Heterodyne detection technique using stimulated Brillouin scattering and a multimode laser

Area of Science:

• Optics and Photonics
• Sensing Technologies
• Materials Science

Background:

• Distributed temperature sensing (DTS) is crucial for monitoring environments.
• Stimulated Brillouin scattering (SBS) is a key technique in DTS.
• Existing SBS methods face limitations in signal processing and cost.

Purpose of the Study:

• To present a novel method for distributed temperature sensing using multiple axial laser modes.
• To reduce the Brillouin beat frequency for simpler signal processing.
• To enable the use of low-cost detectors and conventional signal processing techniques.

Main Methods:

• Utilizing multiple axial laser modes in a stimulated Brillouin scattering setup.
• Stimulating a Stokes wave with a temperature-dependent Brillouin frequency shift.
• Employing optical heterodyning to mix the Stokes wave with a second axial laser mode.
• Using diode-pumped solid-state lasers to achieve frequency reduction.

Main Results:

• Demonstrated the first use of multiple axial laser modes for SBS-based DTS.
• Achieved a temperature-dependent Brillouin frequency shift in the 13-GHz range.
• Reduced the Brillouin beat frequency to the 500-MHz range via optical heterodyning.
• Successfully generated and evaluated a beat signal in a lower frequency range.

Conclusions:

• The proposed method simplifies signal processing for SBS-based DTS.
• The use of multiple axial laser modes and optical heterodyning allows for cost-effective temperature sensing solutions.
• This technique opens possibilities for wider adoption of advanced distributed temperature sensing.