Performance of solar concentrator made of an achromatic Fresnel doublet measured with a continuous solar simulator and comparison with a singlet

in Solar Energy Materials & Solar Cells (2013), 190

Experimental Results of Flat Fresnel Doublets made of PMMA and PC

Conference (2012, April)

To reduce the chromatic aberration lots of imaging systems like cameras and telescopes turn to achromatic doublets. On the other hand, to be cheaper, lighter and thinner, more and more systems like ... [more ▼]

To reduce the chromatic aberration lots of imaging systems like cameras and telescopes turn to achromatic doublets. On the other hand, to be cheaper, lighter and thinner, more and more systems like projectors and headlights use Fresnel lenses. To combine high performances and low cost, the use achromatic Fresnel doublets has been investigated. [less ▲]

Integrated prism-free coupled surface plasmon resonance biochemical sensor

in Nanophotonics - Proceedings of SPIE Volume 8424 (2012)

Flat Fresnel doublets made of PMMA and PC: combining low cost production and very high concentration ratio for CPV

in Optics Express (2011), 19(S3), 280-294

The linear chromatic aberration (LCA) of several combinations of polycarbonates (PCs) and poly (methyl methacrylates) (PMMAs) as singlet, hybrid (refractive/diffractive) lenses and doublets operating with ... [more ▼]

The linear chromatic aberration (LCA) of several combinations of polycarbonates (PCs) and poly (methyl methacrylates) (PMMAs) as singlet, hybrid (refractive/diffractive) lenses and doublets operating with wavelengths between 380 and 1600 nm – corresponding to a typical zone of interest of concentrated photovoltaics (CPV) – are compared. Those comparisons show that the maximum theoretical concentration factor for singlets is limited to about 1000 × at normal incidence and that hybrid lenses and refractive doublets present a smaller LCA increasing the concentration factor up to 5000 × and 2 × 106 respectively. A new achromatization equation more useful than the Abbé equation is also presented. Finally we determined the ideal position of the focal point as a function of the LCA and the geometric concentration which maximizes the flux on the solar cell. [less ▲]

First manufactured diamond AGPM vector vortex for the L- and N-bands: metrology and expected performances

Conference (2010, October 28)

The AGPM (Annular Groove Phase Mask, Mawet et al. 2005) is an optical vectorial vortex coronagraph (or vector vortex) synthesized by a circular subwavelength grating, that is a grating with a period ... [more ▼]

The AGPM (Annular Groove Phase Mask, Mawet et al. 2005) is an optical vectorial vortex coronagraph (or vector vortex) synthesized by a circular subwavelength grating, that is a grating with a period smaller than λ/n (λ being the observed wavelength and n the refractive index of the grating substrate). Since it is a phase mask, it allows to reach a high contrast with a small working angle. Moreover, its subwavelength structure provides a good achromatization over wide spectral bands. Recently, we have manufactured and measured our first N-band prototypes that allowed us to validate the reproducibility of the microfabrication process. Here, we present newly produced mid-IR diamond AGPMs in the N-band (~10 µm), and in the most wanted L-band (~3.5 µm). We first give an extrapolation of the expected coronagraph performances. We then present the manufacturing and measurement results, using diamond-optimized microfabrication techniques such as nano-imprint lithography (NIL) and reactive ion etching (RIE). Finally, the subwavelength grating profile metrology combines surface metrology (scanning electron microscopy, atomic force microscopy, white light interferometry) with diffractometry on an optical polarimetric bench and cross correlation with theoretical simulations using rigorous coupled wave analysis (RCWA). [less ▲]

Annular groove phase mask coronagraph in diamond for mid-IR wavelengths: manufacturing assessment and performance analysis

in Oschmann, J.; Clampin, M.; MacEwen, H. (Eds.) Space Telescopes and Instrumentation 2010: Optical, Infrared, and Millimeter Wave (2010, July 01)

Phase-mask coronagraphs are known to provide high contrast imaging capabilities while preserving a small inner working angle, which allows searching for exoplanets or circumstellar disks with smaller ... [more ▼]

Phase-mask coronagraphs are known to provide high contrast imaging capabilities while preserving a small inner working angle, which allows searching for exoplanets or circumstellar disks with smaller telescopes or at longer wavelengths. The AGPM (Annular Groove Phase Mask, Mawet et al. 2005[SUP]1[/SUP]) is an optical vectorial vortex coronagraph (or vector vortex) induced by a rotationally symmetric subwavelength grating (i.e. with a period smaller than λ/n, λ being the observed wavelength and n the refractive index of the grating substrate). In this paper, we present our first midinfrared AGPM prototypes imprinted on a diamond substrate. We firstly give an extrapolation of the expected coronagraph performances in the N-band (~10 μm), and prospects for down-scaling the technology to the most wanted L-band (~3.5 μm). We then present the manufacturing and measurement results, using diamond-optimized microfabrication techniques such as nano-imprint lithography (NIL) and reactive ion etching (RIE). Finally, the subwavelength grating profile metrology combines surface metrology (scanning electron microscopy, atomic force microscopy, white light interferometry) with diffractometry on an optical polarimetric bench and cross correlation with theoretical simulations using rigorous coupled wave analysis (RCWA). [less ▲]

Achromatization of solar concentrator using diffractive optics

Poster (2009)

Photovoltaic energy suffers from payback time. High solar concentration (above 500 suns) is a very interesting way to reduce production cost. The use of lenses allows more flexibility to make light flux ... [more ▼]

Photovoltaic energy suffers from payback time. High solar concentration (above 500 suns) is a very interesting way to reduce production cost. The use of lenses allows more flexibility to make light flux more uniform. In addition lenses are less prone to errors of manufacture and can be easily duplicated. Unfortunately, optical materials are very dependent on the wavelength which causes important chromatic aberrations. One can think about achromatic doublets but doublets are thick, heavy and require exotic glasses which make them expensive. During the conference, I would like to present an innovative way to achromatize solar concentrators using hybrid (refractive/diffractive) lenses. Indeed, an hybrid lens is as thin as a Fresnel lens and is made in only one glass. But diffractive lenses suffer from limited broadband diffraction efficiency due to spurious orders. To overcome the lake of efficiency we are investigating the use of multi-layer diffractive optical element. This technique allows to achieve an efficiency greater than 97% over the full visible spectrum using only three components (e.g. two optical elements + air). [less ▲]

Antireflective subwavelength patterning of IR optics

in Proceedings of SPIE (2006), 6395

Thermal infrared (IR) lenses require efficient anti-reflection coating. Moth-eye (or egg-box) 2D subwavelength gratings have demonstrated their ability to reach a very high transmission for a wide ... [more ▼]

Thermal infrared (IR) lenses require efficient anti-reflection coating. Moth-eye (or egg-box) 2D subwavelength gratings have demonstrated their ability to reach a very high transmission for a wide wavelength and angular range. The use in thermal IR is simplified by the lower resolution for lithographic technology, compared to visible waveband. However, deeper structures must be engraved and lithography must be adapted to IR materials. In order to be cost-effective, the patterning must be produced by replication techniques, such as embossing. Our laboratory is now experimenting hot embossing of moth-eye patterns in chalcogenide substrates. In this paper, theoretical analysis, micro-lithographic technology and manufacturing processes are detailed. [less ▲]

Use of subwavelength gratings in TIR incidence as achromatic phase shifters

in Optics Express (2005), 13(22), 8686-8692

Nulling interferometry constitutes a very promising technique in observational astrophysics. This method consists in attenuating the signal of a bright astrophysical object in order to detect much fainter ... [more ▼]

Nulling interferometry constitutes a very promising technique in observational astrophysics. This method consists in attenuating the signal of a bright astrophysical object in order to detect much fainter nearby features, e.g. exoplanets around their host star. An on-axis destructive interference is created by adjusting the phases of the beams coming from various telescopes. The huge flux ratio between the parent star and the planet (106 in the thermal infrared) requires unprecedented high performance broadband phase shifters. We present a new design for these key components called Achromatic Phase Shifters (APS). We propose to use subwavelength diffractive optical elements under total internal reflection (TIR) incidence. Our component can be seen as an evolution of the Fresnel Rhomb technology. [less ▲]

Narrow band-width wavelength filter by guided mode resonance

in Optical Engineering : The Journal of the Society of Photo-Optical Instrumentation Engineers (2004), 43(11), 2631-2639

Simple resonant structures that permit holographic reflection filtering are studied. The filters under study work under a 45-deg incidence for a wavelength of λ=632.8 nm, a condition useful for future ... [more ▼]

Simple resonant structures that permit holographic reflection filtering are studied. The filters under study work under a 45-deg incidence for a wavelength of λ=632.8 nm, a condition useful for future inclusion in substrate mode systems. First, the influence of the structural parameters of the grating and the waveguide on the position and the shape of the resonance peaks are studied by numerical computation. The numerical results, obtained within the rigorous coupled wave theory, are compared with the measured response of some filters. These filters contain a grating recorded by holography deposited on the substrate. In the case of the bilayer filter, a waveguide is introduced between the grating and the substrate. Second, the numerical results are used for the conception of an active substrate mode spectral filter built from electro-optic zinc oxide. [less ▲]