ILYA LYASHUK
Institute of Telecommunications, Riga Technical University
FWM-based optical frequency combs for next-generation WDM fiber-optic communication system
Ilya Lyashuk*, Janis Braunfelds, Sandis Spolitis, Vjaceslavs Bobrovs
Nonlinear four-wave mixing (FWM) is one of the well-known nonlinear optical effects (NOE) and is considered to be harmful to wavelength division multiplexed passive optical networks (WDM-PON). Communication systems of this type encounter channel crosstalk and their performance degrades by the FWM effect, where non-linear interactions between channels are observed. FWM is an effect when two or more different signals with different frequencies propagate next to each other, and due to this reason, new carriers are generated. However, solutions for the useful application of the FWM effect are being studied, for instance, this NOE as a productive one can be used in fiber optical communication systems for various optical processing functions, like wavelength conversion, pulse compression, high-speed time-division multiplexing (TDM), fiber optical parametric amplifiers (FOPA), and also for the generation of optical frequency combs (OFCs) in highly nonlinear optical fiber (HNLF), where our research focuses on. To show the FWM NOE application in OFC generation, we have developed a mathematical simulation model and analyze the performance of the FWM-based OFC based 8-channel 50 GHz spaced non-return-to-zero on-off keying (NRZ-OOK) modulated dense WDM-PON transmission system with an operation range of up to 50 km over standard single-mode fiber (SMF) and bitrate of up to 10 Gbit/s per channel. The proposed FWM-based OFC generator is constructed based on two high-power continuous wave (CW) pump lasers and HNLF fiber span. We demonstrate that the generated OFC matches the ITU-T G. 694.1 frequency grid and has power fluctuations of the individual comb tones of less than 3 dB, tone to noise ratio (TNR) higher than 30 dB. The demonstrated transmission system is a promising solution for next-generation high-speed PONs.