In support of NASA’s Goddard Space Flight Center (Greenbelt, MD) and the European Space Agency’s Laser Interferometer Space Antenna (LISA) mission to measure gravitational waves in space, Avo Photonics (Horsham, PA) is producing over 20 next-generation laser seed sources to demonstrate its design efficacy, manufacturing processes, and laser system ruggedness.
The development comes only five years after the ground-based observatory, LIGO, made its first monumental detection of gravitational waves. The LISA observations will be made while in orbit around the sun. Three satellites will form a triangular interferometer consisting of 2.5 million km arms. With launch set for the mid-2030s, the arduous path of iterative design, material selection, assembly, test, and qualifying processes is underway. Rigorous requirements must be met to ensure the lasers’ necessary performance and ruggedness during ground-based testing, launch, and throughout their 10+ year life in orbit.
In addition to meeting specific satellite needs, Avo Photonics is building what it says will be the “quietest” laser oscillator in the world to serve as the core light source for the interferometric system. The configuration is based on a nonplanar ring oscillator where the facets of the Nd:YAG gain crystal serve as the reflecting surfaces of the cavity, eliminating the need and potential misalignment of external discrete mirrors. The monolithic design, which outputs 200 mW, offers stabilized frequency noise less than 103Hz/Hz for frequencies as low 10-4Hz, and less than 5 Hz/Hz at frequencies above 104Hz. The output from these lasers are each amplified to 2 W as part of NASA’s complete optical system residing on each satellite.