*Article* **Temperature-Modulated Pyroelectricity Measurements of a Thin Ferroelectric Crystal with In-Plane Polarization and the Thermal Analysis Based on One-Dimensional Layer Models**

**Kaoru Yamamoto 1,\*, Ayumi Kawasaki 1, Takumi Chinen <sup>1</sup> and Kayo Ryugo 1,2**


**Abstract:** A temperature-modulated pyroelectricity measurement system for a small single crystal is developed and applied to standard sample measurements performed on a thin single crystal of lithium niobate. The modulation measurement is based on the AC technique, in which the temperature of the sample is periodically oscillated, and the synchronized pyroelectric signal is extracted using a lock-in amplifier. Temperature modulation is applied by irradiating periodic light on the sample placed in the heat exchange gas. To apply this technique to the transparent reference sample, a commercially available black resin is coated on the sample's surface to absorb the light energy and transmits it to the specimen. The experimental results are analyzed using a two-layer heat transfer model to verify the effect of the light-absorbing layer as well as the radiative temperature modulation system.

**Keywords:** pyroelectricity; temperature modulation; molecular ferroelectrics; radiative temperature control; thermal diffusion model; lithium niobate
