Abstract

We consider the design of optical systems capable of providing near 100% absorption of visible light, consisting of a structured thin layer of a weakly absorbing semiconductor placed on top of a dielectric spacer layer and a metallic mirror layer. We generalise a system recently studied semi-analytically and experimentally by Stürmberg et al [Optica 3, 556 2016] which incorporated a grating layer of antimony sulphide and delivered high, narrow-band absorptance of normally-incident light for a single polarisation. We demonstrate that bi-periodic gratings can be optimised to deliver near–perfect absorptance of unpolarised light in the system, and comment on the wavelength and angular ranges over which the absorptance remains near 100%. We show that the properties of the systems studied depend on the interaction of multiple modes, and cannot be accurately modelled within the quasistatic approximation.

© 2016 Optical Society of America

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References

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  1. L. M. Hadley and D. M. Dennison, “Reflection and Transmission Interference Filters,” J. Opt. Soc. Amer. 37, 451–465 (1947).
    [Crossref]
  2. L.C. Botten, R. C. McPhedran, N.A. Nicorovici, and G.H. Derrick, “Periodic Models for Thin Optimal Absorbers of Electromagnetic Radiation,” Phys. Rev. B 55, R10672 (1997).
    [Crossref]
  3. C.A. Davis, D. R. McKenzie, and R.C. McKenzie, “Optical Properties and Microstructure of Thin Silver Films,” Opt. Commun. 85, 70–82 (1991).
    [Crossref]
  4. M. C. Hutley and D. Maystre, “The total absorption of light by a diffraction grating,” Opt. Commun. 19, 431–436 (1976).
    [Crossref]
  5. E. Popov, D. Maystre, R.C. McPhedran, M. Nevière, M.C. Hutley, and G.H Derrick, “Total absorption of unpolarised light by crossed gratings,” Opt. Express 16, 6146–6155 (2008).
    [Crossref] [PubMed]
  6. W.W. Salisbury, “Absorbent body for electromagnetic waves,” U.S. Patent 2599944, June 10, 1952.
  7. Y.D. Chong, L. Ge, H. Cao, and A.D. Stone, “Coherent perfect absorbers: Time-reversed lasers,” Phys. Rev. Lett. 105, 1–4 (2010).
    [Crossref]
  8. J. A. Giese, J. W. Yoon, B. R. Wenner, J. W. Allen, M. S. Allen, and R. Magnusson, “Guided-mode resonant coherent light absorbers,” Opt. Lett. 39, 486–488 (2014).
    [Crossref] [PubMed]
  9. A. L. Fannin, J. W. Yoon, B. R. Wenner, J. W. Allen, M. S. Allen, and R. Magnusson, “Experimental Evidence for Coherent Perfect Absorption in Guided-Mode Resonant Silicon Films,” IEEE Photon. J. 8, 6802307 (2016).
    [Crossref]
  10. M.A. Kats, “Ultra-thin perfect absorber employing a tunable phase change material,” Appl. Phys. Lett. 101, 221101 (2012).
    [Crossref]
  11. J.R. Piper and S. Fan, “Total Absorption in a Graphene Monolayer in the Optical Regime by Critical Coupling with a Photonic Crystal Guided Resonance,” ACS Photonics 1, 343–353 (2014).
    [Crossref]
  12. Q-C Zhang and D.R. Mills, “Very-low emittance solar selective surfaces using new film structures,” J. Appl. Phys.72, 3013–3021.
  13. G.H. Derrick, R.C. McPhedran, and D. R. McKenzie, “Theoretical studies of textured amorphous silicon solar cells,” Appl. Opt. 25, 3690–3696 (2012).
    [Crossref]
  14. W.T. Perrins, D.R. McKenzie, and R.C. McPhedran, “Transport Properties of Regular Arrays of Cylinders,” Proc. R. Soc. Lond. A 369, 207–225 (1979).
    [Crossref]
  15. B.C.P. Stürmberg, T.K. Chong, D-Y Choi, T.P. White, L.C. Botten, K.B. Dossou, C. G. Poulton, K.R. Catchpole, R.C. McPhedran, and C. M. de Sterke, “Total absorption of visible light in ultrathin weakly absorbing semiconductor gratings,” Optica 3, 556–562 (2016).
    [Crossref]
  16. B.J. Eggleton, B. Luther-Davies, and K. Richardson, “Chalcogenide photonics,” Nature Photonics 5, 141–148 (2011).
  17. L. Li, “Use of Fourier series in the analysis of discontinuous periodic structures,” J. Opt. Soc. Am. A 13, 1870–1876 (1996)
    [Crossref]
  18. L. Li, “New formulation of the Fourier modal method for crossed surface relief gratings,” J. Opt. Soc. Am. A 14, 2758–2767 (1997).
    [Crossref]
  19. M. Nevière and E. Popov, “Crossed gratings,” in Light Propagation in Periodic Media, Differential Theory and Design (Marcel Dekker, New York, 2003), Chap. 9.

2016 (2)

A. L. Fannin, J. W. Yoon, B. R. Wenner, J. W. Allen, M. S. Allen, and R. Magnusson, “Experimental Evidence for Coherent Perfect Absorption in Guided-Mode Resonant Silicon Films,” IEEE Photon. J. 8, 6802307 (2016).
[Crossref]

B.C.P. Stürmberg, T.K. Chong, D-Y Choi, T.P. White, L.C. Botten, K.B. Dossou, C. G. Poulton, K.R. Catchpole, R.C. McPhedran, and C. M. de Sterke, “Total absorption of visible light in ultrathin weakly absorbing semiconductor gratings,” Optica 3, 556–562 (2016).
[Crossref]

2014 (2)

J. A. Giese, J. W. Yoon, B. R. Wenner, J. W. Allen, M. S. Allen, and R. Magnusson, “Guided-mode resonant coherent light absorbers,” Opt. Lett. 39, 486–488 (2014).
[Crossref] [PubMed]

J.R. Piper and S. Fan, “Total Absorption in a Graphene Monolayer in the Optical Regime by Critical Coupling with a Photonic Crystal Guided Resonance,” ACS Photonics 1, 343–353 (2014).
[Crossref]

2012 (2)

M.A. Kats, “Ultra-thin perfect absorber employing a tunable phase change material,” Appl. Phys. Lett. 101, 221101 (2012).
[Crossref]

G.H. Derrick, R.C. McPhedran, and D. R. McKenzie, “Theoretical studies of textured amorphous silicon solar cells,” Appl. Opt. 25, 3690–3696 (2012).
[Crossref]

2011 (1)

B.J. Eggleton, B. Luther-Davies, and K. Richardson, “Chalcogenide photonics,” Nature Photonics 5, 141–148 (2011).

2010 (1)

Y.D. Chong, L. Ge, H. Cao, and A.D. Stone, “Coherent perfect absorbers: Time-reversed lasers,” Phys. Rev. Lett. 105, 1–4 (2010).
[Crossref]

2008 (1)

1997 (2)

L. Li, “New formulation of the Fourier modal method for crossed surface relief gratings,” J. Opt. Soc. Am. A 14, 2758–2767 (1997).
[Crossref]

L.C. Botten, R. C. McPhedran, N.A. Nicorovici, and G.H. Derrick, “Periodic Models for Thin Optimal Absorbers of Electromagnetic Radiation,” Phys. Rev. B 55, R10672 (1997).
[Crossref]

1996 (1)

1991 (1)

C.A. Davis, D. R. McKenzie, and R.C. McKenzie, “Optical Properties and Microstructure of Thin Silver Films,” Opt. Commun. 85, 70–82 (1991).
[Crossref]

1979 (1)

W.T. Perrins, D.R. McKenzie, and R.C. McPhedran, “Transport Properties of Regular Arrays of Cylinders,” Proc. R. Soc. Lond. A 369, 207–225 (1979).
[Crossref]

1976 (1)

M. C. Hutley and D. Maystre, “The total absorption of light by a diffraction grating,” Opt. Commun. 19, 431–436 (1976).
[Crossref]

1947 (1)

L. M. Hadley and D. M. Dennison, “Reflection and Transmission Interference Filters,” J. Opt. Soc. Amer. 37, 451–465 (1947).
[Crossref]

Allen, J. W.

A. L. Fannin, J. W. Yoon, B. R. Wenner, J. W. Allen, M. S. Allen, and R. Magnusson, “Experimental Evidence for Coherent Perfect Absorption in Guided-Mode Resonant Silicon Films,” IEEE Photon. J. 8, 6802307 (2016).
[Crossref]

J. A. Giese, J. W. Yoon, B. R. Wenner, J. W. Allen, M. S. Allen, and R. Magnusson, “Guided-mode resonant coherent light absorbers,” Opt. Lett. 39, 486–488 (2014).
[Crossref] [PubMed]

Allen, M. S.

A. L. Fannin, J. W. Yoon, B. R. Wenner, J. W. Allen, M. S. Allen, and R. Magnusson, “Experimental Evidence for Coherent Perfect Absorption in Guided-Mode Resonant Silicon Films,” IEEE Photon. J. 8, 6802307 (2016).
[Crossref]

J. A. Giese, J. W. Yoon, B. R. Wenner, J. W. Allen, M. S. Allen, and R. Magnusson, “Guided-mode resonant coherent light absorbers,” Opt. Lett. 39, 486–488 (2014).
[Crossref] [PubMed]

Botten, L.C.

Cao, H.

Y.D. Chong, L. Ge, H. Cao, and A.D. Stone, “Coherent perfect absorbers: Time-reversed lasers,” Phys. Rev. Lett. 105, 1–4 (2010).
[Crossref]

Catchpole, K.R.

Choi, D-Y

Chong, T.K.

Chong, Y.D.

Y.D. Chong, L. Ge, H. Cao, and A.D. Stone, “Coherent perfect absorbers: Time-reversed lasers,” Phys. Rev. Lett. 105, 1–4 (2010).
[Crossref]

Davis, C.A.

C.A. Davis, D. R. McKenzie, and R.C. McKenzie, “Optical Properties and Microstructure of Thin Silver Films,” Opt. Commun. 85, 70–82 (1991).
[Crossref]

de Sterke, C. M.

Dennison, D. M.

L. M. Hadley and D. M. Dennison, “Reflection and Transmission Interference Filters,” J. Opt. Soc. Amer. 37, 451–465 (1947).
[Crossref]

Derrick, G.H

Derrick, G.H.

G.H. Derrick, R.C. McPhedran, and D. R. McKenzie, “Theoretical studies of textured amorphous silicon solar cells,” Appl. Opt. 25, 3690–3696 (2012).
[Crossref]

L.C. Botten, R. C. McPhedran, N.A. Nicorovici, and G.H. Derrick, “Periodic Models for Thin Optimal Absorbers of Electromagnetic Radiation,” Phys. Rev. B 55, R10672 (1997).
[Crossref]

Dossou, K.B.

Eggleton, B.J.

B.J. Eggleton, B. Luther-Davies, and K. Richardson, “Chalcogenide photonics,” Nature Photonics 5, 141–148 (2011).

Fan, S.

J.R. Piper and S. Fan, “Total Absorption in a Graphene Monolayer in the Optical Regime by Critical Coupling with a Photonic Crystal Guided Resonance,” ACS Photonics 1, 343–353 (2014).
[Crossref]

Fannin, A. L.

A. L. Fannin, J. W. Yoon, B. R. Wenner, J. W. Allen, M. S. Allen, and R. Magnusson, “Experimental Evidence for Coherent Perfect Absorption in Guided-Mode Resonant Silicon Films,” IEEE Photon. J. 8, 6802307 (2016).
[Crossref]

Ge, L.

Y.D. Chong, L. Ge, H. Cao, and A.D. Stone, “Coherent perfect absorbers: Time-reversed lasers,” Phys. Rev. Lett. 105, 1–4 (2010).
[Crossref]

Giese, J. A.

Hadley, L. M.

L. M. Hadley and D. M. Dennison, “Reflection and Transmission Interference Filters,” J. Opt. Soc. Amer. 37, 451–465 (1947).
[Crossref]

Hutley, M. C.

M. C. Hutley and D. Maystre, “The total absorption of light by a diffraction grating,” Opt. Commun. 19, 431–436 (1976).
[Crossref]

Hutley, M.C.

Kats, M.A.

M.A. Kats, “Ultra-thin perfect absorber employing a tunable phase change material,” Appl. Phys. Lett. 101, 221101 (2012).
[Crossref]

Li, L.

Luther-Davies, B.

B.J. Eggleton, B. Luther-Davies, and K. Richardson, “Chalcogenide photonics,” Nature Photonics 5, 141–148 (2011).

Magnusson, R.

A. L. Fannin, J. W. Yoon, B. R. Wenner, J. W. Allen, M. S. Allen, and R. Magnusson, “Experimental Evidence for Coherent Perfect Absorption in Guided-Mode Resonant Silicon Films,” IEEE Photon. J. 8, 6802307 (2016).
[Crossref]

J. A. Giese, J. W. Yoon, B. R. Wenner, J. W. Allen, M. S. Allen, and R. Magnusson, “Guided-mode resonant coherent light absorbers,” Opt. Lett. 39, 486–488 (2014).
[Crossref] [PubMed]

Maystre, D.

McKenzie, D. R.

G.H. Derrick, R.C. McPhedran, and D. R. McKenzie, “Theoretical studies of textured amorphous silicon solar cells,” Appl. Opt. 25, 3690–3696 (2012).
[Crossref]

C.A. Davis, D. R. McKenzie, and R.C. McKenzie, “Optical Properties and Microstructure of Thin Silver Films,” Opt. Commun. 85, 70–82 (1991).
[Crossref]

McKenzie, D.R.

W.T. Perrins, D.R. McKenzie, and R.C. McPhedran, “Transport Properties of Regular Arrays of Cylinders,” Proc. R. Soc. Lond. A 369, 207–225 (1979).
[Crossref]

McKenzie, R.C.

C.A. Davis, D. R. McKenzie, and R.C. McKenzie, “Optical Properties and Microstructure of Thin Silver Films,” Opt. Commun. 85, 70–82 (1991).
[Crossref]

McPhedran, R. C.

L.C. Botten, R. C. McPhedran, N.A. Nicorovici, and G.H. Derrick, “Periodic Models for Thin Optimal Absorbers of Electromagnetic Radiation,” Phys. Rev. B 55, R10672 (1997).
[Crossref]

McPhedran, R.C.

Mills, D.R.

Q-C Zhang and D.R. Mills, “Very-low emittance solar selective surfaces using new film structures,” J. Appl. Phys.72, 3013–3021.

Nevière, M.

E. Popov, D. Maystre, R.C. McPhedran, M. Nevière, M.C. Hutley, and G.H Derrick, “Total absorption of unpolarised light by crossed gratings,” Opt. Express 16, 6146–6155 (2008).
[Crossref] [PubMed]

M. Nevière and E. Popov, “Crossed gratings,” in Light Propagation in Periodic Media, Differential Theory and Design (Marcel Dekker, New York, 2003), Chap. 9.

Nicorovici, N.A.

L.C. Botten, R. C. McPhedran, N.A. Nicorovici, and G.H. Derrick, “Periodic Models for Thin Optimal Absorbers of Electromagnetic Radiation,” Phys. Rev. B 55, R10672 (1997).
[Crossref]

Perrins, W.T.

W.T. Perrins, D.R. McKenzie, and R.C. McPhedran, “Transport Properties of Regular Arrays of Cylinders,” Proc. R. Soc. Lond. A 369, 207–225 (1979).
[Crossref]

Piper, J.R.

J.R. Piper and S. Fan, “Total Absorption in a Graphene Monolayer in the Optical Regime by Critical Coupling with a Photonic Crystal Guided Resonance,” ACS Photonics 1, 343–353 (2014).
[Crossref]

Popov, E.

E. Popov, D. Maystre, R.C. McPhedran, M. Nevière, M.C. Hutley, and G.H Derrick, “Total absorption of unpolarised light by crossed gratings,” Opt. Express 16, 6146–6155 (2008).
[Crossref] [PubMed]

M. Nevière and E. Popov, “Crossed gratings,” in Light Propagation in Periodic Media, Differential Theory and Design (Marcel Dekker, New York, 2003), Chap. 9.

Poulton, C. G.

Richardson, K.

B.J. Eggleton, B. Luther-Davies, and K. Richardson, “Chalcogenide photonics,” Nature Photonics 5, 141–148 (2011).

Salisbury, W.W.

W.W. Salisbury, “Absorbent body for electromagnetic waves,” U.S. Patent 2599944, June 10, 1952.

Stone, A.D.

Y.D. Chong, L. Ge, H. Cao, and A.D. Stone, “Coherent perfect absorbers: Time-reversed lasers,” Phys. Rev. Lett. 105, 1–4 (2010).
[Crossref]

Stürmberg, B.C.P.

Wenner, B. R.

A. L. Fannin, J. W. Yoon, B. R. Wenner, J. W. Allen, M. S. Allen, and R. Magnusson, “Experimental Evidence for Coherent Perfect Absorption in Guided-Mode Resonant Silicon Films,” IEEE Photon. J. 8, 6802307 (2016).
[Crossref]

J. A. Giese, J. W. Yoon, B. R. Wenner, J. W. Allen, M. S. Allen, and R. Magnusson, “Guided-mode resonant coherent light absorbers,” Opt. Lett. 39, 486–488 (2014).
[Crossref] [PubMed]

White, T.P.

Yoon, J. W.

A. L. Fannin, J. W. Yoon, B. R. Wenner, J. W. Allen, M. S. Allen, and R. Magnusson, “Experimental Evidence for Coherent Perfect Absorption in Guided-Mode Resonant Silicon Films,” IEEE Photon. J. 8, 6802307 (2016).
[Crossref]

J. A. Giese, J. W. Yoon, B. R. Wenner, J. W. Allen, M. S. Allen, and R. Magnusson, “Guided-mode resonant coherent light absorbers,” Opt. Lett. 39, 486–488 (2014).
[Crossref] [PubMed]

Zhang, Q-C

Q-C Zhang and D.R. Mills, “Very-low emittance solar selective surfaces using new film structures,” J. Appl. Phys.72, 3013–3021.

ACS Photonics (1)

J.R. Piper and S. Fan, “Total Absorption in a Graphene Monolayer in the Optical Regime by Critical Coupling with a Photonic Crystal Guided Resonance,” ACS Photonics 1, 343–353 (2014).
[Crossref]

Appl. Opt. (1)

Appl. Phys. Lett. (1)

M.A. Kats, “Ultra-thin perfect absorber employing a tunable phase change material,” Appl. Phys. Lett. 101, 221101 (2012).
[Crossref]

IEEE Photon. J. (1)

A. L. Fannin, J. W. Yoon, B. R. Wenner, J. W. Allen, M. S. Allen, and R. Magnusson, “Experimental Evidence for Coherent Perfect Absorption in Guided-Mode Resonant Silicon Films,” IEEE Photon. J. 8, 6802307 (2016).
[Crossref]

J. Opt. Soc. Am. A (2)

J. Opt. Soc. Amer. (1)

L. M. Hadley and D. M. Dennison, “Reflection and Transmission Interference Filters,” J. Opt. Soc. Amer. 37, 451–465 (1947).
[Crossref]

Nature Photonics (1)

B.J. Eggleton, B. Luther-Davies, and K. Richardson, “Chalcogenide photonics,” Nature Photonics 5, 141–148 (2011).

Opt. Commun. (2)

C.A. Davis, D. R. McKenzie, and R.C. McKenzie, “Optical Properties and Microstructure of Thin Silver Films,” Opt. Commun. 85, 70–82 (1991).
[Crossref]

M. C. Hutley and D. Maystre, “The total absorption of light by a diffraction grating,” Opt. Commun. 19, 431–436 (1976).
[Crossref]

Opt. Express (1)

Opt. Lett. (1)

Optica (1)

Phys. Rev. B (1)

L.C. Botten, R. C. McPhedran, N.A. Nicorovici, and G.H. Derrick, “Periodic Models for Thin Optimal Absorbers of Electromagnetic Radiation,” Phys. Rev. B 55, R10672 (1997).
[Crossref]

Phys. Rev. Lett. (1)

Y.D. Chong, L. Ge, H. Cao, and A.D. Stone, “Coherent perfect absorbers: Time-reversed lasers,” Phys. Rev. Lett. 105, 1–4 (2010).
[Crossref]

Proc. R. Soc. Lond. A (1)

W.T. Perrins, D.R. McKenzie, and R.C. McPhedran, “Transport Properties of Regular Arrays of Cylinders,” Proc. R. Soc. Lond. A 369, 207–225 (1979).
[Crossref]

Other (3)

M. Nevière and E. Popov, “Crossed gratings,” in Light Propagation in Periodic Media, Differential Theory and Design (Marcel Dekker, New York, 2003), Chap. 9.

Q-C Zhang and D.R. Mills, “Very-low emittance solar selective surfaces using new film structures,” J. Appl. Phys.72, 3013–3021.

W.W. Salisbury, “Absorbent body for electromagnetic waves,” U.S. Patent 2599944, June 10, 1952.

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Figures (15)

Fig. 1
Fig. 1

Schematic representation of the system consisting of a silver substrate, homogeneous layer of SiO2 with thickness t, and a grating with two-dimensional periodicity (period D in both x and y-directions) and height H which is made of a matrix substance 1 and cylindrical holes made of material 2 (specified in Table 1). The incident direction is specified by two angles, the polar angle ϕ between the incident wavevector and the normal to the surface (z-axis), and the azimuthal angle ψ between the projection k i of ki on the xy-plane. The polarization of the incident wave is kept perpendicular to the xz-plane..

Fig. 2
Fig. 2

(Left) Reflectance (black, left scale) and absorptance (red, right scale) in the silver layer of the grating structure of Case 1, Table 1, as a function of wavelength. Full lines - exact values, dots - taking into account the single order (0, 0) inside the SiO2 homogeneous layer. (Right) Reflectance at the wavelength of minimum normal reflectance as a function of dimensionless direction cosines α and β. The electric field of the incident plane wave is along the β axis.

Fig. 3
Fig. 3

(Left) Reflectance of the grating structure of Case 7, Table 1, as a function of wavelength: black line, taking into account all diffraction orders in SiO2, blue curve, only the propagating orders (0,0), red line, orders (0,0), (0,±1), and (±1,0), black dots, adding also orders (±1,±1). (Right) Flux into the silver substrate as a function of wavelength. Below: Reflectance curve (black) compared with the results of homogenisation (red curve).

Fig. 4
Fig. 4

(Left) Reflectance for the structure of Case 7, Table 1 at a wavelength (0.540 μm) near the first minimum of normal reflectance as a function of dimensionless direction cosines α and β. (Right) As at left, but for the second minimum wavelength (0.591 μm) of normal reflectance.

Fig. 5
Fig. 5

Scattered field components just above the surface of the biperioidc grating, as a function of position (x, y), for the first minimum wavelength (0.5557 μm) of total reflectance. The black dotted lines represent the cylinders made of antimony sulfide.

Fig. 6
Fig. 6

As for Fig. 5, but for the second minimum wavelength (0.591 μm) of normal reflectance. The incident electric field is along the β axis.

Fig. 7
Fig. 7

Total electric field components with respect to z (in μm), in the direction perpendicular to the layers, for x = y = 0. (Left) First minimum wavelength (0.5557 μm) of total reflectance. (Right) Second minimum wavelength (0.591 μm) of total reflectance. The black dotted lines represent the layers interfaces from the substrate (bottom) to the superstrate (top).

Fig. 8
Fig. 8

(Left) Reflectance (black) and absorptance (red) in the silver layer of the grating structure of Case 2, Table 1, as a function of wavelength. (Right) Reflectance at the wavelength of minimum normal reflectance as a function of dimensionless direction cosines α and β.

Fig. 9
Fig. 9

(Left) Reflectance (black) and absorptance (red) in the silver layer of the grating structure of Case 3, Table 1, as a function of wavelength. (Right) Reflectance at the wavelength of minimum normal reflectance as a function of dimensionless direction cosines α and β.

Fig. 10
Fig. 10

(Left) Reflectance (black) and absorptance (red) in the silver layer of the grating structure of Case 4, Table 1, as a function of wavelength. (Right) Reflectance at the wavelength of minimum normal reflectance as a function of dimensionless direction cosines α and β.

Fig. 11
Fig. 11

(Left) Reflectance (black) and absorptance (red) in the silver layer of the grating structure of Case 5, Table 1, as a function of wavelength. (Right) Reflectance at the wavelength of minimum normal reflectance as a function of dimensionless direction cosines α and β.

Fig. 12
Fig. 12

(Left) Reflectance (black) and absorptance (red) in the silver layer of the grating structure of Case 6, Table 1, as a function of wavelength. (Right) Reflectance at the wavelength of minimum normal reflectance as a function of dimensionless direction cosines α and β.

Fig. 13
Fig. 13

(Left) Reflectance (black) and absorptance (red) in the silver layer of the grating structure of Case 8, Table 1, as a function of wavelength. (Right) Reflectance at the wavelength of minimum normal reflectance as a function of dimensionless direction cosines α and β.

Fig. 14
Fig. 14

(Left) Reflectance (black) and absorptance (red) in the silver layer of the grating structure of Case 9, Table 1, as a function of wavelength. (Right) Reflectance at the wavelength of minimum normal reflectance as a function of dimensionless direction cosines α and β.

Fig. 15
Fig. 15

(Left) Reflectance (black) and absorptance (red) in the silver layer of the grating structure of Case 10, Table 1, as a function of wavelength. (Right) Reflectance at the wavelength of minimum normal reflectance as a function of dimensionless direction cosines α and β.

Tables (1)

Tables Icon

Table 1 The parameters of the 10 optimised doubly-periodic absorber systems: lattice type, constituents (1 for the matrix, 2 for the inclusion), spacer thickness, cylinder diameter, cylinder length, reflectance at the design wavelength and flux into the silver substrate. Distances in μm.

Metrics