INVESTIGATION ON LITHIUM NIOBATE PYROELECTRIC DETECTOR

Based on the experimental results obtained from both the measurement of material parameters and device responsivity, it is verified that the pyroeleetric responsivity figure of merit of LiNbO3 crystal, Mv is twice as high as that generaly acknowledged value. Furthermore, when the temperature rises, Mv slowly decreases rather than in-creases evidently with temperature as reported in certain literatures. In this paper, the output characteritics of LiNbO3 pyroeleetric detector which is irradiated by the high-power CW CO2 laser has been investigated. The results show that the maximum power density at which the output characteristics of LiNbO3 detector begin to deviate from linear range far exceeds that of LiTaO3 detector under the same conditions. We have carefully measured the intrinsic dielectric loss tgd of LiNbO3 crystal. The value obtained can be used to estimate the detectivity limit of LiNbO3 pyroelectric detector. Detailed analysis proves that, for producing the pyroelectric detector with background limited performance, its figure of merit of LiNbO3 crystal is favorable, and no loss than those of most commonly used materials, such as TGS.