Daspb Doped PMMA-MA Polymer Film Report
5. Results & Discussion :
The optical nonlinearity of DASPB doped PMMA-MA polymer film is studied using open aperture and closed aperture Z-scan techniques by means of low power CW laser at different dye-doping concentrations. The open aperture Z-scan study shows that the dye-doped sample shows a considerable amount of saturable absorption property. But at higher input intensity, the two-photon absorption and the reverse saturation absorption properties of the dye in polymer film becomes prominent as shown in Z-scan graph of figure 8. From figure 6, it is seen that the transmission at the focus decreases with increasing sample concentration. At higher concentration, the dye-doped sample shows better nonlinear absorption properties. As shown …show more content…
The optical limiting responses of the low dye concentration films are generally much weaker than those of high concentrated films, and hence high concentrated films exhibit strong optical limiting. This indicates an inverse relationship between the number density of dye molecules in the laser beam with the output clamping level. From the graph, it can be seen that the threshold intensity for optical limiting is inversely proportional to the dye concentration in the PMMA-MA film. The limiting experiment shows that as the concentration increases, both the linear transmittance as well as the output clamping level decreases. The experimentally determined optical limiting saturated output power values are shown in Table 3. The results are comparable to some of the reports of low power optical limiting [41-47]. In the case of optical limiter with aperture, as observed in our experiment and in other published results, it is seen that at the valley positions, the limiter works at very low powers as the self-defocusing effect is enhanced by the thermal effect which is closely related to the absorptive properties of the DASPB dye used. Thus it can be suggested that the best position for a sample, when used for optical limiting based on self-defocusing (type 2) is at the valley point of the Z-scan curve.
Table 6 : Concentration dependence of saturated output power in DASPB dye-doped in PMMA-MA film.
S. No. Dye Concentration (mM) Type 1 Optical Limiting Saturated Output Power (mW) Type 2 Optical Limiting Saturated Output Power
The optical nonlinearity of DASPB doped PMMA-MA polymer film is studied using open aperture and closed aperture Z-scan techniques by means of low power CW laser at different dye-doping concentrations. The open aperture Z-scan study shows that the dye-doped sample shows a considerable amount of saturable absorption property. But at higher input intensity, the two-photon absorption and the reverse saturation absorption properties of the dye in polymer film becomes prominent as shown in Z-scan graph of figure 8. From figure 6, it is seen that the transmission at the focus decreases with increasing sample concentration. At higher concentration, the dye-doped sample shows better nonlinear absorption properties. As shown …show more content…
The optical limiting responses of the low dye concentration films are generally much weaker than those of high concentrated films, and hence high concentrated films exhibit strong optical limiting. This indicates an inverse relationship between the number density of dye molecules in the laser beam with the output clamping level. From the graph, it can be seen that the threshold intensity for optical limiting is inversely proportional to the dye concentration in the PMMA-MA film. The limiting experiment shows that as the concentration increases, both the linear transmittance as well as the output clamping level decreases. The experimentally determined optical limiting saturated output power values are shown in Table 3. The results are comparable to some of the reports of low power optical limiting [41-47]. In the case of optical limiter with aperture, as observed in our experiment and in other published results, it is seen that at the valley positions, the limiter works at very low powers as the self-defocusing effect is enhanced by the thermal effect which is closely related to the absorptive properties of the DASPB dye used. Thus it can be suggested that the best position for a sample, when used for optical limiting based on self-defocusing (type 2) is at the valley point of the Z-scan curve.
Table 6 : Concentration dependence of saturated output power in DASPB dye-doped in PMMA-MA film.
S. No. Dye Concentration (mM) Type 1 Optical Limiting Saturated Output Power (mW) Type 2 Optical Limiting Saturated Output Power