Coherent tunable THz-wave generation from LiNbO3 with monolithic grating coupler

Abstract

Coherent THz-wave generation is demonstrated utilizing a grating coupler fabricated on the surface of a LiNbO3 crystal pumped by a Q-switched Nd:YAG laser. Wide tunability, sharp directivity, and high efficiency were achieved.

Optical DFG-based 60 GHz signal generation by using a LiTaO₃ rectangular waveguide

“…Advanced photonic technologies developed for optical fiber communication systems (high-gain optical amplifiers, high-speed optical modulators, optical frequency shifters, optical comb generators, and sharp cut optical filters) are also applicable to control/ improve DFG responses. Several studies on signal generation based on DFG have been reported [5,6,7]. However, there are still some challenging issues: precise control of the phase matching condition between the lightwaves and MMW/THz signals, and the coupling of the generated MMW/THz signals to other circuits.…”

Recent progress on terahertz generation based on difference frequency generation: from power scaling to compact and portable sources (Invited Paper)

“…Aside from optical rectifications, other parametric processes in nonlinear crystals can be relatively efficient in converting optical pulses into THz waves. For example, based on the THz parametric oscillation in a LiNbO 3 crystal [12] , the output power on the level of ∼mW has been generated in the range of 140−290 µm (1.03−2.14 THz). By mixing two coherent infrared laser beams in nonlinear-optical crystals such as GaSe [13−15] , ZnGeP 2 [16−18] , and GaP [19,20] , the THz waves have been efficiently generated with extremely-wide tuning ranges and very high peak powers as well as high conversion efficiencies.…”

Terahertz-Wave Parametric Sources

“…The terahertz wave parametric generation is based on an optical parametric process in a nonlinear crystal (Sussman, 1970;Pietrup et al, 1975). The principles of the terahertz wave parametric generator (TPG) (Shikata et al, 2000;Sato et al, 2001;Shikata et al, 2002) and the terahertz wave parametric oscillator (TPO) (Kawase et al, 1996; allow building systems that are not only compact but also operate at room temperature, making them suitable as practical sources. In principle, both a narrow linewidth and a wide tunability are possible in injection-seeded TPG/TPO (is-TPG/TPO) systems with single-longitudinal-mode near-infrared lasers as seeders Imai et al, 2001).…”