1：Experimental Design and Method Selection:

The study uses numerical simulations via the OptSim commercial tool to model UWB signal generation. Two techniques are compared: nonlinear medium-based (using HNLF or SOA) and optical delay line-based. The nonlinear technique involves cross-phase modulation (XPM) in the medium, followed by PM-to-IM conversion using an optical band-pass filter (OBPF). The delay line technique uses optical splitting, delaying, and subtraction to generate pulses.

2：Sample Selection and Data Sources:

Simulated optical signals are generated with specific parameters, including a pulsed laser source at 1549 nm modulated with 5 Gbps baseband data, a CW laser at 1548 nm, and a white light source to introduce ASE noise. No real-world samples are used; it is entirely simulation-based.

3：List of Experimental Equipment and Materials:

Key components include pulsed laser source, CW laser, optical couplers, Mach-Zehnder modulator, erbium-doped fiber amplifier (EDFA), highly nonlinear fiber (HNLF), semiconductor optical amplifier (SOA), optical band-pass filter (OBPF), single-mode fiber (SMF), photodetector, electrical amplifier, electrical splitter, low-pass filter, optical delay line, variable optical attenuator, and subtractor. Parameters for HNLF (length 0.4 km, dispersion -1.7 ps/nm/km, dispersion slope 0.023 ps/nm2/km, nonlinear coefficient 18/W·km) and SOA (cavity length 5e-4 m, injection current 0.3 A, differential gain 2.78e-20 m2, initial carrier density 3e24 m?3) are specified.

4：4 km, dispersion -7 ps/nm/km, dispersion slope 023 ps/nm2/km, nonlinear coefficient 18/W·km) and SOA (cavity length 5e-4 m, injection current 3 A, differential gain 78e-20 m2, initial carrier density 3e24 m?3) are specified. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: For the nonlinear technique, the pulsed signal is coupled with CW probe and noise source, amplified by EDFA, passed through the nonlinear medium (HNLF or SOA) to induce chirp via XPM, filtered by OBPF for PM-to-IM conversion, transmitted over 20 km SMF, photodetected, and processed for BER analysis. For the delay line technique, the signal is split, delayed, attenuated, photodetected, subtracted, and similarly processed. BER is measured at different OSNR values.

5：Data Analysis Methods:

BER is calculated using the BER estimator in the simulation tool. Results are plotted against received optical power for various OSNRs to compare performance and noise resilience.