Putting up the Christmas tree
One of the goals of integrated photonics is the miniaturization of components. However, this often comes at a price of reduced flexibility in the choice of available materials and range of applications, since photonic integrated circuits are mostly limited to one material system with specific properties.
On the other hand, optical benches in laboratories provide a maximum of flexibility via optical paths created by mirrors and lenses, where optical materials can simply be inserted.
In order to overcome the limitations of integrated photonics and still keep the advantages in miniaturization, a micro-optical bench is developed on the PolyBoard. With microscopic lenses, called graded-index lenses, optical free-space paths are created on chip, which enable the insertion of materials formerly limited to optical benches in laboratories.
In UNIQORN, this approach is used for the on-chip integration of non-linear optical crystals for the generation of entangled photons. But today on Christmas Eve, we insert very special components.