Experimental OFDM transmission performance analysis in a SOA - fiber cavity laser

Area of Science:

• Optical Communications
• Semiconductor Lasers

Background:

• Fiber cavity lasers with semiconductor optical amplifiers are key for high-speed optical transmission.
• Orthogonal Frequency-Division Multiplexing (OFDM) is a crucial modulation technique in modern communication systems.

Purpose of the Study:

• To experimentally investigate OFDM transmission performance using a bi-directional fiber cavity laser.
• To analyze the impact of optical cavity modes and interference on OFDM signal quality.

Main Methods:

• Experimental setup utilizing a semiconductor optical amplifier-based bi-directional fiber cavity laser.
• OFDM transmission with varying subcarrier configurations and sinusoidal modulation.
• Error Vector Magnitude (EVM) measurements to quantify system performance.
• Analysis of inter-symbol and inter-frame interference, including a proposed pre-compensation method.

Main Results:

• OFDM transmission EVM improved significantly with increased subcarriers per frequency interval.
• Resonances in the laser's frequency response were observed relative to optical cavity modes.
• A pre-compensation technique reduced EVM from 21.4% to 9.6% (4-QAM) and 26.8% to 13.2% (16-QAM), mitigating round-trip echo effects.

Conclusions:

• The fiber cavity laser system shows promise for enhanced OFDM transmission.
• Optimizing subcarrier density and employing pre-compensation are effective strategies for improving signal integrity and reducing interference.