Optical Frequency Combs Generated in Silica Microspheres in the Telecommunication C-, U-, and E-Bands

Photonics 2021
Elena A.Anashkina, Maria P.Marisova, Toms Salgals, Jānis Alnis, Ilya Lyashuk, Gerd Leuchs, Sandis Spolītis, Vjačeslavs Bobrovs, Alexey V.Andrianov

Optical frequency combs (OFCs) generated in microresonators with whispering gallery modes are demanded for different applications including telecommunications. Extending operating spectral ranges is an important problem for wavelength-division multiplexing systems based on microresonators. We demonstrate experimentally three spectrally separated OFCs in the C-, U-, and E-bands in silica microspheres which, in principle, can be used for telecommunication ap-plications. For qualitative explanation of the OFC generation in the sidebands, we calculated gain coefficients and gain bandwidths for degenerate four-wave mixing (FWM) processes. We also attained a regime when the pump frequency was in the normal dispersion range and only two OFCs were generated. The first OFC was near the pump frequency and the second Ra-man-assisted OFC with a soliton-like spectrum was in the U-band. Numerical simulation based on the Lugiato–Lefever equation was performed to support this result and demonstrate that the Raman-assisted OFC may be a soliton.

Keywords
silica microsphere; optical frequency comb (OFC); Raman OFC; soliton-like spectrum; four-wave mixing
DOI
10.3390/photonics8090345
Hyperlink
https://www.mdpi.com/2304-6732/8/9/345

A.Anashkina, E., P.Marisova, M., Salgals, T., Alnis, J., Lyashuk, I., Leuchs, G., Spolītis, S., Bobrovs, V., V.Andrianov, A. Optical Frequency Combs Generated in Silica Microspheres in the Telecommunication C-, U-, and E-Bands. Photonics, 2021, Vol. 8, No. 9, Article number 345. ISSN 2304-6732. Available from: doi:10.3390/photonics8090345

Publication language
English (en)