Innovative optical component design

What is the meaning of a sub-lambda diffractive optic?

This is a diffractive optical element (DOE) with 4 or more phase levels with a binary thickness profile. A DOE pixel contains some periods of a diffractive grating with sub-wavelength period. This approach is also called effective medium.

Our work focuses on:

• DOE modeling with effective medium
• adaptaion of laser ablation lithography for sub-wavelength period DOE manufacturing
• manufacturing of DOE with effective medium by photolithography technique
• coupling rigorous electromagnetic calculation tools such as FDTD and RSM
• modeling sub-wavelength period gratings with FMM and FDTD tools.

We have recently obtained:

• the calibration of effective medium DOE fulfilling both splitter and beam combiner functions for applications related to solar energy.

Funding:

• thesis scholarship region Alsace
• Iraqi government thesis grant.

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  Surface thickness modulation of 4-typical-level DOE with an effective medium

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  Black and white image used for the development of the photolithographic mask used to manufacture effective medium cylindrical lens

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  Simulation of an effective medium Fresnel lens

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  False colour height image of a 4-level DOE measured by interferometry (CSI, Zygo)