Characterization of planar microlenses made of high contrast gratings

Klemm, Annett B.; Stellinga, Daan; Martins, Emiliano R.; Lewis, Liam; О’Faolain, L.; Krauss, Thomas F.

doi:10.1117/12.2045726

Cited by 3 publications

(4 citation statements)

References 5 publications

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“…While conceptually promising, there are several challenges in the existing optical concentration technologies such as precise tracking, maintenance requirements, lower lifetime of opto-mechanical moving components, absence of spectrally selective light guiding, etc. Grating based designs are one of the approaches to realize a planar concentrator to overcome most of these challenges 29–31 . There a various High Contrast Grating (HCG) based designs such as aperiodic metasurfaces as a planar focusing element 32 , a two-dimensional metasurface as planar micro-lenses 30 and a metal-based Fabry-Perot cavity solar cell 33 .…”

Section: Introductionmentioning

confidence: 99%

“…For incident radiation with Transverse Electric (TE) polarization, the electric field is parallel to the grating bars while for Transverse Magnetic (TM) polarization, the magnetic field is parallel to the grating bars. Optimization enables the incident light of desired wavelengths to be diffracted into single transmission order 29 , thus effectively guiding the light to the window edges.…”

Section: Introductionmentioning

confidence: 99%

“…While conceptually promising, there are a variety of challenges in existing optical concentration technologies. Grating based designs are one approach to realize a planar concentrator overcoming most of these challenges [28][29][30] 33 . Here, we explore subwavelength metasurface, or grating based, planar concentrator in this work.…”

Section: Introductionmentioning

confidence: 99%

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A Spectrally Tunable Dielectric Subwavelength Grating based Broadband Planar Light Concentrator

Elikkottil

Tahersima

Gupta

et al. 2019

Sci Rep

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Energy consumption of buildings is increasing at a rapid pace due to urbanization, while net-zero energy buildings offer a green and sustainable solution. However, limited rooftop availability on multi-story buildings poses a challenge for large-scale integration of photovoltaics. Conventional silicon solar panels block visible light making them unfeasible to cover all the surfaces of a building. Here, we demonstrate a novel dielectric grating based planar light concentrator. We integrate this functional device onto a window glass transmitting visible light while simultaneously guiding near infrared (NIR) portion of sunlight to edges of the glass window where it is converted to electricity by a photovoltaic cell. Gratings are designed to guide NIR region and realize polarization independent performance. Experimentally, we observe 0.72% optical guiding efficiency in the NIR region (700–1000 nm), transmitting majority of the visible portion for natural room lighting. Integrating solar cell at the window edge, we find an electrical conversion efficiency of about 0.65% of NIR light with a 25 mm 2 prototype. Major losses are coupling and guiding losses arising from non-uniformity in fabrication over a large area. Such a functional window combining energy generation, natural room lighting and heat load reduction could mitigate urban heat island effect in modern cities.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A Spectrally Tunable Dielectric Subwavelength Grating based Broadband Planar Light Concentrator

Elikkottil

Tahersima

Gupta

et al. 2019

Sci Rep

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“…17 Our sincere thanks go to Professor Kishan Dholakia, University of St. Andrews, for providing us with the 1064-nm fiber laser used in Fig. 5.…”

Section: Acknowledgmentsmentioning

confidence: 99%

Focusing with planar microlenses made of two-dimensionally varying high contrast gratings

et al. 2014

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Abstract. We report on the focusing performance of reflective two-dimensionally varying high contrast grating lenses based on silicon. The combination of their subwavelength nature and their high refractive index contrast makes it possible to create highly tolerant and planar microlenses. We used a rigorous mathematical code to design the lenses and verified their performance with finite element simulations. We also investigated the effects of grating thickness, angle, and wavelength of incidence in these simulations. Experimentally, we show the evolution of the beam profile along the optical axis for a lens with a high (0.37) numerical aperture. We have explored a wide range of numerical apertures (0.1-0.93) and show that the lenses behave as expected across the full range. Our analyses demonstrate the large design flexibility with which these lenses can be made along with ease of fabrication and potential for a number of applications in micro-optics.

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Optical trapping with planar silicon metalenses

et al. 2018

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Contactless manipulation of micron-scale objects in a microfluidic environment is a key ingredient for a range of applications in the biosciences, including sorting, guiding, and analysis of cells and bacteria. Optical forces are powerful for this purpose but, typically, require bulky focusing elements to achieve the appropriate optical field gradients. To this end, realizing the focusing optics in a planar format would be very attractive and conducive to the integration of such microscale devices, either individually or as arrays. Here we report on, to the best of our knowledge, the first experimental demonstration of optical trapping using planar silicon metalenses illuminated with a collimated laser beam. The structures consist of high-contrast gratings with a locally varying period and duty cycle. They are designed to mimic parabolic reflectors with a numerical aperture of 0.56 at a vacuum wavelength of 1064 nm. We achieve both two- and three-dimensional trapping in water, with the latter realized by omitting the central Fresnel zones. This Letter highlights the versatility of such lithographically defined metastructures for exerting optical forces without the need for traditional optical elements.

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Characterization of planar microlenses made of high contrast gratings

Cited by 3 publications

References 5 publications

A Spectrally Tunable Dielectric Subwavelength Grating based Broadband Planar Light Concentrator

A Spectrally Tunable Dielectric Subwavelength Grating based Broadband Planar Light Concentrator

Focusing with planar microlenses made of two-dimensionally varying high contrast gratings

Optical trapping with planar silicon metalenses

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