Influence of the bus waveguide on the linear and nonlinear response of a taiji microresonator

Year: 2021

Authors: Franchi Riccardo; Biasi Stefano; de las Heras Alberto Munoz; Ghulinyan Mher; Carusotto Iacopo; Pavesi Lorenzo

Autors Affiliation: Univ Trento, Dept Phys, Nanosci Lab, Via Sommar 14, I-38123 Povo, Italy; Univ Trento, INO CNR BEC Ctr, I-38123 Trento, Italy; Univ Trento, Dept Phys, I-38123 Trento, Italy; Fdn Bruno Kessler, Sensors & Devices, I-38123 Trento, Italy

Abstract: We study the linear and nonlinear response of a unidirectional reflector where a nonlinear breaking of the Lorentz reciprocity is observed. The device under test consists of a racetrack microresonator, with an embedded S-shaped waveguide, coupled to an external bus waveguide (BW). This geometry of the microresonator is known as “”taiji”” microresonator (TJMR). Here, we show that a full description of the device needs to consider also the role of the BW, which introduces (i) Fabry-Perot oscillations (FPOs) due to reflections at its facets, and (ii) asymmetric losses, which depend on the actual position of the TJMR. At sufficiently low powers the asymmetric loss does not affect the unidirectional behavior, but the FP interference fringes can cancel the effect of the S-shaped waveguide. However, at high input power, both the asymmetric loss and the FPOs contribute to the redistribution of energy between counterpropagating modes within the TJMR. This strongly modifies the nonlinear response, giving rise to counter-intuitive features where, due to the FP effect and the asymmetric losses, the BW properties can determine the violation of the Lorentz reciprocity and, in particular, the difference between the transmittance in the two directions of excitation. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Journal/Review: OPTICS EXPRESS

Volume: 29 (19)      Pages from: 29615  to: 29630

KeyWords: OPTICAL ISOLATION; CIRCULATORS; BACKSCATTERING; BISTABILITY; RECIPROCITY; PHOTONICS; ISOLATORS; TAPER
DOI: 10.1364/OE.434239

Citations: 3
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