Accurate Complex Refractive Index with Standard Deviation of ZnTe Measured by Terahertz Time Domain Spectroscopy

Abstract

Accurate complex refractive index of ZnTe crystal in terahertz spectral region from 0.2 to 3.5 THz is obtained by measuring three samples with different thickness using transmission terahertz time-domain spectroscopy. Each sample is measured a number of times and the mean and standard deviation (SD) of the complex refractive index are calculated to quantify the random errors in the measurement. The ratios of SD to mean of the real and imaginary parts of the refractive index are approximately 1.0×10-4 and 1.2×10-2 at 1 THz respectively. The absorption coefficient of our ZnTe sample is found to be comparable with or smaller than the values reported in previous literatures.

Direct comparison of time-resolved terahertz spectroscopy and Hall Van der Pauw methods for measurement of carrier conductivity and mobility in bulk semiconductors

“…Static THz-TDS measurements revealed that the THz transmission magnitude was nearly equivalent to a measurement of dry purged air (implying zero THz absorption when corrected for surface reflections in the THz spectral range 0.3 THz to 2.1 THz according to the index of refraction and Fresnel equation) for all the samples except ZnTe. For the ZnTe sample studied, the THz transmission was significantly attenuated and yielded a peak THz absorption at 1.7 THz, in agreement with other THz absorption measurements [41]. This THz-TDS absorption in ZnTe is not likely the result of free charge carriers but a low energy phonon absorption in the THz range (there are two weak absorptions < 2 THz, but the strong optical phonon band is centered at 5 THz).…”

Polarization-Sensitive Electro-Optic Sampling of Elliptically-Polarized Terahertz Pulses: Theoretical Description and Experimental Demonstration

“…For evaluating a(Ω) and β 1 (Ω), we measure the complex refractive indices of the two EO crystals in the terahertz frequency range and the group velocities of the probe pulse inside the EO crystals. The obtained values of the complex refractive indices and the group velocities for the two EO crystals are similar to those reported in previous works [14,104,105]. Since χ (2) is proportional to r 41 , we used the values r 41 = 4 pm/V for ZnTe and r 41 = 1 pm/V for GaP [14].…”

Evaluation of Crystallinity and Hydrogen Bond Formation in Stereocomplex Poly(lactic acid) Films by Terahertz Time-Domain Spectroscopy

“…From the terahertz time-domain electric-field waveforms obtained with and without sample, it is possible to calculate the complex refractive index spectrum N ̂(ω) = n(ω) + ik(ω) of the sample as a function of the optical angular frequency, ω. 42 The complex dielectric constant that is defined as ε(ω) = ε′(ω) + iε″(ω) 43 can be calculated from N ̂(ω) by using the relation ε(ω) = {N ̂(ω)} 2 . Figure 2 shows the real (ε′) and imaginary parts (ε″) of the dielectric functions of the 16 PLA films in the terahertz frequency range measured by our THz-TDS system.…”