Abstract-Backward terahertz difference frequency generation via modal phase-matching in a planar LiNbO3 waveguide

B. N. Carnio and A. Y. Elezzabi

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-45-13-3657

The backward difference frequency generation process is used to produce narrowband terahertz radiation via modal phase-matching in a SiO2-LiNbO3${\mathrm{S}\mathrm{i}\mathrm{O}}_2\text{-}{\mathrm{L}\mathrm{i}\mathrm{N}\mathrm{b}\mathrm{O}}_3$-air planar waveguide. The TM0${\mathrm{T}\mathrm{M}}_0$ pump mode, TE0${\mathrm{T}\mathrm{E}}_0$ signal mode, and TE0${\mathrm{T}\mathrm{E}}_0$ or TE2${\mathrm{T}\mathrm{E}}_2$ idler modes are selected to satisfy the backward difference frequency generation phase-matching condition, thus allowing narrowband (i.e., <100GHz$<100\mathrm{G}\mathrm{H}\mathrm{z}$ linewidth) terahertz radiation generation in the spectral range of 2.4–3.2 THz. To date, this is the first investigation of terahertz radiation generation in a waveguide via the modal phase-matched backward difference frequency generation process.

© 2020 Optical Society of America

Abstract-Dependence on excitation polarization and crystal orientation for terahertz radiation generation in a BaGa4Se7 crystal

B. N. Carnio, E. Hopmann, K. T. Zawilski, P. G. Schunemann, and A. Y. Elezzabi

(a) Schematic showing the setup implemented to perform optical rectification THz radiation generation experiments using the BaGa4Se7 crystal. xr, yr, and zr define the reference coordinates. (b) An illustration of a BaGa4Se7 crystal unit cell. The near-IR excitation electric field, 𝐸⃗ 𝑒𝑥𝑐${\overrightarrow{E}}_{exc}$, and the generated terahertz radiation electric field, 𝐸⃗ 𝑇𝐻𝑧${\overrightarrow{E}}_{THz}$, polarizations are shown with respect to the crystal orientation.

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-28-10-15016

Optical rectification is experimentally investigated in a biaxial BaGa4Se7 crystal by considering various combinations of near-infrared excitation polarizations and crystal orientations. The highest terahertz radiation is produced along the Z crystallo-physical direction of the BaGa4Se7 crystal. Despite the optical complexity of the BaGa4Se7 crystal in the terahertz spectral regime, this systematic experimental investigation determines the optimal excitation polarization and crystal orientation for the optical rectification process.

© 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Optical rectification in a chalcopyrite AgGaSe2 crystal for broadband terahertz radiation generation

B. N. Carnio, K. T. Zawilski, P. G. Schunemann, and A. Y. Elezzabi

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-44-11-2867

We report on optical rectification in a ⟨110⟩$⟨110⟩$ AgGaSe2${\mathrm{AgGaSe}}_2$ crystal that produces terahertz (THz) electric field pulses across the broad frequency range of 0.02–4 THz. Due to the large coherence length of the AgGaSe2${\mathrm{AgGaSe}}_2$ crystal (>4$>4$ times larger than that of CdSiP2${\mathrm{CdSiP}}_2$ and ZnGeP2${\mathrm{ZnGeP}}_2$), in-phase THz radiation is produced over the entire crystal thickness of 485 μm. Furthermore, THz time-domain spectroscopy is used to determine the ordinary and extraordinary refractive indices and extinction coefficients of the uniaxial AgGaSe2${\mathrm{AgGaSe}}_2$ crystal across the broad spectral range of 0.5–2.9 THz, encompassing several phonon resonances.

© 2019 Optical Society of America