Black holes are exceptionally dense objects with such strong gravitational pull that no particle or electromagnetic radiation can escape from them. A supermassive black hole, nicknamed Sagittarius A* or Sgr A*, occupies the heart of our galaxy, the Milky Way.

Of all the known black holes, Sgr A* appears as the most spread in angular diameter because of the advantageous compromise between its intrinsic size and its distance to the Earth.

However this size is still too small to allow detailed studies with existing instruments.

That is why the GRAVITY consortium has been formed, with the objective of designing a new generation instrument capable of probing the spacetime until the event horizon (the border of the black hole).

The main technical challenges and developments for Le Verre Fluoré in providing IR fiber solutions for the GRAVITY project include:

• Very low birefringence optical fiber
• Fiber optic differential delay line
• Very precise fiber alignment (<1 µm) in a 4-fiber Vgroove
• Polarization rotator