Schematic view of the final gas sensing microsystem based on low-cost polymer microresonator. Credit: Qingyue Li et al.
Recent research from the University of Toulouse in France has shown that by manipulating 2-photon-polymerization 3D printing a low-cost vertical cavity surface emitting laser could be produced in only a few minutes. By optimizing the fabrication and lens design, sufficient surface quality and focal length were achieved.
In the study, published in the Journal of Optical Microsystems, the researchers aimed to create a compact optical microsystem to be used for the detection of ammonia gas. The researchers opted for a vertical cavity surface emitting laser, or VCSEL, for its compact size and tunability by adjusting the operating current. Despite its compact size, the beam divergence of the VCSEL chip is too large for most applications in optical microsystems.
To remedy this, the researchers utilized 2-photon-polymerization 3D printing to fabricate a microlens. With a single-step fabrication process and a write time of just 5 minutes, the fabrication process represents an economical way to rapidly produce lenses. By optimizing the lens design and fabrication methodology, the researchers were able to optimize the lens to a beam spot size of only 55µm, well below the 100µm threshold needed for optimal detection area coupling.
The research paves the way for optimization of laser chips to be used for optical sensing systems. They intend to further their work by optimizing the final device for optical gas sensing applications. They also intend to further explore the application of 3D femtosecond laser printing in VCSEL chip applications as well as other optical microsystem applications.