UV Photonic-Integrated-Circuits-Based Structured Illumination Microscopy With a Field of View Larger than 100\,μ m²

Photonic integrated circuits (PICs) are expected to add practicality and new functionalities in a considerable number of optical applications, including optical microscopy. Here, we present a PIC design allowing a far-field structured UV illumination pattern with a fringe period as low as 370 nm, a fringe visibility of 0.83 over field of views of more than150\,μ m× 200\,μ mand a radiant intensity as large as 0.49 mW. The circuits include single mode waveguides with propagation losses of 3 dB/cm at a wavelengthλ =360\,nm, two diffraction gratings for beam shaping out of the chip plane, a beam splitter and a phase shifter. Using fluorescent gratings with pitches longer or shorter than the wavelength, as control objects, and a collecting lens with a numerical aperture of 0.5, the current PICs enable to highlight experimentally the Moiré pattern at the heart of the optical resolution enhancement and to achieve a doubling of the optical resolution in the direction of the illumination.