8 x 10-17 fractional laser frequency instability with a long room-temperature cavity

We present a laser system based on a 48 cm long optical glass resonator. The large size requires a sophisticated thermal control and optimized mounting design. A self-balancing mounting was essential to reliably reach sensitivities to acceleration of below Delta nu/nu < 2 x 10(-10)/g in all directions. Furthermore, fiber noise cancellations from a common reference point near the laser diode to the cavity mirror and to additional user points (Sr clock and frequency comb) are implemented. Through comparison with other cavity-stabilized lasers and with a strontium lattice clock, instability of below 1 x 10(-16) at averaging times from 1 to 1000 s is revealed. (C) 2015 Optical Society of America