Graphene materials have attracted interest in the field of optical limiting because of their outstanding linear and nonlinear optical (NLO) properties. However, poor solubility and agglomeration have limited the practical applications of these materials. Here, hydrophilic graphene oxide materials, including graphene oxide nanosheets (GONSs) and graphene oxide nanoribbons (GONRs) are synthesized. Using a facile sol-gel process, GONSs and GONRs are introduced into a methyltriethoxysilane modified silicate (Ormosil) glass matrix. NLO and optical limiting (OL) properties are investigated using a nanosecond Zscan technique at 532 nm. Large OL effects of Ormosil hybrid glasses are revealed, whose optical limiting thresholds (F th ¼ $0.03 J cm À2 ) surpass those of corresponding suspensions by a factor of 5-20.We deduce that this behavior is mostly attributed to the combined mechanisms of nonlinear scattering and nonlinear absorption. The hybrid glasses are free of damage after hundreds of continuous laser shots with an energy of 800 mJ. These results indicate that Ormosil hybrid glasses doped with graphene oxide materials could be promising candidates for optical limiters.
The nonlinear optical properties of nonzero-bandgap graphene materials and the corresponding hybrid glasses were strongly affected by the laser duration.
This paper mainly deals with the problem of detecting and identifying target in close range, the performance of which will be effected by the radiometer's parameters and target's characteristics. According to the relationship between the range equation of the Passive Millimeter Wave (PMMW) and these parameters, we present a convenient statistical method based on PMMW image detection to solve the inherent problem by statistical radiometer parameters, which can be achieved by the W band radiometer experimental data. Finally, we validate the method by simulation and experiment. The results show that the method is convenient for detecting and identifying target in close range.
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