Laser amplifiers with a wide bandwidth require special crystals that are particularly short and thin. Efficient amplifiers, on the other hand, require especially long crystals. Connecting several short crystals in series is one possible way to combine both. It is already being pursued in research. The key is to ensure that the pulses from the pump laser and the signal laser remain synchronized.

New multipass concept

Researchers have now solved this problem with a new multipass procedure. Instead of using a single long crystal or many short crystals, they use a single short crystal and repeatedly run the light pulses through this crystal in their optical parametric amplifier.