Abstract

A spatial light modulator with a thin (1-μm) amorphous silicon (PIN) photoconductor has been demonstrated with a threshold sensitivity of <3 μw/cm2. A novel compound electrode design greatly increases the efficiency allowing the use of a photoconductive layer thin enough to achieve good transmission. The performance characteristics are reported and compared to the predictions of a theoretical model of the device.

© 1988 Optical Society of America

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References

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  1. P. R. Ashley, J. H. Davis, “Amorphous Silicon Photoconductor in a Liquid Crystal Spatial Light Modulator,” Appl. Opt. 26, 241 (1987).
    [CrossRef] [PubMed]
  2. G. Moddel, K. M. Johnson, M. A. Handschy, “Photoad-dressing of High Speed Liquid Light Spatial Light Modulators,” Proc. Soc. Photo-Opt. Instrum. Eng. 754, 36 (1987).
  3. J. G. Duthie, J. Upatnieks, C. R. Christensen, R. D. McKenzie, “Real-Time Optical Correlation with Solid-State Sources,” Proc. Soc. Photo-Opt. Instrum. Eng. 231, 281 (1980).
  4. J. Upatnieks, “Portable Real-Time Coherent Optical Correlator,” App. Opt. 22, 2798 (1983).
    [CrossRef]
  5. J. G. Duthie, J. Upatnieks, “Compact Real-Time Coherent Optical Correlators,” Opt. Eng. 23, 007 (1984).
    [CrossRef]
  6. J. Grinberg, A. Jacobson, W. P. Bleha, L. Miller, L. Fraas, D. Boswell, G. Myer, “New Real-Time Noncoherent to Coherent Light Image Converter: Hybrid Field Effect Liquid Crystal Light Valve,” Opt. Eng. 14, 217 (1975).
    [CrossRef]
  7. J. Grinberg et al., “Photoactivated Birefringent Liquid-Crystal Light Valve for Color Symbology Display,” IEEE Trans. Electron Devices ED-22, 775 (1975).
    [CrossRef]
  8. U. Efron, J. Grinberg, P. O. Braatz, M. J. Little, P. G. Reif, R. N. Schwartz, “The Silicon Liquid-Crystal Light Valve,” J. Appl. Phys. 57, 1356 (1985).
    [CrossRef]
  9. G. D. Dixon, T. P. Brody, W. A. Hester, “Alignment Mechanism in Twisted Nematic Layers,” Appl. Phys. Lett. 24, No. 2, 15 (1974).
    [CrossRef]
  10. T. K. Oh, “The Hydrogenated Amorphous Silicon Photoconductor Coupled Liquid Crystal Light Valve,” Ph.D. Dissertation, U. Alabama in Huntsville (1987).
  11. G. A. Swartz, “Computer Model of Amorphous Silicon Solar Cell,” J. Appl. Phys. 53, 712 (1982).
    [CrossRef]

1987

P. R. Ashley, J. H. Davis, “Amorphous Silicon Photoconductor in a Liquid Crystal Spatial Light Modulator,” Appl. Opt. 26, 241 (1987).
[CrossRef] [PubMed]

G. Moddel, K. M. Johnson, M. A. Handschy, “Photoad-dressing of High Speed Liquid Light Spatial Light Modulators,” Proc. Soc. Photo-Opt. Instrum. Eng. 754, 36 (1987).

1985

U. Efron, J. Grinberg, P. O. Braatz, M. J. Little, P. G. Reif, R. N. Schwartz, “The Silicon Liquid-Crystal Light Valve,” J. Appl. Phys. 57, 1356 (1985).
[CrossRef]

1984

J. G. Duthie, J. Upatnieks, “Compact Real-Time Coherent Optical Correlators,” Opt. Eng. 23, 007 (1984).
[CrossRef]

1983

J. Upatnieks, “Portable Real-Time Coherent Optical Correlator,” App. Opt. 22, 2798 (1983).
[CrossRef]

1982

G. A. Swartz, “Computer Model of Amorphous Silicon Solar Cell,” J. Appl. Phys. 53, 712 (1982).
[CrossRef]

1980

J. G. Duthie, J. Upatnieks, C. R. Christensen, R. D. McKenzie, “Real-Time Optical Correlation with Solid-State Sources,” Proc. Soc. Photo-Opt. Instrum. Eng. 231, 281 (1980).

1975

J. Grinberg, A. Jacobson, W. P. Bleha, L. Miller, L. Fraas, D. Boswell, G. Myer, “New Real-Time Noncoherent to Coherent Light Image Converter: Hybrid Field Effect Liquid Crystal Light Valve,” Opt. Eng. 14, 217 (1975).
[CrossRef]

J. Grinberg et al., “Photoactivated Birefringent Liquid-Crystal Light Valve for Color Symbology Display,” IEEE Trans. Electron Devices ED-22, 775 (1975).
[CrossRef]

1974

G. D. Dixon, T. P. Brody, W. A. Hester, “Alignment Mechanism in Twisted Nematic Layers,” Appl. Phys. Lett. 24, No. 2, 15 (1974).
[CrossRef]

Ashley, P. R.

Bleha, W. P.

J. Grinberg, A. Jacobson, W. P. Bleha, L. Miller, L. Fraas, D. Boswell, G. Myer, “New Real-Time Noncoherent to Coherent Light Image Converter: Hybrid Field Effect Liquid Crystal Light Valve,” Opt. Eng. 14, 217 (1975).
[CrossRef]

Boswell, D.

J. Grinberg, A. Jacobson, W. P. Bleha, L. Miller, L. Fraas, D. Boswell, G. Myer, “New Real-Time Noncoherent to Coherent Light Image Converter: Hybrid Field Effect Liquid Crystal Light Valve,” Opt. Eng. 14, 217 (1975).
[CrossRef]

Braatz, P. O.

U. Efron, J. Grinberg, P. O. Braatz, M. J. Little, P. G. Reif, R. N. Schwartz, “The Silicon Liquid-Crystal Light Valve,” J. Appl. Phys. 57, 1356 (1985).
[CrossRef]

Brody, T. P.

G. D. Dixon, T. P. Brody, W. A. Hester, “Alignment Mechanism in Twisted Nematic Layers,” Appl. Phys. Lett. 24, No. 2, 15 (1974).
[CrossRef]

Christensen, C. R.

J. G. Duthie, J. Upatnieks, C. R. Christensen, R. D. McKenzie, “Real-Time Optical Correlation with Solid-State Sources,” Proc. Soc. Photo-Opt. Instrum. Eng. 231, 281 (1980).

Davis, J. H.

Dixon, G. D.

G. D. Dixon, T. P. Brody, W. A. Hester, “Alignment Mechanism in Twisted Nematic Layers,” Appl. Phys. Lett. 24, No. 2, 15 (1974).
[CrossRef]

Duthie, J. G.

J. G. Duthie, J. Upatnieks, “Compact Real-Time Coherent Optical Correlators,” Opt. Eng. 23, 007 (1984).
[CrossRef]

J. G. Duthie, J. Upatnieks, C. R. Christensen, R. D. McKenzie, “Real-Time Optical Correlation with Solid-State Sources,” Proc. Soc. Photo-Opt. Instrum. Eng. 231, 281 (1980).

Efron, U.

U. Efron, J. Grinberg, P. O. Braatz, M. J. Little, P. G. Reif, R. N. Schwartz, “The Silicon Liquid-Crystal Light Valve,” J. Appl. Phys. 57, 1356 (1985).
[CrossRef]

Fraas, L.

J. Grinberg, A. Jacobson, W. P. Bleha, L. Miller, L. Fraas, D. Boswell, G. Myer, “New Real-Time Noncoherent to Coherent Light Image Converter: Hybrid Field Effect Liquid Crystal Light Valve,” Opt. Eng. 14, 217 (1975).
[CrossRef]

Grinberg, J.

U. Efron, J. Grinberg, P. O. Braatz, M. J. Little, P. G. Reif, R. N. Schwartz, “The Silicon Liquid-Crystal Light Valve,” J. Appl. Phys. 57, 1356 (1985).
[CrossRef]

J. Grinberg et al., “Photoactivated Birefringent Liquid-Crystal Light Valve for Color Symbology Display,” IEEE Trans. Electron Devices ED-22, 775 (1975).
[CrossRef]

J. Grinberg, A. Jacobson, W. P. Bleha, L. Miller, L. Fraas, D. Boswell, G. Myer, “New Real-Time Noncoherent to Coherent Light Image Converter: Hybrid Field Effect Liquid Crystal Light Valve,” Opt. Eng. 14, 217 (1975).
[CrossRef]

Handschy, M. A.

G. Moddel, K. M. Johnson, M. A. Handschy, “Photoad-dressing of High Speed Liquid Light Spatial Light Modulators,” Proc. Soc. Photo-Opt. Instrum. Eng. 754, 36 (1987).

Hester, W. A.

G. D. Dixon, T. P. Brody, W. A. Hester, “Alignment Mechanism in Twisted Nematic Layers,” Appl. Phys. Lett. 24, No. 2, 15 (1974).
[CrossRef]

Jacobson, A.

J. Grinberg, A. Jacobson, W. P. Bleha, L. Miller, L. Fraas, D. Boswell, G. Myer, “New Real-Time Noncoherent to Coherent Light Image Converter: Hybrid Field Effect Liquid Crystal Light Valve,” Opt. Eng. 14, 217 (1975).
[CrossRef]

Johnson, K. M.

G. Moddel, K. M. Johnson, M. A. Handschy, “Photoad-dressing of High Speed Liquid Light Spatial Light Modulators,” Proc. Soc. Photo-Opt. Instrum. Eng. 754, 36 (1987).

Little, M. J.

U. Efron, J. Grinberg, P. O. Braatz, M. J. Little, P. G. Reif, R. N. Schwartz, “The Silicon Liquid-Crystal Light Valve,” J. Appl. Phys. 57, 1356 (1985).
[CrossRef]

McKenzie, R. D.

J. G. Duthie, J. Upatnieks, C. R. Christensen, R. D. McKenzie, “Real-Time Optical Correlation with Solid-State Sources,” Proc. Soc. Photo-Opt. Instrum. Eng. 231, 281 (1980).

Miller, L.

J. Grinberg, A. Jacobson, W. P. Bleha, L. Miller, L. Fraas, D. Boswell, G. Myer, “New Real-Time Noncoherent to Coherent Light Image Converter: Hybrid Field Effect Liquid Crystal Light Valve,” Opt. Eng. 14, 217 (1975).
[CrossRef]

Moddel, G.

G. Moddel, K. M. Johnson, M. A. Handschy, “Photoad-dressing of High Speed Liquid Light Spatial Light Modulators,” Proc. Soc. Photo-Opt. Instrum. Eng. 754, 36 (1987).

Myer, G.

J. Grinberg, A. Jacobson, W. P. Bleha, L. Miller, L. Fraas, D. Boswell, G. Myer, “New Real-Time Noncoherent to Coherent Light Image Converter: Hybrid Field Effect Liquid Crystal Light Valve,” Opt. Eng. 14, 217 (1975).
[CrossRef]

Oh, T. K.

T. K. Oh, “The Hydrogenated Amorphous Silicon Photoconductor Coupled Liquid Crystal Light Valve,” Ph.D. Dissertation, U. Alabama in Huntsville (1987).

Reif, P. G.

U. Efron, J. Grinberg, P. O. Braatz, M. J. Little, P. G. Reif, R. N. Schwartz, “The Silicon Liquid-Crystal Light Valve,” J. Appl. Phys. 57, 1356 (1985).
[CrossRef]

Schwartz, R. N.

U. Efron, J. Grinberg, P. O. Braatz, M. J. Little, P. G. Reif, R. N. Schwartz, “The Silicon Liquid-Crystal Light Valve,” J. Appl. Phys. 57, 1356 (1985).
[CrossRef]

Swartz, G. A.

G. A. Swartz, “Computer Model of Amorphous Silicon Solar Cell,” J. Appl. Phys. 53, 712 (1982).
[CrossRef]

Upatnieks, J.

J. G. Duthie, J. Upatnieks, “Compact Real-Time Coherent Optical Correlators,” Opt. Eng. 23, 007 (1984).
[CrossRef]

J. Upatnieks, “Portable Real-Time Coherent Optical Correlator,” App. Opt. 22, 2798 (1983).
[CrossRef]

J. G. Duthie, J. Upatnieks, C. R. Christensen, R. D. McKenzie, “Real-Time Optical Correlation with Solid-State Sources,” Proc. Soc. Photo-Opt. Instrum. Eng. 231, 281 (1980).

App. Opt.

J. Upatnieks, “Portable Real-Time Coherent Optical Correlator,” App. Opt. 22, 2798 (1983).
[CrossRef]

Appl. Opt.

Appl. Phys. Lett.

G. D. Dixon, T. P. Brody, W. A. Hester, “Alignment Mechanism in Twisted Nematic Layers,” Appl. Phys. Lett. 24, No. 2, 15 (1974).
[CrossRef]

IEEE Trans. Electron Devices

J. Grinberg et al., “Photoactivated Birefringent Liquid-Crystal Light Valve for Color Symbology Display,” IEEE Trans. Electron Devices ED-22, 775 (1975).
[CrossRef]

J. Appl. Phys.

U. Efron, J. Grinberg, P. O. Braatz, M. J. Little, P. G. Reif, R. N. Schwartz, “The Silicon Liquid-Crystal Light Valve,” J. Appl. Phys. 57, 1356 (1985).
[CrossRef]

G. A. Swartz, “Computer Model of Amorphous Silicon Solar Cell,” J. Appl. Phys. 53, 712 (1982).
[CrossRef]

Opt. Eng.

J. G. Duthie, J. Upatnieks, “Compact Real-Time Coherent Optical Correlators,” Opt. Eng. 23, 007 (1984).
[CrossRef]

J. Grinberg, A. Jacobson, W. P. Bleha, L. Miller, L. Fraas, D. Boswell, G. Myer, “New Real-Time Noncoherent to Coherent Light Image Converter: Hybrid Field Effect Liquid Crystal Light Valve,” Opt. Eng. 14, 217 (1975).
[CrossRef]

Proc. Soc. Photo-Opt. Instrum. Eng.

G. Moddel, K. M. Johnson, M. A. Handschy, “Photoad-dressing of High Speed Liquid Light Spatial Light Modulators,” Proc. Soc. Photo-Opt. Instrum. Eng. 754, 36 (1987).

J. G. Duthie, J. Upatnieks, C. R. Christensen, R. D. McKenzie, “Real-Time Optical Correlation with Solid-State Sources,” Proc. Soc. Photo-Opt. Instrum. Eng. 231, 281 (1980).

Other

T. K. Oh, “The Hydrogenated Amorphous Silicon Photoconductor Coupled Liquid Crystal Light Valve,” Ph.D. Dissertation, U. Alabama in Huntsville (1987).

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Figures (13)

Fig. 1
Fig. 1

Construction diagram of the triple electrode amorphous silicon spatial light modulator.

Fig. 2
Fig. 2

Lumped element electrical model of the a-Si:H liquid crystal spatial light modulator with a cross-sectional view showing unit cell subdivision.

Fig. 3
Fig. 3

Reverse bias I–V characteristics of the amorphous silicon photodiode as a function of white light intensity ϕ. The thickness of the intrinsic layer is 1.2 μm.

Fig. 4
Fig. 4

The dc voltage at the gap center as a function of the gap width for various write light intensities. The electrode bias potential is 3.8 V.

Fig. 5
Fig. 5

The ac voltage amplitude at the gap center as a function of frequency for various white light intensities and gap widths. The input ac signal amplitude is 1 V.

Fig. 6
Fig. 6

Typical time response of a liquid crystal modulator showing read light ouput as a function of write light intensity. The gap width is 25 μm Decay time of ~90 ms, which is strongly dependent on LC drive conditions, alignment, and cell design, should not be assumed as optimum.

Fig. 7
Fig. 7

Transfer curve of a 90° twist BDH-E44 liquid crystal in the transmission mode. The analyzer was adjusted for extinction with no voltage applied.

Fig. 8
Fig. 8

Device sensitometry curves. The inserted numbers indicate the gap and the electrode voltages. The electrode width is fixed at 12.5 μm.

Fig. 9
Fig. 9

Setup diagram for testing the transmission mode of the amorphous silicon spatial light modulator.

Fig. 10
Fig. 10

Device transmission as a function of distance from the electrode edge for various values of write light intensity. The gap space is 100 μm and the electrode bias potential is 3.8 V.

Fig. 11
Fig. 11

Comparison of the theoretical and measured device transmission at two locations, 25 and 50 μm, from the center electrode edge. The gap space is 100 μm. The applied bias potential is 3.8 V.

Fig. 12
Fig. 12

White light input and read light output intensity vs time for the 25-μm gap width.

Fig. 13
Fig. 13

Optical output of a spoked wheel test pattern with 25-μm modulator gap width in (a) and bar chart with 100-μm modulator gap width in (b).

Equations (4)

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[ S ] [ V 1 ( ϕ ) · · · V 40 ( ϕ ) ] = [ I 1 ( V , ϕ ) + V 0 / R AS 1 · · · I 40 ( V , ϕ ) ] ,
I i ( V , ϕ ) = s ( ϕ ) V i + b ( ϕ ) ,
[ V 1 · · · V 40 ] = { [ S ] [ S ( ϕ ) · · · S ( ϕ ) ] } 1 [ b ( ϕ ) + V 0 / R AS 1 · · · b ( ϕ ) ]
[ Y ] [ V 1 sin ω t · · · V 40 sin ω t ] = [ I 1 + V 0 / R AS 1 sin ω t · · · I 40 sin ω t ] ,

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