Flexible high-order quadrature amplitude modulation transmitter for elastic optical networks

To adapt to the network dynamics and support elastic network resource allocation in the future elastic optical networks, optical transmitter with flexibility and re-configurability in modulation formats becomes indispensable, offering network providers flexibility in transport bandwidth. In this paper, we discuss our proposed two flexible high-order quadrature amplitude modulation (QAM) transmitter schemes, including (i) a flexible transmitter based on tandem in-phase/quadrature (IQ) modulators for generating 16QAM, 32QAM, 64QAM signals; and (ii) a scheme based on monolithically-integrated quad-Mach-Zehnder IQ modulator (QMZ-IQ) with binary driving electronics for synthesizing minimum phase-shift keying (MSK), quadrature phase-shift-keying (QPSK), 8-ary phase-shift keying (8PSK), and 16QAM signals. These schemes provide different approaches to configure a flexible high-order QAM transmitter, either using cascaded off-the-shelf modulators, or via highly-integrated monolithic modulator. These flexible and reconfigurable transmitter schemes provide the network providers different flexible transmitter solutions suitable for different application scenarios in elastic optical networks.