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Photochromic fulgide for holographic recording
Optical Materials 26 (2004) 75–77 www.elsevier.com/locate/optmat
Photochromic fulgide for holographic recording Yi Chen
a,*
, Congming Wang a, Meigong Fan a, Baoli Yao b, Neimule Menke
b
a b
Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100101, PR China State Key Laboratory of Transient Optics Technology, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi’an 710068, PR China Received 3 December 2003 Available online 27 February 2004
Abstract (N-40 -methoxy-2-methyl-5-phenyl)-3-pyrryl-ethylidene (isopropylidene) succinic anhydride fulgide, doped in PMMA matrix, exhibits photochromic behavior. The fatigue resistance experiment shows no photodegradation is detected after more than 450 writing–erasing cycles. Study of fulgide material for holographic recording media shows the optimal exposure and the diffraction efficiency is 1047 mJ/cm2 and 2.26%, respectively, with 10 lm thickness polymer film. Holographic grating with 1680 lines/mm at writing angle h ¼ 30 is also obtained. 2004 Elsevier B.V. All rights reserved. PACS: 78.20.W Keywords: Photochromic fulgide; Holographic recording; Optical storage
1. Introduction With the increasing requirements of the huge information storage, the demands for highly speed input and larger memory capacity are becoming mandatory. Holographic recording is to be one of important optical memories because of its advantages of large capacity and high speed of input and output of information. Development and commercialization of holographic recording depend, in large extent, on recording materials. Although there are two main classes of materials reported [1–4] for holographic recording, one is photorefractive materials and another photosensitive polymerizable acrylic materials. The shortcomings of both kinds of materials are manifest, such as slow response time for photorefractive materials and special fixing information after recording for photosensitive polymerizable acrylic materials. The disadvantages above, however, can be overcome when organic photochromic materials are used for holographic recording.
*
Corresponding author. Tel.: +86-10-6488-8172; fax: +86-10-64879375. E-mail address: [email protected] (Y. Chen). 0925-3467/$ - see front matter 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.optmat.2004.01.004
Organic photochromic compounds are one kind of candidates for optical memory [5–7], especially for rewritable optical memory. Upon photoirradiation photochromic compounds reversibly change not only the absorption spectra but also other physicochemical properties, such as refractive index, electrical moment, dielectric constants, chelate formation, ion dissociation, oxidation/reduction potentials and phase transitions during the photochromic reaction. There are some advantages of photochromic materials for holographic recording: (1) fast response time, (2) high spatial resolution, (3) re-writability, and (4) without special fixing information. Fulgides, a kind of photochromic systems and first reported by Stobbe [8], have attracted extent interesting and lots of papers are reported on synthesis, properties and potential photoelectronic applications [9– 11] because of the fatigue resistance and thermally irreversibility. However, among them there are few publications that contribute to holographic recording. Recently, Belfield et al. [12] reported two-photon photochromism of indolylfulgide for holographic recording. In this paper, the photochromic properties of (N-40 -methoxy-2-methyl-5-phenyl)-3-pyrryl fulgide doped in PMMA matrix are investigated and application for holographic recording media is firstly presented.
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Y. Chen et al. / Optical Materials 26 (2004) 75–77
2. Experiment 1
H-NMR is obtained from a Varian Germina-300 spectrometer. MS is measured with a Trio-2000 GC-MS spectrometry. Absorption spectra are recorded on a Hitachi U-3010 UV–Visible spectrometer at room temperature. A lower-pressure mercury lamp (30 W) is used as light source for the photocoloration. The photochromic fulgide-PMMA film is prepared as follows: The target compound (3 mg) is dissolved in a 0.l ml PMMA–cyclohexanone solution (10%, w/w). The film is obtained by spreading of the fulgide-PMMA solution on a optical glass (25 mm · 25 mm · 1.5 mm) and dried in air and kept in darkness at room temperature. The thickness of the film is about 10 lm. Holographic recording is carried out by the setup described in Fig. 1. IO and IC represent the intensity of the object beam and the recovery beam, respectively, IR and IS are the reference beam and diffraction beam, respectively, and t is exposure time.
O
O O N O
O
UV N Vis
O
OCH3
OCH3
open-form
closed-form
Scheme 1. Photoisomerization of fulgide.
3. Results and discussion 3.1. Photochromic behavior of fulgide 3.1.1. Chemical material (N-40 -methoxy-2-methyl-5-phenyl)-3-pyrryl-ethylidene (isopropylidene) succinic anhydride fulgide is prepared by Stobbe reaction [8] from N-40 -methoxyphenyl-2-methyl-5-phenyl-3-acetyl-pyrrole and diethyl isopropylidene succinate. Yield 6.1%; M.p. 178–180 C; C27 H25 NO4 , Cald. C: 75.86, H: 5.90, N: 3.28; found C: 75.68, H: 5.97, N: 3.08; 1 H-NMR(ppm, CDCl3 ), 7.20– 6.95(m, 9H, Ar–H), 6.45(s, 1H), 3.86(s, 3H, OCH3 ), 2.75(s, 3H, CH3 ), 2.41(s, 3H, CH3 ), 1.96(s, 3H, CH3 ), 1.45(s, 3H, CH3 ); m=z 427(Mþ ), 412(Mþ –CH3 ). 3.1.2. Absorption spectra of fulgide in PMMA matrix Photoisomerization of fulgide is illustrated by Scheme 1, and absorption spectra of fulgide-PMMA film before and after irradiation are shown in Fig. 2. As shown in Fig. 2, the absorption band at 373 nm, cor-
Fig. 1. Experimental setup for measuring the holographic properties of fulgide-PMMA film.
Fig. 2. Absorption spectra of fulgide in PMMA film before (––) and after ( ) irradiation.
responding to open form, disappears along with increase a new absorption band at 626 nm, which attributes to closed-form, companying the color of film changes from light yellow to blue upon irradiation with UV light. It is also found that both open-form and closed-form are stable at room temperature in darkness. 3.1.3. Fatigue resistance of fulgide The above fulgide-PMMA film is used for investigating the fatigue resistance. A plot of writing–erasing cycle number against reflectivity change is presented in Fig. 3. He–Ne laser and UV light are used as writing
Fig. 3. Fatigue resistance. (Up: writing, down: erasing. The power of writing is 36 mw; writing time is 1 s; the density of the writing light is 7.33 mJ/mm2 . The power of erasing light is 80 mw; erasing time is 3 s; the density of the erasing power is 2.18 mJ/mm2 .)
Y. Chen et al. / Optical Materials 26 (2004) 75–77
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3.2.2. The spatial resolution of fulgide-PMMA film Fig. 5 represents spatial resolution of fulgide-PMMA film for holographic recording. With a writing angle hw ¼ 30, holographic recording in fulgide-PMMA film gives a grating with N ¼ 1680 lines/mm.
4. Conclusion
Fig. 4. Dependence of the 1st-order diffraction efficiency on the exposure.
The photochromic properties of fulgide doped in PMMA are investigated and the closed form presents absorption band at 626 nm upon irradiation at 373 nm. Fatigue resistance of fulgide-PMMA film is performed by He–Ne laser and it shows the reflectivity is not markedly changed after 450 cycles of writing–erasing. Fulgide-PMMA used as holographic recording material is demonstrated. With a writing angle hw ¼ 30, holographic recording on fulgide-PMMA film, gives a grating with N ¼ 1680 lines/mm. The optimal exposure of 1047 mJ/cm2 and the first order diffraction efficiency g ¼ 2:26% with 10 lm thickness film are obtained.
Fig. 5. Interference fringes recorded on the fulgide-PMMA film (10 lm/div).
Acknowledgements light and erasing one, respectively. It is found that the reflectivity is not markedly changed after 450 cycles of writing–erasing and it indicates no photodegradation is detected after 450 writing–erasing cycles. 3.2. Holographic recording 3.2.1. The first order diffraction efficiency of fulgidePMMA film Holographic recording of a fulgide-PMMA film (thickness 10 lm) is investigated. The diffraction efficiency and the exposure energy are defined as the follow formula, respectively: g ¼ IS =IC ;
Exposure ¼ ðIO þ IR þ IC Þ t:
As shown in Fig. 4, the first order diffraction efficiency increased fast at beginning till the maximum value is obtained (g ¼ 2:26%) with an exposure of 1047 mJ/cm2 . It is known that the value of diffraction efficiency depended on the properties of material and other conditions such as the concentration of compound, the thickness of polymer film and intensity of writing beam.
The work was supported by National Science Foundation of China (no. 60277001 and no. 60337020) and National Principal Research Project ‘‘973’’ (G 1999033005).
References [1] V.P. Pharm, G. Manivannan, R.V. Lessard, Opt. Mater. 4 (1995) 467. [2] T. Weitzel, U. Wild, M. Amlung, H. Durr, M. Irie, Mol. Cryst. Liq. Crist. 344 (2000) 191. [3] V.V. Mogilny, Y.V. Gritsai, SPIE Proc. 340 (1998) 100. [4] T.H. Chao, H. Zhou, G. Reyes, SPIE Proc. 3864 (1999) 181. [5] Y. Yokoyama, Chem. Rev. 100 (2000) 1717. [6] M. Irie, Chem. Rev. 100 (2000) 1685. [7] S. Kawata, Y. Kawata, Chem. Rev. 100 (2000) 1777. [8] B.P. Munday, M.G. Ellerd, Name Reactions and Reagents in Organic Synthesis, John Wiley and Sons, New York, 1988. [9] H.G. Heller, IEE Proc. 130 (1983) 209. [10] M. Seibold, H. Port, K. Gustav, Chem. Phys. Lett. 314 (1999) 65. [11] F. Matsui, H. Taniquchi, Y. Yokoyama, K. Sugiyama, Y. Kurita, Chem. Lett. (1994) 1869. [12] K.D. Belfield, Y. Liu, R.A. Negres, M. Fan, G. Pan, D.J. Hagan, F.E. Hernandez, Chem. Mater. 14 (2002) 3663.
Photochromic fulgide for holographic recording Yi Chen
a,*
, Congming Wang a, Meigong Fan a, Baoli Yao b, Neimule Menke
b
a b
Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100101, PR China State Key Laboratory of Transient Optics Technology, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi’an 710068, PR China Received 3 December 2003 Available online 27 February 2004
Abstract (N-40 -methoxy-2-methyl-5-phenyl)-3-pyrryl-ethylidene (isopropylidene) succinic anhydride fulgide, doped in PMMA matrix, exhibits photochromic behavior. The fatigue resistance experiment shows no photodegradation is detected after more than 450 writing–erasing cycles. Study of fulgide material for holographic recording media shows the optimal exposure and the diffraction efficiency is 1047 mJ/cm2 and 2.26%, respectively, with 10 lm thickness polymer film. Holographic grating with 1680 lines/mm at writing angle h ¼ 30 is also obtained. 2004 Elsevier B.V. All rights reserved. PACS: 78.20.W Keywords: Photochromic fulgide; Holographic recording; Optical storage
1. Introduction With the increasing requirements of the huge information storage, the demands for highly speed input and larger memory capacity are becoming mandatory. Holographic recording is to be one of important optical memories because of its advantages of large capacity and high speed of input and output of information. Development and commercialization of holographic recording depend, in large extent, on recording materials. Although there are two main classes of materials reported [1–4] for holographic recording, one is photorefractive materials and another photosensitive polymerizable acrylic materials. The shortcomings of both kinds of materials are manifest, such as slow response time for photorefractive materials and special fixing information after recording for photosensitive polymerizable acrylic materials. The disadvantages above, however, can be overcome when organic photochromic materials are used for holographic recording.
*
Corresponding author. Tel.: +86-10-6488-8172; fax: +86-10-64879375. E-mail address: [email protected] (Y. Chen). 0925-3467/$ - see front matter 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.optmat.2004.01.004
Organic photochromic compounds are one kind of candidates for optical memory [5–7], especially for rewritable optical memory. Upon photoirradiation photochromic compounds reversibly change not only the absorption spectra but also other physicochemical properties, such as refractive index, electrical moment, dielectric constants, chelate formation, ion dissociation, oxidation/reduction potentials and phase transitions during the photochromic reaction. There are some advantages of photochromic materials for holographic recording: (1) fast response time, (2) high spatial resolution, (3) re-writability, and (4) without special fixing information. Fulgides, a kind of photochromic systems and first reported by Stobbe [8], have attracted extent interesting and lots of papers are reported on synthesis, properties and potential photoelectronic applications [9– 11] because of the fatigue resistance and thermally irreversibility. However, among them there are few publications that contribute to holographic recording. Recently, Belfield et al. [12] reported two-photon photochromism of indolylfulgide for holographic recording. In this paper, the photochromic properties of (N-40 -methoxy-2-methyl-5-phenyl)-3-pyrryl fulgide doped in PMMA matrix are investigated and application for holographic recording media is firstly presented.
76
Y. Chen et al. / Optical Materials 26 (2004) 75–77
2. Experiment 1
H-NMR is obtained from a Varian Germina-300 spectrometer. MS is measured with a Trio-2000 GC-MS spectrometry. Absorption spectra are recorded on a Hitachi U-3010 UV–Visible spectrometer at room temperature. A lower-pressure mercury lamp (30 W) is used as light source for the photocoloration. The photochromic fulgide-PMMA film is prepared as follows: The target compound (3 mg) is dissolved in a 0.l ml PMMA–cyclohexanone solution (10%, w/w). The film is obtained by spreading of the fulgide-PMMA solution on a optical glass (25 mm · 25 mm · 1.5 mm) and dried in air and kept in darkness at room temperature. The thickness of the film is about 10 lm. Holographic recording is carried out by the setup described in Fig. 1. IO and IC represent the intensity of the object beam and the recovery beam, respectively, IR and IS are the reference beam and diffraction beam, respectively, and t is exposure time.
O
O O N O
O
UV N Vis
O
OCH3
OCH3
open-form
closed-form
Scheme 1. Photoisomerization of fulgide.
3. Results and discussion 3.1. Photochromic behavior of fulgide 3.1.1. Chemical material (N-40 -methoxy-2-methyl-5-phenyl)-3-pyrryl-ethylidene (isopropylidene) succinic anhydride fulgide is prepared by Stobbe reaction [8] from N-40 -methoxyphenyl-2-methyl-5-phenyl-3-acetyl-pyrrole and diethyl isopropylidene succinate. Yield 6.1%; M.p. 178–180 C; C27 H25 NO4 , Cald. C: 75.86, H: 5.90, N: 3.28; found C: 75.68, H: 5.97, N: 3.08; 1 H-NMR(ppm, CDCl3 ), 7.20– 6.95(m, 9H, Ar–H), 6.45(s, 1H), 3.86(s, 3H, OCH3 ), 2.75(s, 3H, CH3 ), 2.41(s, 3H, CH3 ), 1.96(s, 3H, CH3 ), 1.45(s, 3H, CH3 ); m=z 427(Mþ ), 412(Mþ –CH3 ). 3.1.2. Absorption spectra of fulgide in PMMA matrix Photoisomerization of fulgide is illustrated by Scheme 1, and absorption spectra of fulgide-PMMA film before and after irradiation are shown in Fig. 2. As shown in Fig. 2, the absorption band at 373 nm, cor-
Fig. 1. Experimental setup for measuring the holographic properties of fulgide-PMMA film.
Fig. 2. Absorption spectra of fulgide in PMMA film before (––) and after ( ) irradiation.
responding to open form, disappears along with increase a new absorption band at 626 nm, which attributes to closed-form, companying the color of film changes from light yellow to blue upon irradiation with UV light. It is also found that both open-form and closed-form are stable at room temperature in darkness. 3.1.3. Fatigue resistance of fulgide The above fulgide-PMMA film is used for investigating the fatigue resistance. A plot of writing–erasing cycle number against reflectivity change is presented in Fig. 3. He–Ne laser and UV light are used as writing
Fig. 3. Fatigue resistance. (Up: writing, down: erasing. The power of writing is 36 mw; writing time is 1 s; the density of the writing light is 7.33 mJ/mm2 . The power of erasing light is 80 mw; erasing time is 3 s; the density of the erasing power is 2.18 mJ/mm2 .)
Y. Chen et al. / Optical Materials 26 (2004) 75–77
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3.2.2. The spatial resolution of fulgide-PMMA film Fig. 5 represents spatial resolution of fulgide-PMMA film for holographic recording. With a writing angle hw ¼ 30, holographic recording in fulgide-PMMA film gives a grating with N ¼ 1680 lines/mm.
4. Conclusion
Fig. 4. Dependence of the 1st-order diffraction efficiency on the exposure.
The photochromic properties of fulgide doped in PMMA are investigated and the closed form presents absorption band at 626 nm upon irradiation at 373 nm. Fatigue resistance of fulgide-PMMA film is performed by He–Ne laser and it shows the reflectivity is not markedly changed after 450 cycles of writing–erasing. Fulgide-PMMA used as holographic recording material is demonstrated. With a writing angle hw ¼ 30, holographic recording on fulgide-PMMA film, gives a grating with N ¼ 1680 lines/mm. The optimal exposure of 1047 mJ/cm2 and the first order diffraction efficiency g ¼ 2:26% with 10 lm thickness film are obtained.
Fig. 5. Interference fringes recorded on the fulgide-PMMA film (10 lm/div).
Acknowledgements light and erasing one, respectively. It is found that the reflectivity is not markedly changed after 450 cycles of writing–erasing and it indicates no photodegradation is detected after 450 writing–erasing cycles. 3.2. Holographic recording 3.2.1. The first order diffraction efficiency of fulgidePMMA film Holographic recording of a fulgide-PMMA film (thickness 10 lm) is investigated. The diffraction efficiency and the exposure energy are defined as the follow formula, respectively: g ¼ IS =IC ;
Exposure ¼ ðIO þ IR þ IC Þ t:
As shown in Fig. 4, the first order diffraction efficiency increased fast at beginning till the maximum value is obtained (g ¼ 2:26%) with an exposure of 1047 mJ/cm2 . It is known that the value of diffraction efficiency depended on the properties of material and other conditions such as the concentration of compound, the thickness of polymer film and intensity of writing beam.
The work was supported by National Science Foundation of China (no. 60277001 and no. 60337020) and National Principal Research Project ‘‘973’’ (G 1999033005).
References [1] V.P. Pharm, G. Manivannan, R.V. Lessard, Opt. Mater. 4 (1995) 467. [2] T. Weitzel, U. Wild, M. Amlung, H. Durr, M. Irie, Mol. Cryst. Liq. Crist. 344 (2000) 191. [3] V.V. Mogilny, Y.V. Gritsai, SPIE Proc. 340 (1998) 100. [4] T.H. Chao, H. Zhou, G. Reyes, SPIE Proc. 3864 (1999) 181. [5] Y. Yokoyama, Chem. Rev. 100 (2000) 1717. [6] M. Irie, Chem. Rev. 100 (2000) 1685. [7] S. Kawata, Y. Kawata, Chem. Rev. 100 (2000) 1777. [8] B.P. Munday, M.G. Ellerd, Name Reactions and Reagents in Organic Synthesis, John Wiley and Sons, New York, 1988. [9] H.G. Heller, IEE Proc. 130 (1983) 209. [10] M. Seibold, H. Port, K. Gustav, Chem. Phys. Lett. 314 (1999) 65. [11] F. Matsui, H. Taniquchi, Y. Yokoyama, K. Sugiyama, Y. Kurita, Chem. Lett. (1994) 1869. [12] K.D. Belfield, Y. Liu, R.A. Negres, M. Fan, G. Pan, D.J. Hagan, F.E. Hernandez, Chem. Mater. 14 (2002) 3663.