Precise calibration of zero-crossing temperature and drift of an ultralow expansion cavity with a clock transition spectrum

Liu Hui^{1, 2, 3}, Jiang Kun-Liang^{1, 2, 3}, Wang Jin-Qi^{1, 2, 3}, Xiong Zhuan-Xian^{1, 2}, He Ling-Xiang^{1, 2,}, Lü Bao-Long^{1, 2}

(color online) Measurements at different controlled temperatures along 30–35 °C in the cases with (a) an optical frequency comb and (b) clock transition spectra. The red line is quadratic fitting of the experimental data, from which the zero-crossing temperature is derived.