Demonstration of Tunable Optical Aggregation of QPSK to 16-QAM Over Optically Generated Nyquist Pulse Trains Using Nonlinear Wave Mixing and a Kerr Frequency Comb

Abstract

A tunable and reconfigurable optical aggregation system is experimentally demonstrated. Optical Nyquist pulses are generated on multiple channels using a microresonator-based Kerr optical frequency comb and insertion of uniform lines by an intensity modulator. Data are modulated on optically generated Nyquist pulses and aggregated through nonlinear wave mixing in a periodically poled lithium niobate (PPLN) waveguide. Two quadrature-phase-shift-keying (QPSK) channels are aggregated to a single 16-quadrature amplitude modulation (16-QAM) channel of Nyquist pulses. To demonstrate the system tunability, we perform aggregation over different baud rates and different modulation formats. The reconfigurability of the system is demonstrated by aggregating two binary-phase-shift-keying (BPSK) channels into a QPSK or a 2-level amplitude-shift keying and a 2-level phase-shift keying (2-ASK/2-PSK) channel by tuning the relative phase and amplitude of the inputs. Furthermore, three BPSK channels are aggregated into one 4-ASK/2-PSK channel. The quality of the aggregated channel is investigated using two different approaches for wave mixing in the PPLN waveguide.