Enhancement of the frequency conversion film imaging effect based on a cascade material fusion method

Frequency conversion imaging technology can provide an effective way for infrared detection against the limitations of conventional infrared detectors, such as expense and cooling requirements, but the converted luminescence intensity of frequency conversion materials limits the application of this technology. In this paper, a cascade material (CM) fusion method is proposed to improve the conversion luminous intensity and thus enhance the frequency conversion imaging effect at 1550 nm near infrared (NIR) excitation. First, we derived from the energy level transition mechanism of CM that the CM fusion method can achieve three excitations of substrate materials (SMs). It can improve the conversion luminescence intensity of SM in CM. Then, we experimentally prepared CM and SM films and simultaneously measured the frequency conversion imaging effect of the two films at 1550 nm NIR excitation. It was found that the weight ratio of doped material (DM) to SM affects the imaging enhancement of CM films. Therefore, we compared the imaging grayscale value intensity of CM films with different weight ratios under the same detection conditions. Finally, it was concluded that the best enhancement of frequency conversion imaging was achieved with a DM to SM weight ratio of 0.25 for this mechanism. The enhancement was about 3.11 times compared to SM films.