Structure optimization of azobenzene oligomers for holography

Ozols, Andris; Reinfelde, M.; Kampars, Valdis; Kokars, Valdis

doi:10.1002/pssc.200460261

Cited by 5 publications

(11 citation statements)

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“…One can see from Table 1 that the best results have been obtained for the samples 2 and 7 with α-nitronaphtylazobenzene and phenyl-α-azo-β-chloro-antraquinone chromophores, respectively in HM matrix. This is in contrast to our previous results [3] with simple chromophores when Tl matrix was more efficient. The Tl matrix is stiffer than the HM one.…”

Section: Resultscontrasting

confidence: 99%

“…This means a purely phase recording due to the photoinduced refractive index changes since such fast (in minutes) transient DE changes are unlikely for photoinduced thickness changes with mass transfer. The photoinduced refractive index changes, most probably, are caused by the photoorientation of chromophore groups [1][2][3]. This conclusion is supported also by the results presented here.…”

Section: Resultssupporting

confidence: 90%

“…Therefore, the photoorientation of larger and more complex chromophore groups in side-chains is easier in more elastic HM matrix. However, the holographic recording in Tl matrix with simpler chromophore groups was more efficient [3]. Surprisingly, no correlation is found between recording efficiency and spectroscopic data (λ max , D max ).…”

Section: Resultsmentioning

confidence: 91%

“…The lifetime of the recorded HG varied from about 30 minutes (type II ABO) to several hours ( type I ABO [3]). During the exposure there were no observable optical transmittance changes at 633 nm.…”

Section: Resultsmentioning

confidence: 99%

“…1 Introduction Organic materials have been extensively studied as recording materials for scalar and vector holography [1, 2] because they allow for wider tailoring of properties than inorganic materials. Azocompounds are among the most efficient holographic recording materials, which we have studied, also in previous papers [3]. In this paper we report on further studies of azobenzene oligomers (ABO), for holography in the red spectral region, which is of special theoretical and practical interest.…”

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confidence: 83%

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Holographic properties of azobenzene oligomers with differently bonded chromophore groups

Ozols

Saharov

Kampars

et al. 2007

Phys. Status Solidi (c)

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PACS 42.40. Lx, 42.70.Jk, 42.70.Ln Holographic properties of two types (I and II, specified in the text) of azobenzene oligomers (ABO) have been experimentally studied in the spectral region of low absorption at 633 nm. In the case of type I ABO the chromophore groups were covalently bonded to either tolyl-polyurethane or hexamethylenepolyurethane matrix. In the case of type II ABO azobenzene chromophores were dispersed in polystyrene matrix, and their concentration was varied from 0.005 to 0.200 mol/l. Samples were in the form of 10 µm thick films. In both cases the diffraction efficiency exposure time dependences were measured for the holographic grating period of 2 µm at 633 nm. The diffraction efficiency of more than 2% and the specific recording energy down to 30 -60 J/(cm 2 %) were achieved in both cases. In the case of type I ABO the best results were achieved with 4-nitronaphtylazobenzene chromophore groups in hexamethylenepolyurethane matrix. The chromophore concentration threshold within 0.01 -0.04 mol/l range, the holographic efficiency growth with chromophore concentration and the photosensitization effect were found in the case of type II ABO. 1 Introduction Organic materials have been extensively studied as recording materials for scalar and vector holography [1, 2] because they allow for wider tailoring of properties than inorganic materials. Azocompounds are among the most efficient holographic recording materials, which we have studied, also in previous papers [3]. In this paper we report on further studies of azobenzene oligomers (ABO), for holography in the red spectral region, which is of special theoretical and practical interest. First, the unclear physical mechanism [4] that enables recording in the spectral region with very low absorption is of large interest. Second, the hologram recording in this region allows one to obtain higher diffraction efficiency (DE) and to use cheaper lasers. Two groups of materials have been studied: ABO with covalently bonded chromophore groups (type I ABO) and ABO with dispersed (without the covalent bondings, type II ABO) ones. The matrices were also varied. The polyurethane structure was modified by tolyl (Tl) or hexamethylene (HM) in the case of type I ABO (Fig. 1). (These matrices we further designate as Tl and HM matrices.) Polystyrene matrix was used in the case of type II ABO. Each type of samples has its advantages and disadvantages. Oligomers with chromophore groups covalently bonded to the matrix exhibit higher DE and photosensivity yet the synthesis standardization is difficult. On the contrary, ABO with dispersed chromophore groups until now have exhibited lower holographic efficiency but their synthesis is much easier and more predictable. In this work we show that their efficiency can be comparable to that of the first group.

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Section: Resultscontrasting

confidence: 99%

Section: Resultssupporting

confidence: 90%

Section: Resultsmentioning

confidence: 91%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 83%

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