Terahertz-Magnetic-Field Induced Ultrafast Faraday Rotation of Molecular Liquids

Abstract

Rotation of the plane of the polarization of light in the presence of a magnetic-field, known as the Faraday rotation, is a consequence of the electromagnetic nature of light and has been utilized in many optical devices. Current efforts aim to realize the ultrafast Faraday rotation on a subpicosecond time scale. Thereby, the Faraday medium should allow an ultrafast process by which in the presence of an ultrashort intense magnetic-field, the light polarization rotates. We meet these criteria by applying an intense single cycle THz magnetic-field to simple molecular liquids and demonstrate the rotation of the plane of polarization of an optical pulse traversing the liquids on a sub-picosecond time scale. The effect is attributed to the deflection of an optically induced instantaneous electric polarization under the influence the THz magnetic-field. The resolved Faraday rotation scales linearly with the THz magnetic-field and quadratically with the molecular polarizability.When a linearly polarized electromagnetic (EM) wave, along with a magnetic-field, propagates through an optically transparent medium its plane of polarization rotates. This effect is termed Faraday rotation and has played an important role in elucidating the EM nature of light [1]. It has also been extensively used in many devices including optical switches [2], optical communication systems [3], quantum memories [4], nuclear magnetic resonance spectrometers [5] and light modulators [6]. Further applications of Faraday rotators rely on the development in two main areas, introducing new Faraday media or exploring new features for existing materials and increasing the modulation speed of Faraday rotators.So far there has been great progress in finding new materials with large Faraday rotation, such as nitride semiconductor alloys [7,8], two-dimensional electron gases [9], graphene [10] and organic molecules [11]. However, a sub-picosecond light modulation requires an inherently ultrafast microscopic process whereupon the light polarization rotates [12]. For example, in semiconductors the modulation rate is limited by the mobility of the charge carriers and the relaxation processes in the bulk material [13]. Moreover, ultrafast magnetic switching with terahertz (THz) clock rate is required, a goal that is far to reach with current magnetic pulses with temporal duration of about hundreds of picoseconds [14,15].To increase the modulation speed of the Faraday rotators, we take advantage of the magnetic-field of single cycle THz EM pulses. The potential of THz pulses has so far been explored to observe [16] and in some cases control the low-energy elementary excitations in liquids [17,18], solids [19], and gases [20] on ultrafast timescale. In these examples, the THz electric-field interacts with the IR-active dipolar excitations of the samples, while the THz magnetic-field interaction is neglected because of its much weaker interaction energy. However, recent studies have shown the great potential of the THz magnetic fields for ultrafast Faraday rotat...

1.4‐mJ High Energy Terahertz Radiation from Lithium Niobates

“…Nevertheless, many THz science and applications are primarily focused on weak-field passive detection of matter, based on linear light-matter interaction process. On the other hand, intense THz field-induced nonlinearly active control of matter [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] is, to some extent, still out of reach due to the shortage of highly efficient, and stable THz sources. It results in many mesoscale/microscopic physics and phenomena almost inaccessible.…”

“…It results in many mesoscale/microscopic physics and phenomena almost inaccessible. Although ultrafast microjoule-scale THz sources have already exhibited their powerful capabilities in electron acceleration and manipulation [37][38][39][40][41][42] , fieldinduced phase transition [17][18][19][20] , and nonlinear THz phenomena [24][25][26][27][28][29][30][31] in a wide range of materials and structures, the demand for millijoule-level THz sources has not yet been fully met, especially when facing the dawn of extreme THz science overwhelmingly growing to the next frontier in nonlinear optics 29,43 .…”

Time-resolved terahertz–Raman spectroscopy reveals that cations and anions distinctly modify intermolecular interactions of water

“…The THz–Raman experiment is performed in the TKE configuration, whose details are given elsewhere 43 , 71 , 72 . As shown schematically in Fig.…”

Вращение Атомно-Молекулярной Частицы, Находящейся В Поле Линейно Поляризованной Световой Волны И Постоянном Электрическом Или Магнитном Поле

“…Для нас интересен вопрос о возможности использования в качестве указанных полей переменного электрического и магнитного поля световых частот. Ответ на него дает анализ физики таких явлений, как " оптический эффект Холла" [5] и родственный ему ( " counterpart" [6]) эффект Фарадея в растворах органических молекул, наблюдавшийся при использовании терагерцевых импульсов магнитного поля [6]. В последней работе для объяснения полученных результатов была привлечена феноменологическая модель динамического молекулярного эффекта Холла (ДМЭХ).…”