Femtosecond laser multibeam parallel processing for variable focal-length optofluidic chips

Optofluidic chips are frequently utilized in applications such as biological observation, chemical detection, dynamic displays, imaging, holography, and sensing. Yet, developing continuously zoomable technology has been challenging in the production of optical devices. Using a spatial light modulator to shape a femtosecond laser to achieve multibeam parallel pulse punching, we propose an easy-to-fabricate, stable, and reliable tuning technique in this Letter. We then propose the addition of a liquid medium with a continuously variable refractive index to achieve controllable zooming without changing the position and morphology of the microlens. By pumping various concentrations of the liquid medium into the optofluidic chip, continuous tunability of the device was experimentally verified.