  Photonic components responsive to external optical stimuli are attracting
increasing interest, because their properties can be manipulated by light with
fast switching times, high spatial definition, and potentially remote control.
These aspects can be further enhanced by novel architectures, which have been
recently enabled by the availability of 3D printing and additive manufacturing
technologies. However, current methods are still limited to passive optical
materials, whereas photo-responsive materials would require the development of
3D printing techniques able to preserve the optical properties of photoactive
compounds and to achieve high spatial resolution to precisely control the
propagation of light. Also, optical losses in 3D printed materials are an issue
to be addressed. Here we report on advanced additive manufacturing
technologies, specifically designed to embed photo-responsive compounds in 3D
optical devices. The properties of 3D printed devices can be controlled by
external UV and visible light beams, with characteristic switching times in the
range 1-10 s.
