Embedded ring resonators for microphotonic applications

Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA.
Optics Letters (Impact Factor: 3.29). 10/2008; 33(17):1978-80. DOI: 10.1364/OL.33.001978
Source: PubMed


We propose a new type of optical resonator that consists of embedded ring resonators (ERRs). The resonators exhibit unique amplitude and phase characteristics and allow designing compact filters, modulators, and delay elements. A basic configuration of the ERRs with two rings coupled in a point-to-point manner is discussed under two operating conditions. An ERR-based microring modulator shows a high operation speed up to 30 GHz. ERRs with distributed coupling are briefly described as well. (C) 2008 Optical Society of America.

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Available from: Lin Zhang, Oct 07, 2015
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    • "The mode numbers, m 1 and m 2 , are set to be approximately 900 and 681, respectively, corresponding to a radius of ∼57 μm of Ring 2. Coupled mode theory [42] is used to analyze the transfer characteristics of the embedded rings (see [27] for more details). If m 1 and m 2 are both integers, the resonant wavelengths of Ring 1 and Ring 2 are aligned, and EIT-like responses or mode splitting are seen [25], [27]. When the resonant wavelengths of Ring 1 and Ring 2 are offset, we observe asymmetric Fano lineshapes, as shown in Fig. 2. The Fano effect in the embedded rings results from the interference between the optical fields in Ring 1 and Ring 2, where the resonance of Ring 1 serves as the continuum and the resonance of Ring 2 is analogous to a discrete state [29], [30]. "
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    ABSTRACT: High-$Q$ microresonators play an important role in developing fully integrated, highly sensitive, and cost-effective bio/chemical sensors. The Fano effect in doubly resonant physical systems may be used to improve sensing performance. In this paper, we show that coupled optical resonators (sometimes termed photonic molecules) in an embedded configuration can significantly enhance the sensitivity and limit of detection (LOD) of on-chip sensors by producing a reversed Fano effect. Improvement of one order in sensitivity, as compared to a sensor based on conventional Fano effect, can be achieved using embedded high- $Q$ resonators on a CMOS-compatible platform. We estimate the LOD by taking into account thermal drift, optical losses (material absorption, scattering, substrate leakage and bending loss), laser intensity noise, linewidth and frequency jitter, and link and detector signal-to-noise ratio (SNR). The overall LOD is found to be as low as 3.24 × 10$^{-8}$ RIU. Moreover, in the proposed sensor based on embedded rings, intensity SNR is no longer the limiting factor of the LOD, which could be further lowered with better thermal control and laser frequency stability.
    IEEE Journal of Selected Topics in Quantum Electronics 12/2013; 20(3):5200110. DOI:10.1109/JSTQE.2013.2294465 · 2.83 Impact Factor
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    • "The outer ring is coupled with parallel waveguides, and the amplitude coupling coefficients in the four coupling regions are labeled t 1 , t 2 , t 3 , and t 4 , as shown in Fig. 1(b). The embedded rings work at a resonant wavelength of 1.55 μm, and mode numbers are set to be m 1 = 101 and m 2 = 70 to enable the EIT-like effect [6]. Transfer function is calculated at the " out " port using coupled mode theory [7]. "
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    ABSTRACT: We study both the intensity and phase responses in embedded rings operated in analogy to electromagnetically induced transparency. Different phase regimes have been identified, which correspond to different optical nonlinear enhancement characteristics.
    Lasers and Electro-Optics Pacific Rim (CLEO-PR), 2013 Conference on, Kyoto; 06/2013
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    • "This requires less memory and computation time than the method in [29]. However, in some other cases [18], [28], [45], the optical fields at different parts of the rings have to be solved to examine the optical waves' interference and evolution. One need to use either the model in [29] or a modified version of the model in [42] by combining it with the steady-state coupledmode theory in [46], both of which require a time step less than one cavity round-trip time. "
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    ABSTRACT: We numerically analyze the characteristics of silicon-based microring modulators consisting of a single-ring resonator. Performance of the devices as digital intensity modulators is examined in terms of extinction ratio, pulsewidth, frequency chirp, spectral broadening, and signal quality. Three types of the modulators built in single-waveguide under-/overcoupling and dual-waveguide configurations are discussed. We show that cavity dynamics significantly affect the modulation properties. Data transmission performance over single-mode fibers is also presented. A silicon microring modulator with negative chirp could achieve 0.8 dB power penalty in 80-km fiber transmission without dispersion compensation.
    IEEE Journal of Selected Topics in Quantum Electronics 03/2010; 16(1-16):149 - 158. DOI:10.1109/JSTQE.2009.2027816 · 2.83 Impact Factor
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