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arXiv · 1505.07291

Position-squared coupling in a tunable photonic crystal optomechanical cavity

Taofiq K. Paraiso·Mahmoud Kalaee·Leyun Zang·Hannes Pfeifer·Florian Marquardt·Oskar Painter
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Abstract

We present the design, fabrication, and characterization of a planar silicon photonic crystal cavity in which large position-squared optomechanical coupling is realized. The device consists of a double-slotted photonic crystal structure in which motion of a central beam mode couples to two high-Q optical modes localized around each slot. Electrostatic tuning of the structure is used to controllably hybridize the optical modes into supermodes which couple in a quadratic fashion to the motion of the beam. From independent measurements of the anti-crossing of the optical modes and of the optical spring effect, the position-squared vacuum coupling rate is measured to be as large as 245 Hz to the fundamental in-plane mechanical resonance of the structure at 8.7MHz, which in displacement units corresponds to a coupling coefficient of 1 THz/nm$^2$. This level of position-squared coupling is approximately five orders of magnitude larger than in conventional Fabry-Perot cavity systems.

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Taofiq K. Paraiso, Mahmoud Kalaee, Leyun Zang, Hannes Pfeifer, Florian Marquardt, Oskar Painter. 2015-05-27. Position-squared coupling in a tunable photonic crystal optomechanical cavity. https://doi.org/10.1103/physrevx.5.041024

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