| Popis: |
One of the main challenges of laser-based gas sensingis the development of sensors delivering simultaneously high sensitivity, selectivity, fast-response time and non-complex design. Mostly, the detection capability of such sensors depends on the interaction path length between the laser light and the measured gas. Hence, long optical paths are highly desired for e.g. low-concentration gas sensing. Our proposal is to use Antiresonant Hollow-Core Fibers (ARHCFs), which filled with the target gas mixture form absorption cells with potentially any length, delivering low-volume, long and versatile optical paths within the sensor configuration. Currently, the ARHCF core is filled with the target gas via specially designed bulk-optics-based cells placed at the fiber’s ends. This solution provides relatively fast fiber core filling time, however being only efficient while an overpressure is used to force the gas flow through the core, not the diffusion. Therefore, searching for alternative ways of fiber filling with the target gas is necessary. We propose a method of processing the fiber structure using a femtosecond laser allowing for non-invasive accessing the fiber core for more efficient and faster gas diffusion into it through the fabricated microchannels. The fiber structure modification was optimized in a way that does not introduce any unwanted damage of the fiber e.g. cracks on the glass parts or cladding capillaries. The performed experiments have indicated that the laser-processing of the ARHCF structure introduces negligible transmission loss regardless of the number of fabricated microchannels and their length (0.2dB loss for 25 microchannels), confirming the proposed method suitability. |
