Nanoscale Glass Structures, 3D-Printed on the Tip of an Optical Fiber, Offer Robust Sensing

A thousand times smaller than a grain of sand, these glass sensors can withstand conditions current device cannot.

Gareth Halfacree
29 days ago3D Printing / Sensors

A team of researchers from the KTH Royal Institute of Technology in Sweden have come up with a way to 3D-print optical devices straight onto the tops of optical fibers — creating glass sensors that are more sensitive and more robust than their rivals and showing potential for quantum optical systems.

"We demonstrated a glass refractive index sensor integrated onto the fiber tip that allowed us to measure the concentration of organic solvents," explains lead author Lee-Lun Lai of the team's work, which is hoped could provide better remote sensors for everything from environmental monitoring to healthcare and chemical production. "This measurement is challenging for polymer-based sensors due to the corrosiveness of the solvents."

The team's approach requires a base material which lacks carbon — avoiding the need to heat it to extreme temperatures in order to improve its optical transparency, a process that damages the coatings on optical fibers. This material is used to print silica glass optical devices straight onto the tip of an optical fiber — and at a tiny scale.

"These structures are so small you could fit 1,000 of them on the surface of a grain of sand," explains co-author Po-Han Huang of the printed devices, which can be of arbitrary shape and size, "which is about the size of sensors being used today." These devices can be printed as either solid devices in what the researchers call "uniform mode" or as self-organized sub-wavelength gratings in "nanograting mode" — the latter showing real potential for quantum photonics efforts.

"By bridging the gap between 3D printing and photonics," claims professor Kristinn Gylfason, co-correpsonding author on the team's paper, "the implications of this research are far-reaching, with potential applications in microfluidic devices, MEMS accelerometers and fiber-integrated quantum emitters."

The team's work has been published in the journal ACS Nano under open-access terms, while the researchers have applied for a patent on the technique.

Main article image courtesy of David Callahan.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
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