Return-to-zero modulation with electrically continuously tunable duty cycle using single NRZ modulator

Two optical return-to-zero (RZ) modulation techniques are discussed, both based on a single Mach-Zehnder modulator driven by non-return-to-zero (NRZ) electrical signals. Both methods allow for continuously electrically tunable duty cycles and lead to chirped RZ formats. We demonstrate and discuss two RZ transmitter setups that generate optical RZ signals with electrically continuously tunable duty cycle using a single, NRZ-driven Mach-Zehnder modulator.