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

Abstract-Generation of broadband terahertz pulses via optical rectification in a chalcopyrite CdSiP2 crystal

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

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-42-19-3920

We report on the generation of broadband (0.07–6 THz) terahertz (THz) radiation via optical rectification in a ⟨110⟩  CdSiP2$⟨110⟩{\mathrm{CdSiP}}_2$ (CSP) crystal pumped by a 50 fs, 780 nm central wavelength optical pulse. By measuring the THz phase refractive index and the optical pump group refractive index, good phase matching can be achieved for a crystal thickness ≲200  μm$\lesssim 200\mathrm{\mu m}$. Due to this crystal’s high second order nonlinearity and low absorption losses, it is envisioned that THz generation from CSP could be further enhanced by confining the optical pump pulse to sub-wavelength waveguides.

© 2017 Optical Society of America

Abstract-Terahertz electro-optic detection using a ⟨012⟩-cut chalcopyrite ZnGeP2 crystal

B. N. Carnio1,a), S. R. Greig1, C. J. Firby1, K. T. Zawilski2, P. G. Schunemann2 and A. Y. Elezzabi


http://scitation.aip.org/content/aip/journal/apl/108/26/10.1063/1.4955040


The electro-optic detection capabilities of a 〈012〉-cut chalcopyrite ZnGeP2 (ZGP) crystal is investigated in the terahertz (THz) frequency regime. Our experiments attest that ZGP exhibits low THz losses and dispersion, and that phonon-polariton effects are too weak to perturb the THz pulse. Additionally, ZGP is shown to have excellent phase matching between an optical probe pulse and a THz pulse. For a 1080 μm thick ZGP crystal, this phase matching yields a detection bandwidth 1.3 times greater than ZnTe and 4.8 times greater than ZnSe and GaP. Thus, ZGP has promising applications in THz time-domain spectroscopy.