Scientists have created tiny personalized optical devices by applying high-intensity laser beams

3D printing creates objects by adding layers of molten plastic or metal, but this technique is limited to larger sizes. Scientists question how to make tiny devices that cannot be produced using layering, and whether printing directly inside pre-existing three-dimensional materials can be imagined.

A team led by University of Illinois at Urbana-Champaign faculty members Lynford Goddard and Paul Braun has been working together to create a program for this purpose. They use multi-photon lithography to imprint a preexisting permeable material by applying a high-intensity laser beam.

The scientists were able to alter specific regions of the interior and use a technique called sub-surface Controlled Refractive Index through light beam exposure (SCRIBE) to create personalized, tiny optical devices.

Both research teams revealed improvements to the process that allowed them to have greater precision for the final product. ACS Photonics has recently released details of this new program.

A process called SCRIBE utilizes two-photon absorption as a mechanism for multi-photon lithography. According to the scientists, transparent silica is made by oxidizing silicon, which has been etched to contain tiny pores at a microscopic level.

They then filled it with a substance called a photoresist, which can undergo a chemical reaction that changes its optical properties only when it absorbs two photons at once. This phenomenon is rare, unless extremely strong light is used.

Scientists use this technique by focusing laser beams to produce high amplitude in different areas. This allows them to make personalised blueprints of the optical characteristics of matter in three dimensions to "write" the optical composition.

Earlier versions of SCRIBE were limited by poor management of laser intensity. To address this problem, the researchers propose three improvements to the method in their study. Initially, they mapped the density of the photoresist using a two-photon fluorescence imaging mechanism and adjusted the laser intensity required for the desired results.

They also corrected for differences that were particularly pronounced near the writing perimeter by adjusting the position of the material during laser engraving. Eventually, they added a time gap between the laser pulses to reduce the time-dependent effect on the photoresist interaction.

By integrating these three enhancements, scientists can better control their patterned devices and thus more accurately produce ingredients that exhibit greater efficiency.

To demonstrate the adaptability of their technology, they made a 100 x 100 micron optical device that can modify light to create definite color designs, a linear diffraction grating that replicates the configuration and hue of the UIUC logo.

Goddard is a faculty member in the electrical and computer engineering department, while Braun is a faculty member in the materials science and engineering department.

Littlefield and Goddard's graduate students Lawrence Ju, Jingxing Gao and Lonna Edwards, And Dajie Xie, Corey Richards, and Christian Ocier from Braun's team, as well as undergraduate students Haibo Gao and Jonah Messinger, all contributed to the study.

Researchers from UIUC and the University of Illinois at Chicago assisted in the experiment, including but not limited to Jeff Grau, Austin Cyphersmith, Anuj Singhal, and Seyoung An.

The research was funded in part by the UIUC Granger School of Engineering, the National Science Foundation, and the Department of Energy. This work received additional assistance through scholarships awarded by the Ministry of Defense and UIUC.

Source: Laser Net