MPBC 100W CW 1178nm, single mode, single-frequency, linearly polarized Raman fiber amplifier (RFA) powers ESO’s New 63W CW experimental guide star laser.

This laser is to form part of the CaNaPy Laser Guide Star Adaptive Optics facility, set to be installed at the European Space Agency’s (ESA) Optical Ground Station in Tenerife, Spain, in the frame of the joint ESO-ESA R&D collaborative efforts.

Powered by the MPBC 100W CW 1178nm, single-mode, single frequency, linearly polarized Raman fiber amplifier (RFA), first announced by the company at the SPIE Astronomical Telescopes + Instrumentation Conference in 2018, the new experimental laser provides an unprecedented level of power, almost three times that of the current generation SodiumStar manufactured by MPB and Toptica Photonics and deployed at ESO’s Very Large Telescope as well as observatories worldwide.

MPBC is a Licensee of the ESO Fiber Raman Amplifier Technology developed and transferred by ESO. The MPBC PM RFA is an adaptation of the narrow-band RFA technology developed by ESO. The key challenge in amplifying a narrow-band signal to such high-power levels in an RFA is overcoming the limitation imposed by Stimulated Brillouin Scattering (SBS), a non-linear optical effect.

The MPBC 100W CW 1178nm unit uses a two-stage polarization-maintaining (PM) RFA counter-pumped by a PM 1120-nm fiber laser to amplify a linearly-polarized 15-mW narrow-linewidth 1178-nm seed laser. Efficient suppression of stimulated Brillouin scattering (SBS) pushes the SBS threshold above 100W. Through careful selection of Raman fiber types and lengths, the Raman conversion efficiency is maximized thereby mitigating thermal loads on critical optical components, thus maintaining long-term reliability.

‍‍This state-of-the-art development facilitates new Laser guide star (LGS) applications including the implementation of LGS adaptive optics systems in satellite ground stations for optical feeder links. While the next generation of satellite constellations provide unprecedented capacity through the use of optical inter-satellite links, there is still a capacity bottleneck at the RF feeder links from satellite to ground stations, which are a magnitude slower in moving data.  In order to move to all optical feeder links, there is a challenge to overcome the distortion associated with atmospheric turbulence.  LGS adaptive optics systems are a key enabling technology to help solve this beam wander problem for ground to space optical systems.

The new 100W RFA complements MPB Communications' multiple activities in satellite optical communications, which includes the development and supply of very high-power amplifiers for ground-to-space communications, as well as the supply of space-based optical amplifiers for inter-satellite communications for deployment in next-generation optical satellite constellations.