3. Volume-integrated optical systems

Refractive index modification has repeatedly been presented as the building block for the manufacture of optical functions, which we have termed the field of 3D photonics. These functions can be multi-faceted, combining optical, electrical and mechanical characteristics to present complex optical, opto-mechanical or electro-optical responses. Laser scanning techniques similar to those presented above can leverage this elementary index change brick to produce complex fabrications in the volume of the materials. This manufacturing process gives these functions intrinsic phase stability. Three-dimensional geometries enable flexible, high-performance optical designs. Passive and active systems can thus be obtained, notably by integrating engineering of the material where the modifications are produced (dopants, particles, etc.). Numerous research teams around the world are working on integrated...