Abstract

Radial diffractive gratings are used to couple light of a white LED into a light guide. Theoretical coupling efficiencies are evaluated with rigorous diffraction theory in a pure conical mounting. It is shown that when the refractive index of the grating increases from 1.46 to 2.05 the incoupling efficiency increases from 42%  to  63%. Also, with the increasing refractive index the incoupling efficiency is shown to become more nearly uniform over the visible spectrum. Experimental results for the incoupled efficiencies and the color coordinates of the incoupled spectra are introduced for refractive indices n=1.46 and n=1.56.

© 2006 Optical Society of America

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    [CrossRef]
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2005

2004

2003

D. -E. Yi, Y. -B. Yan, H. -T. Liu, Si -Lu, and G. -F. Jin, " Broadband achromatic phase retarder by subwavelength grating," Opt. Commun. 227, 49- 55 ( 2003).
[CrossRef]

2002

G. Harbers, W. Timmers, and W. Sillevis-Smitt, " LED backlighting for LCD HDTV," J. Soc. Inf. Disp. 10, 347- 350 ( 2002).
[CrossRef]

1999

1997

1943

Brown, J. D.

J. D. Brown, A. Mehta, and H. Hockel, " Improved fabrication accuracy of Bragg gratings," in Micromachining Technology for Micro-Optics and Nano-Optics, E. G. Johnson, G. P. Nordin, and T. J. Suleski, eds., Proc. SPIE 5720, 139- 147 ( 2005).

Cambril, E.

Chavel, P.

de Beaucoudrey, N.

Deguzman, P. C.

Flaim, T.

Y. Wang, T. Flaim, R. Mercado, S. Fowler, D. Holmes, and C. Planje, " Hybrid high refractive index polymer coatings," in Organic Photonic Materials and Devices VII, J. G. Grote, T. Kaino, and F. Kajzar, eds., Proc SPIE 5724, 42- 49 ( 2005).

Folkerts, W.

W. Folkerts, " LED backlighting concepts with hight flux LEDs," SID Symp. Digest 35, 1226- 1229 ( 2004).
[CrossRef]

Fowler, S.

Y. Wang, T. Flaim, R. Mercado, S. Fowler, D. Holmes, and C. Planje, " Hybrid high refractive index polymer coatings," in Organic Photonic Materials and Devices VII, J. G. Grote, T. Kaino, and F. Kajzar, eds., Proc SPIE 5724, 42- 49 ( 2005).

Gale, M. T.

M. T. Gale, J. Pedersen, and H. Schutz, " Active alignment of replicated microlens arrays on a charge-coupled device imager," Opt. Eng. 36, 151015 ( 1997).
[CrossRef]

M. T. Gale, " Replication techniques for diffractive optical elements," Microelectron. Eng. 34, 321- 339 ( 1997).
[CrossRef]

Hane, K.

Harbers, G.

G. Harbers, W. Timmers, and W. Sillevis-Smitt, " LED backlighting for LCD HDTV," J. Soc. Inf. Disp. 10, 347- 350 ( 2002).
[CrossRef]

Hirai, Y.

Hockel, H.

J. D. Brown, A. Mehta, and H. Hockel, " Improved fabrication accuracy of Bragg gratings," in Micromachining Technology for Micro-Optics and Nano-Optics, E. G. Johnson, G. P. Nordin, and T. J. Suleski, eds., Proc. SPIE 5720, 139- 147 ( 2005).

Holmes, D.

Y. Wang, T. Flaim, R. Mercado, S. Fowler, D. Holmes, and C. Planje, " Hybrid high refractive index polymer coatings," in Organic Photonic Materials and Devices VII, J. G. Grote, T. Kaino, and F. Kajzar, eds., Proc SPIE 5724, 42- 49 ( 2005).

R. Mercado, R. Rich, W. -S. Shih, U. Senapati, and D. Holmes, " Press-patterned diffraction gratings on high refractive index polyimide films," in Terahertz and Gigahertz Electronics and Photonics IV, R. J. Hwu and K. J. Linden, eds., Proc. SPIE 5728, 227- 236 ( 2005).

Hutley, M.

M. Hutley, Diffraction Gratings (Academic, 1982).

Iwata, K.

Jefimovs, K.

Jin, G. -F.

D. -E. Yi, Y. -B. Yan, H. -T. Liu, Si -Lu, and G. -F. Jin, " Broadband achromatic phase retarder by subwavelength grating," Opt. Commun. 227, 49- 55 ( 2003).
[CrossRef]

Jonsson, J. C.

J. C. Jonsson and F. Nikolajeff, " Optical properties of injection molded subwavelength gratings," Opt. Express. 12, 1924- 1931 ( 2004).
[CrossRef] [PubMed]

Kallioniemi, I.

M. Rossi and I. Kallioniemi, " Micro-optical modules fabricated by high-precision replication processes," in Diffractive Optics and Micro-Optics, Vol. 75 of OSA Proceedings Series (Optical Society of America, Washington, 2002), pp. 108- 110.

Kanamori, Y.

Kelly, K. L.

Kikuta, H.

Kintaka, K.

Kuittinen, M.

Laakkonen, P.

Lajunen, H.

Lalanne, P.

Lee, M. -S.

Liu, H. -T.

D. -E. Yi, Y. -B. Yan, H. -T. Liu, Si -Lu, and G. -F. Jin, " Broadband achromatic phase retarder by subwavelength grating," Opt. Commun. 227, 49- 55 ( 2003).
[CrossRef]

Mehta, A.

J. D. Brown, A. Mehta, and H. Hockel, " Improved fabrication accuracy of Bragg gratings," in Micromachining Technology for Micro-Optics and Nano-Optics, E. G. Johnson, G. P. Nordin, and T. J. Suleski, eds., Proc. SPIE 5720, 139- 147 ( 2005).

Mercado, R.

R. Mercado, R. Rich, W. -S. Shih, U. Senapati, and D. Holmes, " Press-patterned diffraction gratings on high refractive index polyimide films," in Terahertz and Gigahertz Electronics and Photonics IV, R. J. Hwu and K. J. Linden, eds., Proc. SPIE 5728, 227- 236 ( 2005).

Y. Wang, T. Flaim, R. Mercado, S. Fowler, D. Holmes, and C. Planje, " Hybrid high refractive index polymer coatings," in Organic Photonic Materials and Devices VII, J. G. Grote, T. Kaino, and F. Kajzar, eds., Proc SPIE 5724, 42- 49 ( 2005).

Miller, M.

Mönkkönen, K.

Nakazawa, T.

Nikolajeff, F.

J. C. Jonsson and F. Nikolajeff, " Optical properties of injection molded subwavelength gratings," Opt. Express. 12, 1924- 1931 ( 2004).
[CrossRef] [PubMed]

Nishii, J.

Nordin, G. P.

Ohira, Y.

Okano, M.

Orpana, A.

Parikka, M.

Parkyn, W. A.

W. A. Parkyn, D. G. Pelka, and J. Popovich, " The Black HoleTM: cuspated lightguide-injectors and illuminators for LEDs," in Nonimaging Optics: Maximum Efficiency Light TransferV,R.Winston, ed., Proc. SPIE 3781, 183- 189 ( 1999).

Pedersen, J.

M. T. Gale, J. Pedersen, and H. Schutz, " Active alignment of replicated microlens arrays on a charge-coupled device imager," Opt. Eng. 36, 151015 ( 1997).
[CrossRef]

Pelka, D. G.

W. A. Parkyn, D. G. Pelka, and J. Popovich, " The Black HoleTM: cuspated lightguide-injectors and illuminators for LEDs," in Nonimaging Optics: Maximum Efficiency Light TransferV,R.Winston, ed., Proc. SPIE 3781, 183- 189 ( 1999).

Planje, C.

Y. Wang, T. Flaim, R. Mercado, S. Fowler, D. Holmes, and C. Planje, " Hybrid high refractive index polymer coatings," in Organic Photonic Materials and Devices VII, J. G. Grote, T. Kaino, and F. Kajzar, eds., Proc SPIE 5724, 42- 49 ( 2005).

Popovich, J.

W. A. Parkyn, D. G. Pelka, and J. Popovich, " The Black HoleTM: cuspated lightguide-injectors and illuminators for LEDs," in Nonimaging Optics: Maximum Efficiency Light TransferV,R.Winston, ed., Proc. SPIE 3781, 183- 189 ( 1999).

Rich, R.

R. Mercado, R. Rich, W. -S. Shih, U. Senapati, and D. Holmes, " Press-patterned diffraction gratings on high refractive index polyimide films," in Terahertz and Gigahertz Electronics and Photonics IV, R. J. Hwu and K. J. Linden, eds., Proc. SPIE 5728, 227- 236 ( 2005).

Rossi, M.

M. Rossi and I. Kallioniemi, " Micro-optical modules fabricated by high-precision replication processes," in Diffractive Optics and Micro-Optics, Vol. 75 of OSA Proceedings Series (Optical Society of America, Washington, 2002), pp. 108- 110.

Sasaki, M.

Sauvan, C.

Schutz, H.

M. T. Gale, J. Pedersen, and H. Schutz, " Active alignment of replicated microlens arrays on a charge-coupled device imager," Opt. Eng. 36, 151015 ( 1997).
[CrossRef]

Senapati, U.

R. Mercado, R. Rich, W. -S. Shih, U. Senapati, and D. Holmes, " Press-patterned diffraction gratings on high refractive index polyimide films," in Terahertz and Gigahertz Electronics and Photonics IV, R. J. Hwu and K. J. Linden, eds., Proc. SPIE 5728, 227- 236 ( 2005).

Shih, W. -S.

R. Mercado, R. Rich, W. -S. Shih, U. Senapati, and D. Holmes, " Press-patterned diffraction gratings on high refractive index polyimide films," in Terahertz and Gigahertz Electronics and Photonics IV, R. J. Hwu and K. J. Linden, eds., Proc. SPIE 5728, 227- 236 ( 2005).

Siitonen, S.

Sillevis-Smitt, W.

G. Harbers, W. Timmers, and W. Sillevis-Smitt, " LED backlighting for LCD HDTV," J. Soc. Inf. Disp. 10, 347- 350 ( 2002).
[CrossRef]

Stiles, W. S.

G. Wyszecki and W. S. Stiles, Color Science: Concepts and Methods, Quantitative Data and Formulae, 2nd ed. (Wiley, 1982).

Tervo, J.

Timmers, W.

G. Harbers, W. Timmers, and W. Sillevis-Smitt, " LED backlighting for LCD HDTV," J. Soc. Inf. Disp. 10, 347- 350 ( 2002).
[CrossRef]

Turunen, J.

Vahimaa, P.

Wang, Y.

Y. Wang, T. Flaim, R. Mercado, S. Fowler, D. Holmes, and C. Planje, " Hybrid high refractive index polymer coatings," in Organic Photonic Materials and Devices VII, J. G. Grote, T. Kaino, and F. Kajzar, eds., Proc SPIE 5724, 42- 49 ( 2005).

Wyszecki, G.

G. Wyszecki and W. S. Stiles, Color Science: Concepts and Methods, Quantitative Data and Formulae, 2nd ed. (Wiley, 1982).

Yamamoto, K.

Yan, Y. -B.

D. -E. Yi, Y. -B. Yan, H. -T. Liu, Si -Lu, and G. -F. Jin, " Broadband achromatic phase retarder by subwavelength grating," Opt. Commun. 227, 49- 55 ( 2003).
[CrossRef]

Yi, D. -E.

D. -E. Yi, Y. -B. Yan, H. -T. Liu, Si -Lu, and G. -F. Jin, " Broadband achromatic phase retarder by subwavelength grating," Opt. Commun. 227, 49- 55 ( 2003).
[CrossRef]

Yotsuya, T.

Appl. Opt.

J. Opt. Soc. Am.

J. Soc. Inf. Disp.

G. Harbers, W. Timmers, and W. Sillevis-Smitt, " LED backlighting for LCD HDTV," J. Soc. Inf. Disp. 10, 347- 350 ( 2002).
[CrossRef]

Microelectron. Eng.

M. T. Gale, " Replication techniques for diffractive optical elements," Microelectron. Eng. 34, 321- 339 ( 1997).
[CrossRef]

Opt. Commun.

D. -E. Yi, Y. -B. Yan, H. -T. Liu, Si -Lu, and G. -F. Jin, " Broadband achromatic phase retarder by subwavelength grating," Opt. Commun. 227, 49- 55 ( 2003).
[CrossRef]

Opt. Eng.

M. T. Gale, J. Pedersen, and H. Schutz, " Active alignment of replicated microlens arrays on a charge-coupled device imager," Opt. Eng. 36, 151015 ( 1997).
[CrossRef]

Opt. Express

Opt. Express.

J. C. Jonsson and F. Nikolajeff, " Optical properties of injection molded subwavelength gratings," Opt. Express. 12, 1924- 1931 ( 2004).
[CrossRef] [PubMed]

Opt. Lett.

SID Symp. Digest

W. Folkerts, " LED backlighting concepts with hight flux LEDs," SID Symp. Digest 35, 1226- 1229 ( 2004).
[CrossRef]

Other

W. A. Parkyn, D. G. Pelka, and J. Popovich, " The Black HoleTM: cuspated lightguide-injectors and illuminators for LEDs," in Nonimaging Optics: Maximum Efficiency Light TransferV,R.Winston, ed., Proc. SPIE 3781, 183- 189 ( 1999).

M. Rossi and I. Kallioniemi, " Micro-optical modules fabricated by high-precision replication processes," in Diffractive Optics and Micro-Optics, Vol. 75 of OSA Proceedings Series (Optical Society of America, Washington, 2002), pp. 108- 110.

G. Wyszecki and W. S. Stiles, Color Science: Concepts and Methods, Quantitative Data and Formulae, 2nd ed. (Wiley, 1982).

J. Turunen, "Diffraction theory of microrelief gratings," Micro-optics: Elements, Systems, and Applications, H. P. Herzig, ed. (Taylor & Francis, 1997), Chap. 2.

R. Mercado, R. Rich, W. -S. Shih, U. Senapati, and D. Holmes, " Press-patterned diffraction gratings on high refractive index polyimide films," in Terahertz and Gigahertz Electronics and Photonics IV, R. J. Hwu and K. J. Linden, eds., Proc. SPIE 5728, 227- 236 ( 2005).

Y. Wang, T. Flaim, R. Mercado, S. Fowler, D. Holmes, and C. Planje, " Hybrid high refractive index polymer coatings," in Organic Photonic Materials and Devices VII, J. G. Grote, T. Kaino, and F. Kajzar, eds., Proc SPIE 5724, 42- 49 ( 2005).

Comission Internationale de l'Eclairage, Proceedings of the Eighth Session (Comission Internationale de l'Eclairage, Vienna, 1931), pp. 19- 29.

M. Hutley, Diffraction Gratings (Academic, 1982).

J. D. Brown, A. Mehta, and H. Hockel, " Improved fabrication accuracy of Bragg gratings," in Micromachining Technology for Micro-Optics and Nano-Optics, E. G. Johnson, G. P. Nordin, and T. J. Suleski, eds., Proc. SPIE 5720, 139- 147 ( 2005).

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Figures (10)

Fig. 1
Fig. 1

(a) Geometry of the grating coupler. (b) Geometry of the coupler gratings. For an explanation of the notation, see text.

Fig. 2
Fig. 2

Spectral coupling efficiencies for four refractive indices. A typical radiance spectrum (in A.U.) of a white fluorescence LED is also shown.

Fig. 3
Fig. 3

Theoretical spectra of incoupled white LED light for four refractive indices and the spectrum of a white fluorescence LED.

Fig. 4
Fig. 4

Theoretical color coordinates of incoupled white LED light for four refractive indices: □, emission color of a white fluorescence LED, ○, n = 2.05, ♢, n = 1.76, ∗, n = 1.562, +, n = 1.462. An area outlined by a dashed curve illustrates the white domain of the CIE 1931 chromaticity diagram.[20, 21]

Fig. 5
Fig. 5

Scanning-electron microscope picture of the replica of the fabricated coupler.

Fig. 6
Fig. 6

Incoupling efficiency as a function of wavelength for five grating fill factors. Theoretical total incoupling efficiencies ηtot are given in the inset.

Fig. 7
Fig. 7

Experimental measurement of I 0, I 1, and I 2 with an integrating sphere.

Fig. 8
Fig. 8

Experimental and calculated diffraction efficiencies of a white LED and red (λ = 630 nm), green (λ = 550), and blue (λ = 470) LEDs for the fabricated SiO2 and NOA couplers.

Fig. 9
Fig. 9

Measured spectra of I 0, I 1, and I 2, the numerical solvent incoupling spectrum, and the theoretical incoupling spectrum.

Fig. 10
Fig. 10

Theoretical (×) and experimental (□) color coordinates for the SiO2 coupler and emission color of a white fluorescence LED (○). An area outlined by a dashed curve illustrates the white domain of the CIE 1931 chromaticity diagram.[25, 26]

Tables (1)

Tables Icon

Table 1 Theoretical Incoupling Efficiency ηλ for Wavelengths 470, 550, and 630 nm in the Pure Conical Mounting Situation a

Equations (5)

Equations on this page are rendered with MathJax. Learn more.

P ( ϕ ) = sin 2 ( ϕ ) .
η = 1 K m M l L η ( λ m , ϕ l ) P ( Δ ϕ l ) ,
η ( λ m , ϕ l ) = [ η ( λ m , ϕ l ) TE + η ( λ m , ϕ l ) TM ] / 2 ,
d l     max = λ B / cos θ in , l ,
η I 2 I 1 I 0 I 2 / I 0 .

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