Abstract-Efficient optical-to-terahertz conversion in large-area InGaAs photo-Dember emitters with increased indium content

 

I. E. Ilyakov, B. V. Shishkin, V. L. Malevich, D. S. Ponomarev, R. R. Galiev, A. Yu. Pavlov, A. E. Yachmenev, S. P. Kovalev, M. Chen, R. A. Akhmedzhanov,  R. A. Khabibullin, 

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-46-14-3360

In this Letter, optical-to-terahertz (THz) conversion of 800 nm femtosecond laser pulses in large-area bias-free InGaAs emitters based on photo-Dember (PD) and lateral photo-Dember (LPD) effects is experimentally investigated. We use metamorphic buffers to grow sub-micrometer thick In𝑥Ga1−𝑥As${\mathrm{I}\mathrm{n}}_x{\mathrm{G}\mathrm{a}}_{1-x}\mathrm{A}\mathrm{s}$ layers with indium mole fractions 𝑥=0.37$x=0.37$, 0.53, and 0.70 on a GaAs substrate. A strong enhancement of THz output energy with an increase of indium content is observed. On the surface of the sample providing the strongest emission (𝑥=0.7$x=0.7$), we have fabricated a 1.5cm2$1.5{\mathrm{c}\mathrm{m}}^2$ area of asymmetrically shaped metallic grating for LPD emission. This LPD emitter allows achieving high conversion efficiency of 0.24⋅10−3$0.24\cdot {10}^{-3}$ and a broad generation bandwidth of up to 6 THz. We also demonstrate that there is no significant difference in the conversion efficiency when operating at 1 and 200 kHz repetition rates. Our results show that large-area LPD emitters give a convenient, competitive way to generate intense high-repetition-rate THz pulses.

© 2021 Optical Society of America

Abstract-Terahertz Dielectric Properties of Polycrystalline MgAl2O4 Spinel Obtained by Microwave Sintering and Hot Pressing

S. V. Egorov, A. A. Sorokin, I. E. Ilyakov, B. V. Shishkin, E. A. Serov, V. V. Parshin, K. I. Rybakov, S. S. Balabanov, A. V. Belyaev

https://link.springer.com/article/10.1007%2Fs10762-019-00582-4

This paper describes the fabrication of polycrystalline magnesium aluminate spinel (MgAl2O4) by microwave sintering and hot pressing and the investigation of its dielectric properties in the millimeter-wave and terahertz frequency range. The dielectric properties were studied in the frequency range 50–300 GHz using a spectrometer based on an open Fabry–Perot resonator with a high quality factor and in the range 0.6–3.3 THz using the time-domain spectroscopy method. The terahertz radiation was generated as a result of air breakdown using two-color laser pulses with carrier wavelengths of 800 and 400 nm. The dielectric characteristics of MgAl2O4 ceramics obtained from high-purity nanosized powders by microwave sintering and by hot pressing are compared. The refractive index of the materials varies from 2.85 to 2.95, and the dielectric loss tangent increases from 1.5 × 10−4 to 1.5 × 10−2 within the frequency range 0.05–3.3 THz. The possible use of magnesium aluminate spinel for millimeter-wave and terahertz applications is discussed.

Abstract-Electro-optic sampling of terahertz waves by laser pulses with an edge-cut spectrum in birefringent crystal

I. E. Ilyakov, G. Kh. Kitaeva, B. V. Shishkin, and R. A. Akhmedzhanov

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-42-9-1704

We demonstrate a terahertz detection technique based on variations of the energy of femtosecond laser pulses with an edge-cut spectrum in birefringent electro-optic crystal—periodically poled lithium niobate (PPLN). The method is compared with the standard electro-optic detection scheme utilizing GaP crystal. The experimental results show that the studied technique is suited for use with birefringent crystals and allows one to achieve a much better response to the terahertz wave radiation at quasi-phase-matching frequencies of PPLN.

© 2017 Optical Society of America

Abstract-Terahertz radiation from bismuth surface induced by femtosecond laser pulses

I. E. Ilyakov, B. V. Shishkin, D. A. Fadeev, I. V. Oladyshkin, V. V. Chernov, A. I. Okhapkin, P. A. Yunin, V. A. Mironov, and R. A. Akhmedzhanov
https://www.osapublishing.org/ol/abstract.cfm?uri=ol-41-18-4289

We report on the first experimental observation of terahertz (THz) wave generation from bismuth mono- and polycrystalline samples irradiated by femtosecond laser pulses. Dependencies of the THz signal on the crystal orientation, optical pulse energy, incidence angle, and polarization are presented and discussed together with features of the sample surfaces. The optical-to-THz conversion efficiency was up to two orders of magnitude higher than for metal at a moderate fluence of ∼1  mJ/cm2. We also found nonlinear effects not previously observed using other metal and semiconductor materials: (a) asymmetry of THz response with respect to a half-turn of a sample around its normal, (b) THz polarization control by orientation of the sample surface, and (c) strong enhancement of optical-to-THz conversion after structuring of a sample with optically large-scale parallel strips pattern.

© 2016 Optical Society of America

Full Article  |  PDF Article