Tunable Interferometers Driven by Coherent Surface Acoustic Phonons
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Tunable Interferometers Driven by Coherent Surface Acoustic Phonons
Antonio Crespo-Poveda,1 Alberto Hernández-Mínguez,2 Klaus Biermann,2 Abbes Tahraoui,2 Bernardo Gargallo,3 Pascual Muñoz,3 Paulo V. Santos,2 Andrés Cantarero,1 and Maurício M. de Lima, Jr.1 1
Materials Science Institute, University of Valencia, P.O. Box 2208, ES46071 Valencia, Spain Paul Drude Institute for Solid State Electronics, Hausvogteiplatz 5-7, DE10117 Berlin, Germany 3 iTEAM Research Institute, Polytechnic University of Valencia, Camino de Vera s/n, ES46022 Valencia, Spain 2
ABSTRACT We demonstrate a compact tunable photonic modulator driven by surface acoustic waves (SAWs) in the low GHz frequency range. The device follows a well-known Mach-Zehnder interferometer (MZI) structure with three output channels, built upon multi-mode interference (MMI) couplers. The light continuously switches paths between the central and the side channels, avoiding losses and granting a 180◦-dephasing synchronization between them. The modulator was monolithically fabricated on (Al,Ga)As, and can be used as a building block for more complex photonic functionalities. It can also be implemented in other material platforms such as Silicon or (In,Ga)P. Light modulated at multiples of the fundamental acoustic frequency can be accomplished by adjusting the applied acoustic power. An excellent agreement between theory and experiment is achieved. INTRODUCTION A great effort has been made during the past decades to increase the integration level in photonic circuits. An incipient exponential trend in the number of integrated elements per chip resembling the well known Moore’s law can be appreciated. Although integration levels of up to a few thousands of components per chip have been accomplished [1], the absence of a standarized integration technology has prevented so far photonic integrated circuits from reaching the same development followed by its electronic counterpart. It is then of superlative importance to search for devices that are at the same time compatible with nowadays integration technology, fast, compact and inexpensive. The external control of light propagation inside the devices allows also for a reduction in the dimensions, favouring the integration and giving rise to novel functionalities. A promising approach consists of using coherent surface acoustic phonons in the form of a SAW to modulate single or multiple ridge or slot waveguides (WGs) through the acousto-optical effect [2-5], with the possibility of addressing several devices with the same SAW beam. This method presents an excellent compromise between speed and size, and can be implemented in almost any material platform such as Silicon, (In,Ga)P or LiNbO3. In this contribution, we present a three output photonic modulator driven by SAWs in the low GHz
1651 Downloaded from https://www.cambridge.org/core. Columbia University Libraries, on 15 Aug 2017 at 21:11:32, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1557/adv.2016.2
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