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

Abstract

The terahertz (THz) region, which lies between the microwave and infrared regions, offers a wealth of untapped potential. We generated widely frequency-tunable coherent THz waves from GaP crystal pumped using continuous-wave (CW) semiconductor lasers and compared it with pulse pumping using Q-switched high-power lasers at 1-1.2 mm. THz wave generation was based on difference-frequency generation via the excitation of phonon-polaritons in GaP. CW THz waves were generated from GaP by enhancing the power density of the pumping light from semiconductor lasers. The power and phase-matched condition for THz wave generation are discussed with respect to the pumping method compared to pulse pumping. Semiconductor lasers have light power stability with a narrow linewidth. Therefore, CW THz waves can be used as a light source in high-resolution THz spectroscopy, as well as in multichannel communication.

Vibrational spectroscopic analysis of theophylline in a pharmaceutical granulation process using near-, mid- and far-infrared/terahertz spectroscopy

“…For FIR/THz measurement, a Gallium-Phosphorus (GaP) THz signal generator system equipped with a pyroelectric DTGS detector was used. This THz generator system was developed and constructed by Nishizawa et al [1,2]. The measurement range, resolution and scan number were set at 12500 cm -1 to 4000 cm -1 , 2 cm -1 and 128, for a NIR measurement, 4000 cm -1 to 400 cm -1 , 1 cm -1 and 64 for a MIR measurement, respectively.…”

Photoconductivity of Er-doped InAs quantum dots embedded in strain-relaxed InGaAs layers with 1.5 µm cw and pulse excitation

“…On the other hand, studies on the operation of PC antennas for various wavelengths for 1.0-1.2 µm bands were reported. [20][21][22][23] In future, PC antennas operating with various wavelengths are expected with the further progress of fs pulse lasers with a wider range of wavelengths.…”

THz-Wave Generation from GaP THz Photonic Crystal Waveguides under Difference-Frequency Mixing

“…Many coherent THz sources, based on photoconductive antenna, quantum cascade lasers, and non-linear optical effects, such as difference-frequency generation (DFG), optical parametric oscillation, and optical rectification, have been developed for these applications [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. In particular, DFG can be used to produce tunable, narrow linewidth, high-power THz-waves, with ns-pulsed and continuous wave (CW) operation at room temperature [18,19]. This DFG process is suitable for wave sources used in THz telecommunications and in-situ security screening.…”