Phase Stabilized, Frequency Agile Laser System for Gravitational Wave and Dark Matter Detection Using Atom Interferometry (MAGIS-100)

MAGIS-100 is 100-meter atom interferometer currently being built at Fermilab which will leverage modern atom optics techniques to search for oscillations in fundamental constants and time-dependent, equivalence-principle-violating forces which are key signatures of several ultra-light dark matter candidates. In addition, the interferometer can test the coherence limits of spatially separated wave packets and will also serve as a prototype gravitational wave detector in the frequency band between the peak sensitivities of LIGO and LISA. Generation and precise control of meter-separated quantum atomic superpositions within the interferometer requires an agile laser system able to rapidly shift the optical frequency up to a rate of 100 GHz/s while maintaining a phase lock to our static frequency comb. To meet the power requirement of the experiment, two lasers coherently locked must be robust to these rapid frequency shifts. Furthermore, the laser spatial mode is cleaned through fiber coupling and long free space propagation in vacuum. Frequency noise introduced by the fiber is suppressed with a PID lock.