Patent ID: 11899333
Assignee: NOKIA SOLUTIONS AND NETWORKS OY
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 14:
15. An apparatus, comprising:
an optical modulator including a parallel-nested pair of Mach-Zehnder Interferometers, each arm of the Mach-Zehnder Interferometers including one or more Electro-Absorption Modulators therein; and
an electronic controller electrically connected to drive the Mach-Zehnder Interferometers such that the optical modulator outputs an optical carrier modulated according to a quadrature amplitude modulation constellation with at least five different symbols; and
wherein the electronic controller is connected to apply intermediate voltages to drive a first of the Mach-Zehnder Interferometers to modulate the optical carrier to have at least three different modulation phases.