Active modulation of refractive index by stress in the terahertz frequency range.

Experimental tests are presented to investigate the stress effect on terahertz (THz) waves with a THz time-domain spectroscopy system. Through the Jones matrix method, an experimental principle is derived according to the experimental system. Experimental results indicate the linear relationship between a polytetrafluoroethylene refractive index and applied stress. The result can be applied to the active modulation of a refractive index or phase of a THz wave.