Structured illumination generation with an integrated optical chip.

Structured illumination is widely and increasingly used in fluorescence microscopy for super-resolution imaging. We present an integrated optical device able to generate and spatially translate a pattern of structured light, suitable for SIM microscopy. The miniaturized chip incorporates optical waveguides and directional couplers, manufactured with femtosecond laser micromachining, used to split a single input laser into multiple coherent light sources, balanced in optical power. The relative phases of the waveguides are controlled by a set of thermal phase-shifters, placed on top of the same device so that the SIM pattern is generated by interference of coherent beams. By exploiting the temporal phase control of the waveguides, we can spatially shift the illumination pattern over the field of view of the microscope. In this way, it is possible to acquire the multiple phase images required for SIM reconstruction, without the need of further optical elements. We show the validation of the chip, demonstrating the acquisition of super-resolved images in possible configurations of use such as in a commercially available inverted microscope or in a custom-made fluidic chip.