KTH: Optical fiber 3D-printed glass sensors, 1,000 times smaller than a grain of sand

Researchers at KTH Royal Institute of Technology in Stockholm, reporting in the journal ACS Nano (3D Printing of Glass Micro-Optics with Subwavelength Features on Optical Fiber Tips), have found that integrating silica glass optical devices with optical fibers can lead to various advancements, such as more sensitive remote sensors for environment and healthcare purposes.

The techniques they have developed could also have practical applications in the production of pharmaceuticals and chemicals.

New advancements

According to Professor Kristinn Gylfason, this method overcomes previous difficulties in shaping optical fiber tips with silica glass, as it eliminates the need for high-temperature treatments that can damage temperature-sensitive fiber coatings.

Unlike other methods, this process begins with a base material that does not contain carbon, thus avoiding the need for high temperatures to make the glass structure transparent.

In a study led by Lee-Lun Lai, a silica glass sensor was printed and found to be more robust than a standard plastic-based sensor after multiple measurements. Lai explains that they successfully created a glass refractive index sensor on the fiber tip that allows them to measure the concentration of organic solvents.

We demonstrated a glass refractive index sensor integrated onto the fiber tip that allowed us to measure the concentration of organic solvents. This measurement is challenging for polymer-based sensors due to the corrosiveness of the solvents

Lee-Lun Lai

Co-author Po-Han Huang adds that these structures are so small that 1,000 of them could fit on the surface of a grain of sand, which is similar to the size of sensors currently in use.

These structures are so small you could fit 1,000 of them on the surface of a grain of sand, which is about the size of sensors being used today

Po-Han Huang

The researchers also demonstrated a printing technique for nanogratings, which are ultra-small patterns on surfaces that can manipulate light in precise ways and have potential applications in quantum communication.

Gylfason notes that the ability to 3D print various glass structures directly onto fiber tips opens up new possibilities in photonics. “By combining 3D printing and photonics, this research has far-reaching implications, with potential uses in microfluidic devices, MEMS accelerometers, and fiber-integrated quantum emitters,” he says.