Topology optimization and fabrication of photonic crystal structures

Borel, Peter Ingo; Harpøth, Anders; Frandsen, Lars Hagedorn; Kristensen, Martin; Shi, Peixiong; Jensen, Jakob Søndergaard; Sigmund, Ole

doi:10.1364/opex.12.001996

Cited by 284 publications

(149 citation statements)

References 18 publications

(16 reference statements)

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“…: +45-45254256, Fax: +45-45931975 E-mail: sigmund@mek.dtu.dk lithography equipment. The topology optimized waveguide [1] is shown at the top and the manufactured device is shown at the bottom 1 . It is clearly seen that all holes have become too big due to the badly focussed e-beam and that many small features have merged together in the physical structure.…”

Section: Introductionmentioning

confidence: 99%

Manufacturing tolerant topology optimization

2009

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In this paper we present an extension of the topology optimization method to include uncertainties during the fabrication of macro, micro and nano structures. More specifically, we consider devices that are manufactured using processes which may result in (uniformly) too thin (eroded) or too thick (dilated) structures compared to the intended topology. Examples are MEMS devices manufactured using etching processes, nano-devices manufactured using e-beam lithography or laser micro-machining and macro structures manufactured using milling processes. In the suggested robust topology optimization approach, under-and over-etching is modelled by image processing-based "erode" and "dilate" operators and the optimization problem is formulated as a worst case design problem. Applications of the method to the design of macro structures for minimum compliance and micro compliant mechanisms show that the method provides manufacturing tolerant designs with little decrease in performance. As a positive side effect the robust design formulation also eliminates the longstanding problem of onenode connected hinges in compliant mechanism design using topology optimization.

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Section: Introductionmentioning

confidence: 99%

Manufacturing tolerant topology optimization

2009

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“…PhCW structures with 20-40 nm useful optical bandwidths have previously been demonstrated [3,10,11]. Recently, Borel et al [12] have demonstrated that a new inverse design method, topology optimisation, can be utilised to dramatically increase the bandwidth of a PhCW component. However, some of the holes in these components have special sizes and shapes that currently cannot be manufactured using deep UV lithography and, thus, cannot currently be mass fabricated.…”

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confidence: 99%

Bandwidth engineering of photonic crystal waveguide bends

Borel¹,

Frandsen²,

Harpøth³

et al. 2004

Electron. Lett.

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An effective design principle has been applied to photonic crystal waveguide bends fabricated in silicon-on-insulator material using deep UV lithography resulting in a large increase in the low-loss bandwidth of the bends. Furthermore, it is experimentally demonstrated that the absolute bandwidth range can be adjusted in a post-fabrication thermal oxidation process.Introduction: The planar photonic crystal waveguide (PhCW) has numerous potential applications because of its unique capability to control the propagation of light by utilising the photonic bandgap (PBG) effect [1,2]. This effect allows the interaction between light and the PhCW to take place on a minute scale [3,4]. Thereby, the overall size of optical components based on PhCW structures may be greatly minimised and, correspondingly, device packing density increased. Recent advances in deep UV lithography at 248 nm [5] have made mass fabrication of optical ultra-compact PhCW devices viable by employing existing fabrication methods commonly encountered in the semiconductor electronics industry.Research has now reached a level where existing fabrication technologies allow manufacture of PhCW structures with low propagation losses [6][7][8][9]. Hence, there is presently worldwide focus on the design and fabrication of PhCW structures possessing adequate bandwidths. PhCW structures with 20-40 nm useful optical bandwidths have previously been demonstrated [3,10,11]. Recently, Borel et al. [12] have demonstrated that a new inverse design method, topology optimisation, can be utilised to dramatically increase the bandwidth of a PhCW component. However, some of the holes in these components have special sizes and shapes that currently cannot be manufactured using deep UV lithography and, thus, cannot currently be mass fabricated. Except for these topology-optimised structures, no bandgap-based PhCW components have been demonstrated with satisfactory performance in a broad wavelength range.In this Letter, we present an alternative design strategy, which also leads to large bandwidths of PhCW bends, and that is suitable for fabrication utilising deep UV lithography. Furthermore, we demonstrate a simple experimental procedure employing thermal oxidation on how to tune the absolute position of the operational bandwidth for an already fabricated batch of samples.

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“…Furthermore, it is hard to get a novel structure, just by changing the structural parameters. In order to determine the design automatically from desired characteristics, many optimization methods have been developed, such as genetic algorithm [16], topology optimization [17], and WFM method [9]- [15]. WFM method is an optimization algorithm based on beam propagation method (BPM) [18], [19], which determine the optimum index profiles from the ideal output field.…”

Section: Wavefront Matching Methodsmentioning

confidence: 99%

A Review of PLC-Based Broadband Two-Mode Multi/Demultiplexer Designed by Wavefront Matching Method

Taguchi

Fujisawa

Yamashita

et al. 2018

IEICE Trans. Electron.

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SUMMARYA PLC based mode multi/demultiplexer based on asymmetric directional coupler has advantages in terms of compactness, mass productivity, low insertion loss, and matured reliability. However, it has relatively large wavelength dependence due to the difference of coupling length. To expand the bandwidth, we have designed two-mode (LP 01 /LP 11a ) multi/demultiplexer by wavefront matching method and demonstrated the broadband and low-loss characteristics. This paper reviews the device design by wavefront matching method and investigates the mechanism of its broadband characteristics. key words: WFM method, PLC, MDM, mode multi/demultiplexer

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Topology optimization and fabrication of photonic crystal structures

Cited by 284 publications

References 18 publications

Manufacturing tolerant topology optimization

Manufacturing tolerant topology optimization

Bandwidth engineering of photonic crystal waveguide bends

A Review of PLC-Based Broadband Two-Mode Multi/Demultiplexer Designed by Wavefront Matching Method

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