Laura Skladova

The paper demonstrates a spectrum slicing technique applied to PAM-4 modulated signal spectrum at 40 Gbaud baudrate for optical access networks. The spectrum slicing is shown in VPIphotonics simulation environment, where characteristics of key components are measured in the laboratory and loaded into the corresponding elements of the simulation setup. The spectrum of electrical baseband signal is sliced in four slices introducing an additional degree of freedom – higher data rate signals can be transmitted by re-using already-existing lower bandwidth transceiver components in an optical access network. This tackles the electronic bottleneck enabling the on-demand variable bandwidth allocation and extends the life span of opto-electrical components during network upgrades. Furthermore, the use of the proposed spectrum slicing technique has a positive side-effect when it comes to security concerns, as the signal spectrum is divided into slices. All slices are necessary to obtain the reconstructed signal and even if an eavesdropper gets most of the slices it is still not enough. The simulation results show that the proposed spectrum slicing and stitching approach is a viable solution to overcome the problem of limited frequency bandwidth of electrical components.

Current paper characterizes the performance of the three-radio-frequency-channels, orthogonal-frequency-division-multiplexed (OFDM) radio-over-fiber (RoF) transmission system in terms of error-vector-magnitude and received optical signal power for a typical 10 GHz receiver obtained by the comprehensive simulations. The impact of the transmitted OFDM channels' signal-to-noise ratio (SNR) is also considered. We demonstrate that the SNR decrease from 40 dB to 25 dB results in an error vector magnitude (EVM) increase of up to 4 %. Furthermore, we propose the approach for allowing adjusting these results to other receiver sensitivity and responsivity values by introducing a delta in received optical signal power eliminating additional simulation or complicated calculations. The feasibility of the adjustments with a precision of up to 0.001% of the EVM is proved.

Optical frequency comb (OFC) generators based on whispering gallery mode (WGM) microresonators have a massive potential to ensure spectral and energy efficiency in wavelength-division multiplexing (WDM) telecommunication systems. The use of silica microspheres for telecommunication applications has hardly been studied but could be promising. We propose, investigate, and optimize numerically a simple design of a silica microsphere-based OFC generator in the C-band with a free spectral range of 200 GHz and simulate its implementation to provide 4-channel 200 GHz spaced WDM data transmission system. We calculate microsphere characteristics such as WGM eigenfrequencies, dispersion, nonlinear Kerr coefficient with allowance for thermo-optical effects, and simulate OFC generation in the regime of a stable dissipative Kerr soliton. We show that by employing generated OFC lines as optical carriers for WDM data transmission, it is possible to ensure error-free data transmission with a bit error rate (BER) of 4.5 × 10⁻³⁰, providing a total of 40 Gbit/s of transmission speed on four channels.