Broadband THz modulation characteristics of vanadium dioxide thin film prepared on glass substrate

For the applications of vanadium dioxide (VO2) thin film in terahertz tunable functional devices, the vanadium dioxide VO2 thin film was prepared by magnetron sputtering technique on K9 glass substrate, and the crystal structure was characterized by X-ray diffraction (XRD). Spectral characteristics and their variations of terahertz (THz) reflection and transmission signal passing through the sample at different temperatures were studied by the THz time domain spectroscopy system (THz-TDS) equipped with heating device. The experimental results indicated that the semiconductor-metal transition of VO2 thin film occurred with the increase of the heating temperature and showed excellent modulation to the broadband THz wave. The modulation depth was dependent on the THz frequency. The THz wave amplitude modulation depth of reflection power and transmission showed remarkable fluctuation in the band of 0.3-0.5 THz. The transmittance of THz wave was larger in the low frequency band than that in the high frequency band, and the modulation depth varied in the range of 35%-65%. The thin film was prepared simply and had high quality, which can be applied to THz modulator functions such as devices and switches.