Abstract

The nonlinearity characteristics of a number of $\mathrm{Li}\mathrm{Ta}{\mathrm{O}}_3$ pyroelectric detectors were experimentally investigated using the National Physical Laboratory (NPL) detector linearity characterization facility. All the detectors examined were shown to exhibit a superlinear response, i.e., the responsivity of the detectors increases as the incident radiant power increases. The temperature coefficient of response of some of these $\mathrm{Li}\mathrm{Ta}{\mathrm{O}}_3$ pyroelectric detectors was measured and found to be approximately $+0.2\%°{\mathrm{C}}^{-1}$. The superlinear behavior of the $\mathrm{Li}\mathrm{Ta}{\mathrm{O}}_3$ pyroelectric detectors was attributed to the positive temperature coefficient of response values of these detectors. Moreover, the linearity factor of gold-black-coated $\mathrm{Li}\mathrm{Ta}{\mathrm{O}}_3$ pyroelectric detectors was shown to exhibit a dependency on the area of the spot illuminating the active area of the detector, i.e., on the incident irradiance. Possible reasons for the observed behavior are proposed and discussed. Some variations in the slopes of the plots of the linearity factor versus irradiance for different areas being illuminated have been assigned to the poor spatial uniformity of response of these detectors.

© 2008 Optical Society of America

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