946-nm Nd:YAG digital-locked laser at 1.1times10⁻¹⁶ in 1 s and transfer-locked to a cryogenic silicon cavity

We present a Nd:YAG ultra-stable laser system operating at 946 nm and demonstrate a fractional frequency instability of $1.1\times10^{-16}$ at 1 s by pre-stabilizing it to a 30 cm-long ULE cavity at room temperature. All key analog components have been replaced by FPGA-based digital electronics. To reach an instability below the $10^{-16}$ level, we transfer the stability of a 1542 nm laser stabilized to a cryogenic silicon cavity exhibiting a fractional frequency instability of $4\times10^{-17}$ at 1 s to the laser at 946 nm.