore, a good magneto-optical figure of merit, defined by the ratio of Faraday rotation and optical absorption loss, has been achieved (21.5 deg/dB and 30.2 deg/dB at 1300-nm and 1550-nm wavelengths, respectively, at room temperature). In addition, since the Yb~(3+) and Y~(3+) ions provide opposite contributions to the wavelength and temperature characteristics of the Faraday rotation, the resultant BiYbIG LPE film/YIG crystal structure showed a flat Faraday-rotation curve versus wavelength and temperature. The Faraday-rotation wavelength coefficient was reduced to 0.06 %m at 1550-nm wavelength. The Faraday-rotation temperature derivative was reduced to 0.006deg/℃ at 1300-nm wavelength and 0.007 deg/℃ at 1550-nm wavelength, respectively.