Silicon nitride PIC beam formers for light sheet fluorescent microscopy

Abstract: Light sheet fluorescence microscopy (LSFM) has transformed the way we visualize biological tissues in three dimensions, offering high-resolution imaging while minimizing photo-induced damage to the samples. Recent breakthroughs in tissue-clearing methods have further improved LSFM's capabilities, making it possible to study larger, intact samples in unprecedented detail. To overcome limitations like shallow penetration and light diffraction in traditional LSFM setups, advanced beam shaping with devices such as spatial light modulators and digital micromirror arrays has been utilized. These improve the resolution and the extent of tissues that can be imaged. Advances such as Bessel-beam-based LSFM and lattice light sheet microscopy increase the field of view that can be imaged with low background noise, but often require complex and bulky equipment. Addressing these complexities, a new approach builds on silicon nitride photonic integrated circuits to create a structured light sheet in a very compact device. This system incorporates beam-steering based on wavelength control in a limited tuning range and enables the generation of light sheets with optimized characteristics in regard to thickness and diffraction-length limited penetration depth. Simulations include extensive fabrication tolerance analysis that confirm the practicability of the approach, that can be straightforwardly extended to dual wavelength excitation. This compact, chip-based LSFM system could make high-quality imaging more accessible and transform biomedical instrumentation.