Development of a Cryogenic Silicon Cavity Stabilized Laser

In this paper, we present the current development status of a cavity stabilized laser at 1550 nm. The expected thermal noise limit of the silicon Fabry-Perot cavity is $3\times 10^{-17}$ at 17 K in terms of fractional frequency instability. We cooled it to its thermal expansion turning point, measured at 18.1 K, with a pulse-tube based cryocooler. Thanks to the thermal filtering and the temperature control of the cavity, the temperature induced fractional frequency instability is below the thermal noise up to 1000 s of integration time. We also discuss the vibration induced limitations, the thermal characterization of the cryocooler and the digital servo implementation and performances.