Rapid Prototyping of a Micro-Scale Spectroscopic System by Two-Photon Direct Laser Writing

The development of two-photon 3D lithographic technologies has enabled the fabrication of 3D optics at sub-micron resolution. The freedom allotted by this technology allows for the fabrication of miniaturized complex optical components, such as freeform micro-optics and diffractive optical elements. Additionally, the ability to rapidly prototype these micro-optical components facilitates the development of custom-tailored optical systems for specialized applications. The goal of this work is the construction of a prototype micro-optical system that enables quantitative absorbance spectroscopy for use in the visible and near infrared (VIS/NIR) regions. Employing a combination of optical design software and two-photon direct laser writing (TP-DLW) we seek to demonstrate functionalization of an optical fiber with a miniaturized spectrophotometer, integrable with mobile devices. The methods used to produce this miniaturized optical system facilitates functionalization of chip-on-tip technology, as a low-cost approach for realization of integrated spectrophotometers in applications from quality assurance in the food and drug industries, to spectral tissue sensing in medicine. Presented in this work are the representative results of the performance and integrability of a prototyped micro-spectrophotometer probe at the tip of an optical fiber.