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945 KiB

Open AccessArticle

A Multithread Nested Neural Network Architecture to Model Surface Plasmon Polaritons Propagation

by Giacomo Capizzi, Grazia Lo Sciuto, Christian Napoli and Emiliano Tramontana

Micromachines 2016, 7(7), 110; https://doi.org/10.3390/mi7070110 - 30 Jun 2016

Cited by 35 | Viewed by 4766

Surface Plasmon Polaritons are collective oscillations of electrons occurring at the interface between a metal and a dielectric. The propagation phenomena in plasmonic nanostructures is not fully understood and the interdependence between propagation and metal thickness requires further investigation. We propose an ad-hoc [...] Read more.

Surface Plasmon Polaritons are collective oscillations of electrons occurring at the interface between a metal and a dielectric. The propagation phenomena in plasmonic nanostructures is not fully understood and the interdependence between propagation and metal thickness requires further investigation. We propose an ad-hoc neural network topology assisting the study of the said propagation when several parameters, such as wavelengths, propagation length and metal thickness are considered. This approach is novel and can be considered a first attempt at fully automating such a numerical computation. For the proposed neural network topology, an advanced training procedure has been devised in order to shun the possibility of accumulating errors. The provided results can be useful, e.g., to improve the efficiency of photocells, for photon harvesting, and for improving the accuracy of models for solid state devices. Full article

(This article belongs to the Special Issue Micro/Nano Photonic Devices and Systems)

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5058 KiB

Open AccessArticle

Robust Design of an Optical Micromachine for an Ophthalmic Application

by Ingo Sieber, Thomas Martin and Ulrich Gengenbach

Micromachines 2016, 7(5), 85; https://doi.org/10.3390/mi7050085 - 06 May 2016

Cited by 11 | Viewed by 6160

Abstract

This article describes an approach to the robust design of an optical micromachine consisting of a freeform optics, an amplification linkage, and an actuator. The robust design approach consists of monolithic integration principles to minimize assembly efforts and of an optimization of the [...] Read more.

This article describes an approach to the robust design of an optical micromachine consisting of a freeform optics, an amplification linkage, and an actuator. The robust design approach consists of monolithic integration principles to minimize assembly efforts and of an optimization of the functional components with respect to robustness against remaining assembly and manufacturing tolerances. The design approach presented involves the determination of the relevant tolerances arising from the domains manufacturing, assembly, and operation of the micromachine followed by a sensitivity analysis with the objective of identifying the worst offender. Subsequent to the above-described steps, an optimization of the functional design of the freeform optics with respect to a compensation of the effects of the tolerances is performed. The result leads to a robust design of the freeform optics and hence ensures a defined and optimal minimum performance of the micromachine in the presence of tolerances caused by the manufacturing processes and the operation of the micromachine. The micromachine under discussion is the tunable optics of an ophthalmic implant, an artificial accommodation system recently realized as a demonstration model at a scale of 2:1. The artificial accommodation system will be developed to replace the human crystalline lens in the case of a cataract. Full article

(This article belongs to the Special Issue Micro/Nano Photonic Devices and Systems)

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1554 KiB

Open AccessArticle

Minimally Intrusive Optical Micro-Strain Sensing in Bulk Elastomer Using Embedded Fabry-Pérot Etalon

by Jungwook Paek, Qiang Li, In Ho Cho and Jaeyoun Kim

Micromachines 2016, 7(4), 61; https://doi.org/10.3390/mi7040061 - 06 Apr 2016

Cited by 2 | Viewed by 5963

Abstract

A variety of strain sensors have been developed to measure internal deformations of elastomeric structures. Strain sensors measuring extremely small mechanical strain, however, have not yet been reported due mainly to the inherently intrusive integration of the sensor with the test structure. In [...] Read more.

A variety of strain sensors have been developed to measure internal deformations of elastomeric structures. Strain sensors measuring extremely small mechanical strain, however, have not yet been reported due mainly to the inherently intrusive integration of the sensor with the test structure. In this work, we report the development of a minimally intrusive, highly sensitive mechanical strain transducer realized by monolithically embedding a Fabry-Pérot (FP) etalon into a poly(dimethylsiloxane) (PDMS) block test structure. Due to the extreme sensitivity of the FP resonance condition to the thickness of the spacer layer between the two reflectors, the limit of detection in the mechanical deformation can be as low as ~110 nm with a 632.8 nm laser used as the probing light. The compatibility of PDMS with additive fabrication turned out to be the most crucial enabling factor in the realization of the FP etalon-based strain transducer. Full article

(This article belongs to the Special Issue Micro/Nano Photonic Devices and Systems)

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4131 KiB

Open AccessArticle

Holographic Fabrication of Designed Functional Defect Lines in Photonic Crystal Lattice Using a Spatial Light Modulator

by Jeffrey Lutkenhaus, David Lowell, David George, Hualiang Zhang and Yuankun Lin

Micromachines 2016, 7(4), 59; https://doi.org/10.3390/mi7040059 - 01 Apr 2016

Cited by 12 | Viewed by 8774

Abstract

We report the holographic fabrication of designed defect lines in photonic crystal lattices through phase engineering using a spatial light modulator (SLM). The diffracted beams from the SLM not only carry the defect’s content but also the defect related phase-shifting information. The phase-shifting [...] Read more.

We report the holographic fabrication of designed defect lines in photonic crystal lattices through phase engineering using a spatial light modulator (SLM). The diffracted beams from the SLM not only carry the defect’s content but also the defect related phase-shifting information. The phase-shifting induced lattice shifting in photonic lattices around the defects in three-beam interference is less than the one produced by five-beam interference due to the alternating shifting in lattice in three beam interference. By designing the defect line at a 45 degree orientation and using three-beam interference, the defect orientation can be aligned with the background photonic lattice, and the shifting is only in one side of the defect line, in agreement with the theory. Finally, a new design for the integration of functional defect lines in a background phase pattern reduces the relative phase shift of the defect and utilizes the different diffraction efficiency between the defect line and background phase pattern. We demonstrate that the desired and functional defect lattice can be registered into the background lattice through the direct imaging of designed phase patterns. Full article

(This article belongs to the Special Issue Micro/Nano Photonic Devices and Systems)

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4194 KiB

Open AccessFeature PaperArticle

Resonant Varifocal Micromirror with Piezoresistive Focus Sensor

by Kenta Nakazawa, Takashi Sasaki, Hiromasa Furuta, Jiro Kamiya, Hideki Sasaki, Toshikazu Kamiya and Kazuhiro Hane

Micromachines 2016, 7(4), 57; https://doi.org/10.3390/mi7040057 - 30 Mar 2016

Cited by 10 | Viewed by 5668

Abstract

This paper reports a microelectromechanical systems (MEMS) resonant varifocal mirror integrated with piezoresistive focus sensor. The varifocal mirror is driven electrostatically at a resonant frequency of a mirror plate to obtain the wide scanning range of a focal length. A piezoresistor is used [...] Read more.

This paper reports a microelectromechanical systems (MEMS) resonant varifocal mirror integrated with piezoresistive focus sensor. The varifocal mirror is driven electrostatically at a resonant frequency of a mirror plate to obtain the wide scanning range of a focal length. A piezoresistor is used to monitor the focal length of the varifocal mirror. The device is made of a silicon-on-insulator (SOI) wafer and a glass wafer. A mirror plate and a counter electrode are fabricated by a top silicon layer of the SOI wafer and on the glass wafer, respectively. The piezoresistor is fabricated by ion implantation on a supporting beam of the mirror plate. The stress variation of the beam, which is detected by the piezoresistor, correspond the focal length of the varifocal mirror. The focus length varies from −41 to 35 mm at the resonant frequency of 9.5 kHz. The focal length of the varifocal mirror is monitored by the piezoresistor in real time. Full article

(This article belongs to the Special Issue Micro/Nano Photonic Devices and Systems)

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7556 KiB

Open AccessArticle

Eye Vision Testing System and Eyewear Using Micromachines

by Nabeel A. Riza, M. Junaid Amin and Mehdi N. Riza

Micromachines 2015, 6(11), 1690-1709; https://doi.org/10.3390/mi6111449 - 06 Nov 2015

Cited by 4 | Viewed by 13151

Abstract

Proposed is a novel eye vision testing system based on micromachines that uses micro-optic, micromechanic, and microelectronic technologies. The micromachines include a programmable micro-optic lens and aperture control devices, pico-projectors, Radio Frequency (RF), optical wireless communication and control links, and energy harvesting and [...] Read more.

Proposed is a novel eye vision testing system based on micromachines that uses micro-optic, micromechanic, and microelectronic technologies. The micromachines include a programmable micro-optic lens and aperture control devices, pico-projectors, Radio Frequency (RF), optical wireless communication and control links, and energy harvesting and storage devices with remote wireless energy transfer capabilities. The portable lightweight system can measure eye refractive powers, optimize light conditions for the eye under testing, conduct color-blindness tests, and implement eye strain relief and eye muscle exercises via time sequenced imaging. A basic eye vision test system is built in the laboratory for near-sighted (myopic) vision spherical lens refractive error correction. Refractive error corrections from zero up to −5.0 Diopters and −2.0 Diopters are experimentally demonstrated using the Electronic-Lens (E-Lens) and aperture control methods, respectively. The proposed portable eye vision test system is suited for children’s eye tests and developing world eye centers where technical expertise may be limited. Design of a novel low-cost human vision corrective eyewear is also presented based on the proposed aperture control concept. Given its simplistic and economical design, significant impact can be created for humans with vision problems in the under-developed world. Full article

(This article belongs to the Special Issue Micro/Nano Photonic Devices and Systems)

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Review

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18878 KiB

Open AccessReview

Plasmonic Structures, Materials and Lenses for Optical Lithography beyond the Diffraction Limit: A Review

by Changtao Wang, Wei Zhang, Zeyu Zhao, Yanqin Wang, Ping Gao, Yunfei Luo and Xiangang Luo

Micromachines 2016, 7(7), 118; https://doi.org/10.3390/mi7070118 - 13 Jul 2016

Cited by 45 | Viewed by 11274

Abstract

The rapid development of nanotechnologies and sciences has led to the great demand for novel lithography methods allowing large area, low cost and high resolution nano fabrications. Characterized by unique sub-diffraction optical features like propagation with an ultra-short wavelength and great field enhancement [...] Read more.

The rapid development of nanotechnologies and sciences has led to the great demand for novel lithography methods allowing large area, low cost and high resolution nano fabrications. Characterized by unique sub-diffraction optical features like propagation with an ultra-short wavelength and great field enhancement in subwavelength regions, surface plasmon polaritons (SPPs), including surface plasmon waves, bulk plasmon polaritons (BPPs) and localized surface plasmons (LSPs), have become potentially promising candidates for nano lithography. In this paper, investigations into plasmonic lithography in the manner of point-to-point writing, interference and imaging were reviewed in detail. Theoretical simulations and experiments have demonstrated plasmonic lithography resolution far beyond the conventional diffraction limit, even with ultraviolet light sources and single exposure performances. Half-pitch resolution as high as 22 nm (~1/17 light wavelength) was observed in plasmonic lens imaging lithography. Moreover, not only the overview of state-of-the-art results, but also the physics behind them and future research suggestions are discussed as well. Full article

(This article belongs to the Special Issue Micro/Nano Photonic Devices and Systems)

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6792 KiB

Open AccessReview

Mechanically-Tunable Photonic Devices with On-Chip Integrated MEMS/NEMS Actuators

by Han Du, Fook Siong Chau and Guangya Zhou

Micromachines 2016, 7(4), 69; https://doi.org/10.3390/mi7040069 - 16 Apr 2016

Cited by 35 | Viewed by 11705

Abstract

This article reviews mechanically-tunable photonic devices with on-chip integrated MEMS/NEMS actuators. With related reports mostly published within the last decade, this review focuses on the tuning mechanisms of various passive silicon photonic devices, including tunable waveguides, couplers, ring/disk resonators, and photonic crystal cavities, [...] Read more.

This article reviews mechanically-tunable photonic devices with on-chip integrated MEMS/NEMS actuators. With related reports mostly published within the last decade, this review focuses on the tuning mechanisms of various passive silicon photonic devices, including tunable waveguides, couplers, ring/disk resonators, and photonic crystal cavities, and their results are selectively elaborated upon and compared. Applications of the mechanisms are also discussed. Future development of mechanically-tunable photonics is considered and one possible approach is based on plasmonics, which can confine light energy in the nano-scale space. Optomechanics is another innovation, derived from the strong coupling of optical and mechanical degrees of freedom. State-of-the-art studies of mechanically-tunable plasmonics and on-chip optomechanics are also selectively reviewed. Full article

(This article belongs to the Special Issue Micro/Nano Photonic Devices and Systems)

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