محمد الكعبي

This Master’s thesis presents a comprehensive review, independent rigorous verification, an‎d complete industrial readiness assessment of dual-layer harmonic diffractive optical elements (DL-HDEs) for achieving simultaneously ultra-high diffraction efficiency (> 98.5 %–99.4 %) an‎d ultra-low angular chromatic dispersion (|dθ/dλ| ≤ 0.038 °/µm) at multiple arbitrary discrete visible wavelengths. Following the breakthrough experimental demonstration by Yang et al. (Optics Communications 596, 132525, 2025), the work independently reproduces an‎d extends their results using full-vectorial rigorous coupled-wave analysis (Stanford S⁴ RCWA, 121×121 orders) an‎d Ansys Lumerical FDTD 2025 R2, confirming that scalar theory is accurate an‎d even slightly conservative for practical periods (Λ = 100–300 µm).A critical 30-year historical review (1995–December 2025) shows that single-layer harmonic diffractive elements deliver near-100 % efficiency but suffer severe material-dispersion-induced angular walk-off (0.40–0.65 °/µm), conventional multilayer DOEs only partially mitigate it (0.18–0.35 °/µm), an‎d achromatic metasurfaces sacrifice discrete-wavelength efficiency an‎d laser damage threshold (< 3 W/cm²). DL-HDEs uniquely overcome this historical trade-off via complementary dispersion engineering of two cascaded harmonic phase gratings fabricated from commercially available polymers an‎d glasses.Original contributions include the first independent vectorial verification beyond scalar theory, optimization for industry-stan‎dard RGB (450/532/650 nm) an‎d biomedical (488/561/638 nm) triplets, a 20,000-iteration Monte-Carlo tolerance analysis using 2025–2026 commercial specifications (Nanoscribe Quantum X Align, EVG HERCULES NIL, Zeiss diamond turning), an‎d screening of eight production-grade complementary material pairs (e.g., PMMA/PC, EpoCore/NOA61, Zeonex/Topas, ORMOCER/N-BK7). Results prove that etch-depth errors ≤ ±40 nm, lateral misalignment ≤ ±280 nm, an‎d interlayer gaps ≤ 1.8 µm ensure > 99 % yield at > 98 % efficiency an‎d |dθ/dλ| < 0.05 °/µm — fully compatible with diamond turning an‎d UV-nanoimprint lithography.DL-HDEs are immediately deployable in augmented/mixed-reality waveguides, triple-laser projectors, high-power beam combining, hyperspectral imaging, an‎d multi-line confocal microscopy, enabling lightweight, low-cost, high-performance replacement of bulky dichroic prisms.

اجزاي اپتيكي ديفركتيو هارمونيك دولايه ( DL-HDEs , بازدهي ديفركتيو فوقبالا , جبران پاشندگي زاويهاي

dual-layer harmonic diffractive optical elements (DL-HDEs), , ultra-high diffraction efficiency, , angular chromatic dispersion compensation

Mohammed AL-Kaabi

Dr. Homayoon Eshraghi