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| Format: | Preprint |
| Publié: |
2024
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| Accès en ligne: | https://arxiv.org/abs/2407.19559 |
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| _version_ | 1866911970956935168 |
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| author | Collin, Stéphane Giteau, Maxime |
| author_facet | Collin, Stéphane Giteau, Maxime |
| contents | We address the question of the optimal broadband absorption of waves in an open, dissipative system. We develop a general framework for absorption induced by multiple overlapping resonances, based on quasi-normal modes and radiative and non-radiative decay rates. Upper bounds on broadband absorption in a slab of thickness $d$ take the simple form: $A= 1-\exp(-F αd)$, where $α$ is the absorption coefficient and $F$ the path enhancement factor. We apply these results to sunlight absorption in photovoltaics and answer the long-standing debate on the best light-trapping strategy in solar cells. For angle-independent absorption, we derive the isotropic scattering upper bound $F = 4 n^2$ ($n$ the refractive index), extending the well-know Yablonovitch limit beyond the ray optics and weak absorption regimes. For angle-restricted illumination, we show that $F$ can be further increased up to $8 πn^2 / \sqrt{3}$ using multi-resonant absorption induced by periodical patterning. These results have a general scope in the field of wave physics and open new opportunities to maximize absorption, detection, and attenuation of electromagnetic or mechanical waves in ultrathin devices. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2407_19559 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Upper bounds on broadband absorption Collin, Stéphane Giteau, Maxime Optics Materials Science Applied Physics We address the question of the optimal broadband absorption of waves in an open, dissipative system. We develop a general framework for absorption induced by multiple overlapping resonances, based on quasi-normal modes and radiative and non-radiative decay rates. Upper bounds on broadband absorption in a slab of thickness $d$ take the simple form: $A= 1-\exp(-F αd)$, where $α$ is the absorption coefficient and $F$ the path enhancement factor. We apply these results to sunlight absorption in photovoltaics and answer the long-standing debate on the best light-trapping strategy in solar cells. For angle-independent absorption, we derive the isotropic scattering upper bound $F = 4 n^2$ ($n$ the refractive index), extending the well-know Yablonovitch limit beyond the ray optics and weak absorption regimes. For angle-restricted illumination, we show that $F$ can be further increased up to $8 πn^2 / \sqrt{3}$ using multi-resonant absorption induced by periodical patterning. These results have a general scope in the field of wave physics and open new opportunities to maximize absorption, detection, and attenuation of electromagnetic or mechanical waves in ultrathin devices. |
| title | Upper bounds on broadband absorption |
| topic | Optics Materials Science Applied Physics |
| url | https://arxiv.org/abs/2407.19559 |