부산대학교 도서관

Transportable ultrastable lasers (TUL) are the key parts of transportable optical clocks. In the previous works, TUL were based on transportable optical cavities with lengths of about 10 cm, which limited the stability of the TUL to middle term of 10 - 16 . In this work, we designed two transportable cavities with lengths of 30 cm and built two TULs with frequency stabilities close to the thermal noise limit of the cavities. The cavities are mounted by squeezing with slim posts on symmetric planes. The mounting method guarantees that the cavities are robust, transportable, and at low vibration sensitivities of < 5 × 10 - 10 / g . The most probable linewidth of the beating between the two lasers is 0.14 Hz. The minimal instability of the beating frequency is 2.0 × 10 - 16 , which happens at 0.5 s averaging time, and increases slowly to 3.2 × 10 - 16 at the averaging time of 100 s. This result is more than 2 times better than previous reported TUL. The design of the cavities may promote the research of transportable optical clock to the level of small coefficient of 10 - 18 . [ABSTRACT FROM AUTHOR]