Fiber Optic Communication Line Code Experiment Report

A Fiber Optic Communication Line Code Experiment Report documents the design, simulation, and performance analysis of optical links using NRZ and RZ line coding schemes, including BER, Q-factor, Eye Diagram, and received power measurements.Objective

The main objectives of the experiment are to:

• Design and simulate optical fiber links using NRZ and RZ line coding schemes.
• Analyze how the choice of line coding affects Bit Error Rate (BER), Q-factor, Eye Diagram, and Received Power.
• Compare system performance across different fiber lengths (e.g., 10 km, 25 km, 75 km, 100 km) to study the impact of attenuation, dispersion, and inter-symbol interference (ISI) .

Apparatus and Software

• Optical Fiber Trainer Kit or simulation software (e.g., OptiSystem 21)
• CW Laser Source
• PRBS Generator (Pseudo-Random Bit Sequence)
• Line Encoder (NRZ or RZ)
• Mach-Zehnder Modulator (MZM)
• Optical Fiber Channel
• EDFA (Erbium-Doped Fiber Amplifier) and Optical Attenuator
• PIN Photodiode and Low-Pass Filter
• BER Analyzer, Eye Diagram Analyzer, Optical Power Meter

Experimental Procedure

1. Simulation Setup:
   • Open OptiSystem and create a new project.
   • Connect the PRBS Generator to the Line Encoder (NRZ or RZ).
   • Connect the Line Encoder output to the electrical input of the MZM.
   • Connect the CW Laser to the optical input of the MZM.
2. Channel Configuration:
   • Connect the MZM output to the optical fiber.
   • Insert EDFA and Optical Attenuator after the fiber.
   • Vary fiber lengths (10 km, 25 km, 75 km, 100 km) to study performance.
3. Receiver Setup:
   • Connect fiber output to PIN Photodiode → Low-Pass Filter.
   • Connect filter output to BER Analyzer and Eye Diagram Analyzer.
   • Connect PRBS output to BER Analyzer as reference.
   • Place Optical Power Meter before the receiver.
4. Simulation Execution:
   • Run simulations at a bit rate of 10 Gb/s with 64 samples per bit.
   • Repeat for both NRZ and RZ coding formats at each fiber length.
5. Data Recording:
   • Record Q-factor, BER, Received Power, and Eye Diagram for each configuration .

Observations and Analysis

• BER (Bit Error Rate): Lower BER indicates better system performance.
• Q-factor: Higher Q-factor corresponds to better signal separation and lower BER.
• Eye Diagram: A wide-open eye indicates low ISI and minimal distortion; a closed eye indicates signal degradation.
• Received Power: Monitors optical attenuation through the fiber; decreases with increasing fiber length.
• Comparison: NRZ coding is more bandwidth-efficient but less tolerant to noise and dispersion, while RZ coding requires more bandwidth but offers better synchronization and noise tolerance .

Report Format

A professional lab report should include:

1. Title and Objective
2. Theory: Brief explanation of NRZ and RZ coding, optical link components, and performance metrics.
3. Apparatus/Software
4. Experimental Procedure
5. Results: Tables and graphs for BER, Q-factor, Eye Diagrams, and Received Power.
6. Discussion: Analyze trends, compare NRZ vs RZ, and explain the impact of fiber length.
7. Conclusion: Summarize findings and practical implications.
8. References: Cite textbooks, lab manuals, and software documentation . This structure ensures clarity, reproducibility, and professional presentation of the fiber optic line coding experiment.