A Time-Differential BOCDA Sensor Measurement System Applied to a 1 km Long SMF Using a Semiconductor Optical...

Area of Science:

• Optical Fiber Sensing
• Photonics
• Signal Processing

Background:

• Brillouin optical correlation domain analysis (BOCDA) is a powerful technique for fiber optic sensing.
• Conventional BOCDA systems often require optical delay lines, which can limit performance and introduce complexity.
• Improving the reliability and precision of fiber optic sensing is crucial for various applications.

Purpose of the Study:

• To develop and evaluate a time-differential (TD) BOCDA sensor system.
• To eliminate the need for optical delay lines in BOCDA measurements.
• To assess the measurement stability and reliability of the TD-BOCDA system.

Main Methods:

• A 1 km sensing optical fiber was used to measure the Brillouin gain spectrum.
• A TD-BOCDA system with phase-modulated probe and pump lightwaves (2^16-1 PRBS codes at 5 Gbps) was implemented.
• The system's stability was compared using a semiconductor optical amplifier (SOA) versus an intensity modulator (MOD) for pumping.

Main Results:

• The TD-BOCDA system successfully identified a 2 cm dispersion-shifted fiber at the end of the 1 km fiber.
• The SOA pumping condition resulted in half the repeated-measurement deviation compared to the MOD condition.
• The TD-BOCDA system demonstrated measurement reliability equivalent to or better than conventional BOCDA.

Conclusions:

• The TD-BOCDA system effectively measures Brillouin gain spectra without optical delay lines.
• The system offers improved measurement stability and reliability, particularly with SOA pumping.
• TD-BOCDA presents a promising advancement in fiber optic sensing technology.