Fig. 1. Schematic diagram. (a) Polarized THz-TDS system with an adjustable magnetic field. (b) THz wave transfer through the sample. (c) Magnetic Faraday rotation effect. (d) Device formed after packaging a sample.

Fig. 2. (a) Photograph of La:YIG sample. (b) SEM image. (c) XRD pattern of La:YIG and GGG film. (d) Hysteresis curve of a La:YIG sample.

Fig. 3. (a) Time domain THz pulses of air and La:YIG film on GGG substrate. (b) Effective refractive index of La:YIG. (c) Transmission and absorption coefficient of one sample under different EMFs. (d) Transmission and absorption coefficient of different numbers of samples (stacked together).

Fig. 4. (a), (b) Phase change of left-handed rotation and right-handed rotation of one La:YIG sample at different EMFs. (c) Faraday rotation angle spectra of one La:YIG sample under the EMF range from −0.22 to 0.22 T. (d) Verdet constant spectrum of La:YIG calculated from the polarization rotation angle at an EMF of 0.22 T.

Fig. 5. (a), (b) Phase change of left-handed rotation and right-handed rotation of different numbers of YIG samples (stacked together) under ±0.22  T. (c) Faraday rotation angle spectra of different numbers of YIG samples (stacked together) under ±0.22  T. (d) Faraday rotation angle changes with the number of sample stacks. (e), (f) Polarization states of the transmitted THz wave through one to four stacked La:YIG films at 0.6 THz under ±0.22  T.

Fig. 6. (a) ±45°  LP time domain THz pulses of four stacked La:YIG films under the EMF of ±0.22  T. (b) −45° transmission under the EMF of ±0.22  T. (c) +45° transmission under the EMF of ±0.22  T. (d) Isolation of four stacked La:YIG films under the EMF of 0.22 T.

Fig. 7. (a), (b) Transmission of eight La:YIG samples (stacked together) with ±45° linearly polarized light. (c) Faraday rotation angle spectra of eight La:YIG samples (stacked together) under the EMF range from −0.26 to 0.26 T. (d) Isolation of eight stacked La:YIG films under the EMF range from 0 to 0.26 T. (e), (f) Polarization states of the transmitted THz wave through eight stacked La:YIG films at 0.6 THz from 0 to ±0.26  T. (g) Faraday rotation angle spectrum of eight La:YIG samples changes with magnetic field. (h) Isolation of eight stacked La:YIG films changes with magnetic field.

Table 1. Optimized Growth Parameters for La:YIG Films

Table 2. Y, La, Fe, O Mole Fractions Obtained by EPMA from the Surface of La:YIG Sample (in %)