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-Conjugated organic molecules are known for their large and fast optical
nonlinearities as well as their versatility and compatibility in molecular
design strategy. The different effects produced by the nonlinear optical
absorption and nonlinear refraction exhibited by these materials have lead
to several important applications like optical limitin...
Contexts in source publication
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... ideal optical limiter has a linear transmittance at low input intensities, but above the threshold intensity its transmittance becomes constant [23]. The ideal behavior of such a device is shown in figure 1. 3. It has been demonstrated that optical limiting can be used for pulse shaping and shaping and smoothing and pulse compression. ...
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... mirror image of the absorption band displaced towards lower wave numbers by reflection at the wave number of the purely electronic transition. This condition exist because the transition start from the vibrational ground state of the first excited electronic state S 1 and end in vibrationally excited sublevels of the electronic ground state S 0. Fig. 1.5 Energy level structure of a dye molecule. S n are singlet states, T n are triplet states. Solid arrows represent radiative processes; dashed line denote nonradiative ...
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... is a simple, sensitive single beam method that uses the effect of beam distortion induced by the nonlinear interaction between the incident beam and the nonlinear medium. The schematic diagram of z-scan experiment is shown in Fig.2.1. The excitation source used for the present study was a 10 mW CW He-Ne laser operating at 632.8 nm. ...
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... large induced NLO properties of AB 10B dye-doped solid (DDS) films under cw excitation at 632 nm may primarily be attributed to the glassy, nanoclustered structure of these samples. Here, we also ascribe the prolonged durability exhibited by these DDS films, to the glassy nanostructure formed by the entanglement of comparatively smaller dye molecules in the microdomains between the relatively larger islands of the host polymer, PVA (See the AFM micrographs of pure PVA solid film shown in figure 4B.12). Thin film growth, in general, is influenced by the structure and characteristics of both the host and the substrate material. ...
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... linear absorption spectra of AB 10B-PVA films for three different concentrations of the dye molecule are shown in Fig.4B.1. The molecular structure of AB 10B is ahown in fig.4A.2. ...
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... open aperture z-scan data of AB10B solid film (conc.6.49x10 -4 M) at an incident peak intensity of 2.64 GW/cm 2 is depicted in Fig.4C.1. At the focal point the beam intensity is a maximum and the sample transmittance is minimum, indicating that the sample exhibits positive nonlinear absorption. ...
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... a 2PA process, the intensity dependent absorption coefficient α (I) of the sample is given by [14] (1) where is the intensity-independent coefficient of linear absorption and is the two-photon absorption coefficient. The theoretical fit (doted line) in Fig.4C.1, simulated using equation (1) appeared to be inconsistent with the experimental data, which ruled out the possibility of 2PA. An attempt to fit the experimental data with ESA theory [15] also resulted in an inconsistency, which eliminates the role of ESA in the observed nonlinear absorption. ...
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... dependence of concentration of the dye content on the nonlinear absorption behaviour of AF-PVA films at an incident intensity of 2.641 GW/cm 2 is presented in figure 6.10. Optical limiting graphs were drawn from the open aperture Z-scan data, plotting input fluence versus normalized transmission (Fig. 6.11: a-c.). The curves thus obtained depict excellent limiting effect resulting from a possible two-photon absorption process, as already discussed, occuring in the dye-polymer films on 532nm, nanosecond laser light excitation. ...
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... dye-polymer films, as studied using the standard Z-scan technique, under both cw as well as pulsed excitation, were very high and measured upto the highest reported for various NLO materials including that for Rhodamine 6G under similar conditions. The optical micrographs of the various dye-doped films fabricated for this study are displayed in Fig.1a to 1d. The photographs of these solid film samples obtained using a digital camera are also furnished (Fig. ...
