Li Yi-Lei, Li Teng-Fei, Wen Qi-Ye, Fan Fei, Yang Qing-Hui, Chang Sheng-Jiang
Opt Express. 2020 Jul 6;28(14):21062-21071. doi: 10.1364/OE.395668.
The wafer-scale La:YIG single crystal thick films were fabricated on a three-inch gadolinium gallium garnet (GGG) substrate by liquid phase epitaxy method. The terahertz (THz) optical and magneto-optical properties of La:YIG film were demonstrated by THz time domain spectroscopy (THz-TDS). The results show that a high refractive index of approximately 4.09 and a low absorption coefficient of 10-50 cm from 0.1 to 1.6 THz for this La:YIG film. Moreover, the THz Faraday rotation effect of La:YIG film was measured by the orthogonal polarization detection method in THz-TDS system, which can be actively manipulated by a weak longitudinal magnetic field of up to 0.155 T. With 5 samples stacked together, the Faraday rotation angle varies linearly from -15° to 15°, and the Verdet constant of La:YIG is about 100 °/mm/T within the saturation magnetization. This magneto-optical single crystal thick film with large area shows low loss, high permittivity and strong magneto-optical effect in the THz regime, which will be widely used in magneto-optical polarization conversion, nonreciprocal phase shifter and isolator for THz waves.
采用液相外延法在三英寸钆镓石榴石（GGG）衬底上制备了晶圆级镧铁石榴石（La:YIG）单晶厚膜。通过太赫兹时域光谱（THz-TDS）对La:YIG薄膜的太赫兹光学和磁光特性进行了表征。结果表明，该La:YIG薄膜在0.1至1.6太赫兹范围内具有约4.09的高折射率和10 - 50 cm的低吸收系数。此外，在THz-TDS系统中采用正交偏振检测法测量了La:YIG薄膜的太赫兹法拉第旋转效应，该效应可通过高达0.155 T的弱纵向磁场进行主动调控。5个样品堆叠在一起时，法拉第旋转角在-15°至15°之间呈线性变化，且La:YIG在饱和磁化强度下的Verdet常数约为100 °/mm/T。这种大面积磁光单晶厚膜在太赫兹波段表现出低损耗、高介电常数和强磁光效应，将广泛应用于太赫兹波的磁光偏振转换、非互易移相器和隔离器。
