CHARACTERIZING OPTICAL RADIATIVE PROPERTIES IN ADDITIVELY MANUFACTURED MICRO-SCALED POROUS MEDIUM

We use an ultra-high-resolution micro-fabrication of monodisperse porous media using two-photon polymerization (TPP) direct green laser writing maskless technology. By precisely controlling sub-nanosecond laser pulses and nonlinear laser-polymer interactions, TPP generates ultra-narrow, reproducible voxels, enabling sub-micron resolution by achieving feature sizes below the diffraction limit of light without the layer-by-layer limitations of traditional AM methods. We perform 3D printing using an inverted optical microscope of a 20X lens and use process parameters, i.e., the refractive index of photoresist, printing speed, power, and exposure times, tailored to achieve printing precision. Post-printing, we utilize a chemical bath composed of (propane-2-ol:4- methylpentan-2-one) to develop and assess printing quality using SEM images. We then measure the optical radiative properties, of the sample using spectroscopy within the wavelength range of 300nm 800nm. We compare the precision of radiative property measurements with Monte Carlo ray tracing simulations. The results show approximately ~< 5% deviation between the theoretical ground truth and the measurements. Its high-throughput fabrication and minimal material waste, while maintaining radiative properties consistent with theoretical predictions, make it ideal for various engineering applications, including micro-optics, photonics, next-generation solar cells, and metamaterials.