All-optical 42.6 Gbit/s NRZ to RZ format conversion by cross-phase modulation in single SOA

Cascaded SOA configuration for NRZ-OOK to RZ-QPSK format conversion

“…The origin of the 7.8 dB power penalty can be roughly divided into three parts: 1. two OOK to BPSK format conversions; 2. original NRZ pulse shape is changed to RZ pulse shape; 3. receiver sensitivity difference between DPSK and DQPSK detections. Previous SOA based experiments show a 1.3 dB power penalty from a single NRZ-OOK to NRZ-BPSK format conversion [5] and a 0.6 dB negative penalty from NRZ pulse to RZ phase conversion [14]. Besides, DQPSK has a power penalty of around 5 dB while comparing with DPSK signal [15].…”

Advanced optical modulation and format conversion

“…This phase modulation is converted into amplitude modulation in the DI, which results in an RZ output signal with a controllable pulse-width (duty-cycle) determined mainly by the offset delay ( t) of the DI. Yang et al [66] used a piece of polarization maintaining fibre with a differential delay ( t), along with two polarization controllers and a polarizer to form a DI, while Zhao et al [67] used a reconfigurable Differential Group Delay (DGD) generator. Other researchers have used the same conversion scheme for multiple wavelength operations, where more than one NRZ input data sequences are converted to RZ format [68,69], as presented in Figure 2.16.…”

Simultaneous all-optical multi-channel RZ and CSRZ to NRZ format conversion

“…For years, researchers have demonstrated various conversion schemes between different OOK formats for the interface between wavelength division multiplexed (WDM) and optical time division multiplexed (OTDM) networks [1][2][3][4][5][6]. However, most of these schemes were based on a single wavelength operation and thus cannot simultaneously convert the multiple channels presented in the WDM systems, where parallel signal processing is very attractive.…”