Frequency comb generation in WGM microsphere based generators for telecommunication applications
Jānis Braunfelds, Rihards Mūrnieks, Toms Salgals, Inga Brice, T. Sharashidze, Ilya Lyashuk, Armands Ostrovskis, Sandis Spolītis, Jānis Alnis, Jurģis Poriņš, Vjačeslavs Bobrovs
Abstract
Abstract We review the frequency comb generation process, main microresonator parameters such as free spectral range (FSR) and Q -factor, previously used optical frequency comb (OFC) generator parameters and resulting frequency combs, as well as the implementation of OFC for optical data transmission. An optical frequency comb is produced in a setup based on a tapered fibre and a SiO 2 microsphere. The generated frequency comb has a frequency spacing of 2 nm or 257 GHz. During the fabrication of a tapered fibre from SMF28, use is made of the transmission signal to control the taper pulling process. The final measured tapered fibre transmission is ∼96%. A microsphere whispering gallery-mode resonator (WGMR), exhibiting a Q -factor of at least 2 × 10 7 , is fabricated from an optical fibre with a thicker core than SSMF. Moreover, for future experiments, a frequency comb generator based on a free-space setup consisting of lenses, a prism, and a microsphere is developed, and the Q -factor dependence on different distances between the prism and the microsphere is investigated.