Towards on-chip high index contrast rare-earth-doped potassium double tungstate amplifiers

The monoclinic double tungstate crystals are good candidates as host materials for rare-earth ions. Thanks to their crystalline nature, clustering of doping ions is avoided. High concentrations of active ions can therefore be achieved, which, together with the large absorption and emission cross sections of the active ions in these materials, leads to compact and efficient on-chip amplifiers and lasers. However, the fabrication of integrated on-chip waveguide amplifiers and lasers integrated with dielectrics or semiconductors is challenging. In this work, we will present our current efforts on the development of on-chip high index contrast waveguide amplifiers in rare-earth ion doped potassium double tungstates.