New method to determine the refractive index and the absorption coefficient of organic nonlinear crystals in the ultra-wideband THz region

Seigo Ohno, Katsuhiko Miyamoto, Hiroaki Minamide, Hiromasa Ito

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

A method for simultaneously measuring the refractive index and absorption coefficient of nonlinear optical crystals in the ultra-wideband terahertz (THz) region is described. This method is based on the analysis of a collinear difference frequency generation (DFG) process using a tunable, dual-wavelength, optical parametric oscillator. The refractive index and the absorption coefficient in the organic nonlinear crystal DAST were experimentally determined in the frequency range 2.5-26.2 THz by measuring the THz-wave output using DFG. The resultant refractive index in the x-direction was ∼2.3, while the absorption spectrum was in good agreement with FT-IR measurements. The output of the DAST-DFG THzwave source was optimized to the phase-matching condition using the measured refractive index spectrum in THz region, which resulted in an improvement in the output power of up to a factor of nine.

Original languageEnglish
Pages (from-to)17306-17312
Number of pages7
JournalOptics Express
Volume18
Issue number16
DOIs
Publication statusPublished - 2010 Aug 2

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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