2 results
Search Results
Now showing 1 - 2 of 2
- ItemBunimovich Stadium-like Microsphere for Randomized Fiber Laser Operation(Basel : MDPI, 2018) Silveira, Beatriz; Gomes, André D.; Becker, Martin; Schneidewind, Henrik; Frazão, OrlandoA silica resonator was demonstrated for random laser generation. The resonator consisted of a conventional microsphere fabricated in an optical fiber tip through electric arc discharge, and modifications to its geometry were carried out to create asymmetry inside the silica structure. The resulting Bunimovich stadium-like microsphere promotes multiple reflections with the boundaries, following the stochastic properties of dynamic billiards. The interference of the multiple scattered beams generates a random signal whose intensity was increased by sputter-coating the microstadium with a gold thin film. The random signal is amplified using an erbium-doped fiber amplifier (EDFA) in a ring cavity configuration with feedback, and lasing is identified as temporal and spectral random variations of the signal between consecutive measurements.
- ItemA Brief Review of New Fiber Microsphere Geometries(Basel : MDPI, 2018-7-11) Delgado Gomes, André; Silva Monteiro, Catarina; Silveira, Beatriz; Frazão, OrlandoA brief review of new fiber microsphere geometries is presented. Simple microspheres working as Fabry–Perot cavities are interrogated in reflection and in transmission. Two microspheres were also spliced together, and subjected to different physical parameters. These structures are an alternative solution for load measurement and, when read in transmission, it is also possible to apply strain. Moreover, the structure is capable of being used under extreme ambient temperatures up to 900 °C. Random signal in cleaved microspheres was demonstrated with the possibility of using it for random laser or sensing applications. All this work was developed at the Centre for Applied Photonics, INESC TEC.