The New Composite Rare Earth Iron Garnet Films Preparation And Properties Of Liquid Phase Epitaxy

With advances of optical communication and information processing system, extensive investigations on magneto-optical materials and devices have been carried out. To prevent unstable oscillation of laser diodes due to backward beam, optical isolators are indispensable in these systems. In the near infrared wavelength range, Yttrium iron garnet (YaFesOn or YIG) and Bismuth-substituted garnet films or bulk single crystals such as gadolinium-bismuth iron garnet (Gd3.xBixFe5Oi2 or GdBilG) are often used as Faraday rotator. However, their shortcoming is apparent: the Faraday rotation coefficient 9 F of YIG is too small for practical use; Faraday rotation of Bi-substituted garnet reveals wavelength and temperature dependencies.In recent years, growing attention is being focused on wavelength division multiplexing optical communication as a promising means of high-speed, mass-scale communication. To realize these systems, wideband & temperature-stabilized optical isolators are essential, which in turn require Faraday rotators capable of ensuring a Faraday rotation stable against wavelength and temperature variation. Bi-substituted magneto-optical materials, have attracted much attention much attention due to their strong enhance MO effects, small absorption loss and high physical-chemical stability.Recent research and development on magneto-optical materials and devices, especially on rare-earth iron garnet single crystals thin film are reviewed in this thesis. Investigations on the thin film growth and magneto-optical properties of a new YbIG iron garnet thin film on Bi substituted iron garnet substrate is extensively carried out. Faraday rotation spectra have been measured on samples at room temperature with the model CGX-1 FR test apparatus improved by ourselves using the magneto-optic modulated double-frequency method. From the viewpoint of material designing, the temperature and wavelength dependence of Faraday rotation for substituted iron garnets is improved by using a combination of some rare-earth iron garnets with opposite signs for the temperature and wavelength coefficients of Faraday rotation atroom temperature.The thesis research accomplished the skeleton design of the growth of Bi:YIG and YbIG rare-earth iron garnet, the analysis of the phase graph and establishment of the formula. The YbIG grow on Bi:YIG substrate is first produced by liquid phase epitaxy (LPE) which is the materials suitable for the broad band isolator in the optic-fiber systems. Thin film of Bi-substituted mixed rare-earth iron garnet and YbIG has been grown by LPE with an improved flux method in which Bi2Os (former)and PbO(later) are used as the main flux. At last we grow the YbIG on BiYIG. The detail experiment procedure is reviewed, and the microstructure is analyzed by XRD and SEM/EDX and the magneto-optical properties of thin film are tested by Faraday Rotation Testing System. Secondly the thesis firstly put forward a concept that combing of two types of Bi3+-substituted rare-earth iron garnets with opposite signs of temperature and wavelength coefficients for the Faraday rotation through the structure combination by LPE used temperature stabilized and wideband optical isolators employing in WDM optical fiber communication systems.