There is a developing interest in convenient gas sensors from both ecological and wellbeing sciences clients as well as industry. Planar micro-resonators, in particular, are good candidates for these applications because they combine high sensitivity with a small footprint.
The detection guideline of these directed wave sensors depends on a variety of ghastly reactions within the sight of the objective particles. The laser source to be utilized for testing such ghastly movements ought to produce a solitary mode and a polarization-stable bar and ought to be frightfully tunable over essentially a couple of nanometers.
A group of specialists based at the College of Toulouse in France pointed toward manufacturing such a conservative optical microsystem for smelling salt gas recognition utilizing a close infrared single-mode laser diode source, in particular an upward cavity surface radiating laser, or VCSEL.
By simply adjusting the operating current, this kind of semiconductor laser diode, which is very small, can be spectrally tuned within a few nanometers. Besides, the particular VCSEL chip utilized in their work incorporates a grinding help carved at the surface, which guarantees a decent polarization soundness of the radiated shaft. Be that as it may, despite the fact that it is more modest than for a Drove or for a standard edge-discharging laser diode, the pillar uniqueness of this VCSEL chip is excessively huge for most reasonable purposes in optical microsystems.
In this examination, the spot size at the pointed working distance (2 mm) is, to be sure, bigger than 250 m.To ensure the best possible coupling with the detection area, it should be less than 100 millimeters in diameter. Polarization-stable single-mode VCSEL chips with a diminished disparity are tragically not yet financially accessible. Finding a precise method to directly integrate a collimation micro lens on a 200x200x150 m3 VCSEL chip already mounted on a printed circuit board presents a challenge.
In this work, distributed in the Diary of Optical Microsystems, the scientists show the way that 2-photon polymerization three-dimensional printing can be taken advantage of to create such a micro lens in a single step and with a composition time of just 5 minutes. To this point, they streamlined the focal point plan and creation conditions to get an adequate surface quality along with a reasonable central length.
The shaft uniqueness of the laser chip could be diminished from 14.4° to 3°, relating to a pillar spot size a good ways off of 2 mm of just 55 m.They likewise concentrated tentatively and hypothetically on the impacts of focal point expansion on the gadget’s ghastly properties and proposed another plan to stay away from a decrease in the tuning range.
The work done by the group paves the way for the creation of optimized laser chips that can be directly integrated into portable optical sensing systems and demonstrates the interest in 2-photon polymerization 3-D printing as a fast and accurate method for VCSEL collimation at a post-mounting stage.
More information: Qingyue Li et al, Direct 3D-printing of microlens on single mode polarization-stable VCSEL chip for miniaturized optical spectroscopy, Journal of Optical Microsystems (2023). DOI: 10.1117/1.JOM.3.3.033501
