Linewidth Tolerance for THz Communication Systems Using Phase Estimation Algorithm

This paper presents the impact of signal linewidth on photonic THz wireless systems using phase estimation (PE) algorithms at the receiver. The penalty associated with signal linewidth, as well as the optical linewidth requirements for systems using free-running lasers are evaluated using extensive Monte Carlo simulations for different modulation formats. The BER performance and power penalty induced by signal linewidth are also measured experimentally by varying the linewidth of the local oscillator laser. Simulation and experimental results show similar penalty trends. Differences between them are likely to be due to impairments not considered in the simulations and the THz signal linewidth being bigger than the sum of the optical linewidths of the two free-running lasers used in the experiment

Coherent Frequency Tuneable THz Wireless Signal Generation Using an Optical Phase Lock Loop System

We demonstrate experimentally, for the first time, the photonic generation of a continuous tunable THz wireless signal based on using an optical phase lock loop (OPLL) subsystem and optical frequency comb generator (OFCG). The OPLL is employed to select one line from the optical comb and shift it by the desired frequency offset allowing for the frequency tuneability of THz carrier signal. The selected optical tone from the OPLL is heterodyne mixed with another selected optical line of the optical comb to generate a stabilized THz frequency carrier with a low phase noise. Full system operation is demonstrated by transmitting wirelessly a THz signal modulated with 10 Gbaud QPSK data. The system evaluation is carried out for four selected THz carrier frequencies obtained by tuning the laser included in the OPLL. This configuration is a promising architecture that would allow a THz carrier to be flexibly generated at the central office with high frequency stability and low phase noise