Frequency stabilized laser for length metrology system in Joule Balance

This paper shows a frequency offset-locked laser designed for the length metrology system in the next-generation Joule Balance. This laser integrates most of the components in a limited volume and avoids serious thermal pollution. The frequency stability of this laser is about 4.2×10
^-10
at the sampling rate of 0.1s, which totally meets the demands of length measurement with the relative uncertainty better than 1×10
^-8
in Joule Balance.