THz Wave Modulators: A Brief Review on Different Modulation Techniques
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THz Wave Modulators: A Brief Review on Different Modulation Techniques Marco Rahm & Jiu-Sheng Li & Willie J. Padilla
Received: 9 July 2012 / Accepted: 23 October 2012 / Published online: 9 November 2012 # Springer Science+Business Media New York 2012
Abstract We review different techniques for modulation of the electromagnetic properties of terahertz (THz) waves. We discuss various approaches for electronic, optical, thermal and nonlinear modulation in distinct material systems such as semiconductors, graphene, photonic crystals and metamaterials. The modulators are classified and compared with respect to modulation speed, modulation depth and categorized by the physical quantity they control as e.g. amplitude, phase, spectrum, spatial and temporal properties of the THz wave. Based on the review paper, the reader should obtain guidelines for the proper choice of a specific modulation technique in view of the targeted application. Keywords Terahertz wave modulators . Metamaterials, graphene . Electronic modulation . All-optical modulation . Photonic crystal modulators . Nonlinear tuning of metamaterials . Magnetic field tuning 1 Introduction Optics is one of the most foundational technologies fostering innovation and economic growth in a wealth of application disciplines. Certainly the most crucial technological advance in the field of optics was the invention of the laser [1, 2] with applications spanning from material processing and machining, welding and drilling [3] to laser-optical precision
M. Rahm (*) Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Erwin-Schroedinger-Strasse, 67663 Kaiserslautern, Germany e-mail: [email protected] M. Rahm Fraunhofer Institute for Physical Measurement Techniques IPM, Heidenhofstrasse 8, 79110 Freiburg, Germany J.-S. Li Centre for THz Research, China Jiliang University, Hangzhou 310018, China e-mail: [email protected] W. J. Padilla Department of Physics, Boston College, 140 Commonwealth Ave, Chestnut Hill, MA 02467, USA e-mail: [email protected]
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J Infrared Milli Terahz Waves (2013) 34:1–27
measurement systems and metrology [4], laser spectroscopy [5, 6], bio sensing [7] and much more. Information technology continues to strongly benefit from laser technology which enabled the transition from comparably slow electronic telecommunication systems to alloptical, spectrally broadband optical communication networks with high data transmission rates up to multiple Terabits per second [8–11]. A key to high data transmission rates in optical fibers has been the development of efficient amplitude and/or phase modulators which are used to encode information in the carrier wave. However, such components do not only play a decisive role for optical networks, but are also irreplaceable for real-time manipulation of light and the technological advancement of adaptive optics in a wider context [12]. For example, modulators can be used to control the amplitude, phase, polarization state, spatial propagation direction, pulse shape, pulse length and ma
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