Frequency-tunable terahertz wave generation via excitation of phonon-polaritons in GaP

Abstract

High-power, wide-frequency-tunable terahertz waves were generated based on difference-frequency generation in GaP crystals with small-angle noncollinear phase matching. The tunable frequency range was as wide as 0.5-7 THz, and the peak power remained high, near 100 mW, over most of the frequency region. The tuning properties were well described by the dispersion relationship for the phonon-polariton mode of GaP up to 6 THz. We measured the spectra of crystal polyethylene and crystal quartz with high resolution using this THz-wave source.

Terahertz Wave Generation from GaP with Continuous Wave and Pulse Pumping in the 1–1.2 μm Region

“…The pulse generator pumped at 1 mm region uses a Q-switched Nd:YAG laser with 10 Hz repetition rate and a -BaB 2 O 4 (BBO)-based OPO pumped by using the YAG laser. [19][20][21] Its pulse width and line width were 11 ns and 90 MHz for the 1.064-mm fundamental beam of the YAG laser, and 6 ns and less than 6 GHz for the 1.035-1.064 mm tunable beam of the OPO laser, respectively. The energies of the YAG and OPO were 3 mJ with 3 mm diameter.…”

“…17,18) Using a GaP Raman laser, a 12.1-THz wave was generated at a power of 3 W. 6,7) Recently, wide-frequency-tunable highpower THz waves have been generated from GaP by pumping with a Q-switched YAG laser and an optical parametric oscillator (OPO) at 1 mm. [19][20][21] THz waves were generated using difference frequency generation (DFG) via the excitation of phonon-polaritons based on the Raman effect in GaP. THz waves were also obtained using Cr:forsterite lasers at 1.2-1.3 mm, 22) which have the merits of simple structure, easy maintenance, and low cost compared to pumping using YAG and an OPO.…”

Analysis of the specific vibration modes of goethite (α-FeOOH) by terahertz spectroscopy and calculations of the vibration frequencies of a single molecule using density functional theory

“…It has since become possible to make measurements over a wide range of tunable frequencies using difference frequency generation (DFG) crystals, which have high nonlinear optical effects. Thus, we have devoted much attention to studying this phenomenon [2][3][4] . As THz spectroscopy has developed, the infrared activities of many organic and biological substances have been reported [5][6][7][8][9][10] ; however, the infrared activity of…”

Fabrication and Characterization of GaP Photonic Crystals for Terahertz Wave Application

“…The most THz-wave sources are based on photoconductive antenna, quantum cascade lasers, or non-linear optical effects such as difference frequency generation (DFG), optical parametric oscillation, and optical rectification. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] The DFG can produce tunable, narrow linewidth, and high power THz-waves with ns-pulsed as well as CW operation. 18,19) The THz-waves can be generated at room temperature.…”

“…[7][8][9][10][12][13][14]20) In addition, our previous works have generated THz-waves with bulk GaP crystals under a small-angle non-collinear phase matched DFG condition. [7][8][9] By using the THz wave source, a frequencytunable THz spectrometer has constructed, and the THz spectra of important biomolecules (e.g. sugars, nucleosides, nucleotides, amino acids, etc.)…”