Global optimization of an encapsulated Si/SiO2 L3 cavity with a 43 million quality factor

Vasco, J. P.; Savona, Vincenzo

doi:10.21203/rs.3.rs-197762/v1

Cited by 2 publications

(3 citation statements)

References 45 publications

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“…This leads to a significantly lower number of simulations needed to obtain an optimal structure. For comparison, a recent work reports on the application of GME to a similar cavity design by using a global optimization procedure on a comparable number of parameters, which converged to a result that is comparable with ours (18 times larger Q but 3.5 times larger V , in a structure with a slightly larger refractive index contrast in ref ). Crucially, the global optimization required 800 000 evaluations, while our gradient-based optimization converges after 131 function and gradient evaluations (equivalent to 262 forward-only evaluations in terms of computational time), which highlights the computational advantage of AD for this problem.…”

Section: Discussionsupporting

confidence: 77%

“…This is fundamentally linked to the use of finite-difference frequency-domain simulations, which have significant difficulties in resolving sharp resonances that shift in frequency during the course of optimization. In contrast, global optimization methods using the GME have already proven extremely useful when applied to PhC cavities, ,,, both, because of the speed of the individual computation and because high- Q resonances actually represent the condition under which the approximation of the method works best. Here, we have moved one step further, leveraging our differentiable implementation of GME to perform a gradient-based optimization.…”

Section: Discussionmentioning

confidence: 99%

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Inverse Design of Photonic Crystals through Automatic Differentiation

et al. 2020

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Gradient-based inverse design in photonics has already achieved remarkable results in designing small-footprint, high-performance optical devices. The adjoint variable method, which allows for the efficient computation of gradients, has played a major role in this success. However, gradient-based optimization has not yet been applied to the mode-expansion methods that are the most common approaches to studying periodic optical structures such as photonic crystals. This is because, in such simulations, the adjoint variable method cannot be defined as explicitly as in standard finite-difference or finite-element time-or frequency-domain methods. Here, we overcome this gap through the use of automatic differentiation, which is a generalization of the adjoint variable method to arbitrary computational graphs. We implement the planewave expansion and the guided-mode expansion methods using an automatic differentiation library, and we show that the gradient of any simulation output can be computed efficiently and in parallel, with respect to all input parameters. We then use this implementation to optimize the dispersion of a photonic crystal waveguide, and the quality factor of an ultrasmall cavity in a lithium niobate slab. This extends photonic inverse design to an entirely new class of simulations, and more broadly highlights the importance that automatic differentiation could play in the future for tracking and optimizing complicated physical models.

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Section: Discussionsupporting

confidence: 77%

Section: Discussionmentioning

confidence: 99%

Inverse Design of Photonic Crystals through Automatic Differentiation

et al. 2020

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“…38,60 Of particular importance will be development of an optimization routine that reduces the computation time needed to evaluate the cavity Q for the geometry in each iteration; methods such as machine learning and guided mode expansion may be useful in this respect. 41,60 Finally, we note that this design can be expanded to include more than two regions of independent local electric field tunability separated by monolithic cuts. A good starting point for such a design may be a waveguide structure that takes advantage of periodic boundary conditions and optimized waveguide ends.…”

Section: Phc Cavity Resultsmentioning

confidence: 99%

Computational Design of a Split Cavity with Localized Independent Electric Field Tunability

Carfagno,

Herrmann,

Wang

et al. 2023

ACS Photonics

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Cavity-mediated strong coupling is an essential element for quantum photonic technologies, but there are multiple challenges to creating scalable device platforms in which multiple matter-based qubits can be strongly coupled to a single cavity. Among these challenges is the inherent inhomogeneity in ensembles of matter-based qubits, which necessitates independent tuning of each qubit into resonance with the mode of the cavity. We present a new design for a photonic crystal split cavity that enables independent electric field tuning of two distinct qubits based on indium arsenide quantum dots in a gallium arsenide heterostructure. Using finite difference time domain simulations, we alter the cavity geometry and the local arrangement of photonic crystal holes to optimize the cavity quality factor. We achieve a simulated quality factor of 20,000, which is comparable to values that have been used to demonstrate strong coupling. We further show that distinct electric fields can be applied to the two qubits with negligible cross talk. The result demonstrates the viability of a new approach to coupling multiple qubits to a single cavity and opens the door for both further numerical optimization and experimental realization of this new paradigm.

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Global optimization of an encapsulated Si/SiO2 L3 cavity with a 43 million quality factor

Cited by 2 publications

References 45 publications

Inverse Design of Photonic Crystals through Automatic Differentiation

Inverse Design of Photonic Crystals through Automatic Differentiation

Computational Design of a Split Cavity with Localized Independent Electric Field Tunability

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