3D in-plane integrated micro reflectors enhancing signal capture in lab on a chip applications

The integration of micro-optics in lab on a chip (LOCs) devices is crucial both for increasing the solid angle of acquisition and reducing the optical losses, aiming at improving the signal-to-noise ratio (SNR). In this work, we present the thriving combination of femtosecond laser irradiation followed by chemical etching (FLICE) technique with CO₂ laser polishing and inkjet printing to fabricate in-plane, 3D off-axis reflectors, featuring ultra-high optical quality (RMS ∼3 nm), fully integrated on fused silica substrates. Such micro-optic elements can be used both in the excitation path, focusing an incoming beam in 3D, and in the acquisition branch, harvesting the optical signal coming from a specific point in space. The flexibility of the manufacturing process allows the realization of micro-optics with several sizes, shapes and their integration with photonic circuits and microfluidic networks.