Terahertz time-domain spectroscopy of congruent LiNbO₃ and LiTaO₃ crystals

Abstract

The complex dielectric constants of congruent LiNbO3 and LiTaO3 single crystals in a THz frequency region have been determined directly by using broadband terahertz time-domain spectroscopy (THz-TDS) with reflection configuration. We have successfully extracted the accurate complex dielectric constants by using corrected phase information derived from the transmission measurement results. The lowest E(TO1) phonon modes of both crystals have been observed clearly. On the other hand, additional bands at approximately 2.5 THz below the lowest A 1(TO1) mode frequency have been observed. These bands have also been reported by Raman and hyper-Raman spectroscopy and attributed to intrinsic defects in congruent crystals. According to the experimental results that these additional bands were observed at almost the same frequency on Raman, hyper-Raman, and THz-TDS, these bands are suggested to be assigned as a first-order scattering process.

Broadband terahertz time-domain spectroscopy of ferroelectric LiTaO3: Phonon-polariton dispersion

“…In Figs. 2 (a) and (b), the observed values by both the transmission and reflection measurements were shown with the curves fitted by the damped harmonic oscillator (DHO) model [9]. For the ordinary refractive index which is related to the E(x) modes, the real and imaginary parts of ordinary refractive index clearly show the sharp resonance at the lowest-frequency TO mode frequency near =4.2 THz.…”

“…Using these equations, we determined the complex polariton dispersion relations of the lowest A 1 (z), E(x) modes for a congruent ferroelectric lithium tantalite crystal using the observed values of the complex refractive index by the broadband THz-TDS at room temperature [9].…”

“…where 4A The poled congruent lithium tantalite crystals were measured by broadband THz-TDS and the complex dielectric constants for E//c and E//a components was determined by H. Igawa et al [9]. First, the complex refractive index was calculated as shown in Figs.…”

Boson peak dynamics of glassy glucose studied by integrated terahertz-band spectroscopy

“…The temperature was varied from 14 to 320 K using a liquid-helium flow cryostat system (Helitran LT-3B, Advanced Research Systems) [8,50,64]. We employed the Cherenkov-type MgO-doped LiNbO 3 emitter (TAS7500SU, Advantest Corp.) [8,[64][65][66] for the room-temperature broadband measurement.…”

Broadband Terahertz Time-Domain Spectroscopy of Archaeological Baltic Amber

“…THz-TDS has been adequately recognized to be one of trustworthy tools for spectroscopic measurements of far-infrared properties of materials like dielectrics [4,5], semiconductors [4,6], superconductors [7], gases [8], liquids [8] and glassy materials [9,10]. In the present study, we performed broadband terahertz time-domain spectroscopy to investigate the dynamical properties of Baltic amber in the THz range.…”