Development of a Long Period Fiber Grating Interrogation System Using A Multimode Laser Diode.

Area of Science:

• Photonics and Sensing Technology
• Optical Fiber Sensors
• Instrumentation and Measurement

Background:

• Traditional interrogation systems for optical fiber gratings often rely on expensive and bulky equipment like optical spectrum analyzers or CCD spectrometers.
• A key challenge in fiber grating sensing is the development of cost-effective and compact interrogation methods.
• Long Period Fiber Gratings (LPFGs) offer sensing capabilities but require efficient interrogation techniques.

Discussion:

• This paper details a novel interrogation system for LPFGs that utilizes the temperature response of a multimode laser diode.
• The system creates a discrete attenuation spectrum by performing a spectral sweep across a rejection band, which is then reconstructed using curve fitting.
• This approach significantly reduces system cost and dimensions compared to conventional methods.

Key Insights:

• The developed system achieves accurate interrogation of LPFGs with measurement errors as low as 0.4 nm for central wavelength and 0.4 dB for attenuation over a 10 nm window.
• The use of a multimode laser diode as the interrogation source provides a cost-effective alternative to broadband sources and complex spectrometers.
• The system's ability to restore the original spectrum through curve fitting ensures reliable data acquisition.

Outlook:

• The low cost and compact nature of this interrogation system make it highly suitable for field applications, particularly those involving slow-changing measurands.
• Further research could explore expanding the operational window or enhancing the measurement speed for dynamic sensing applications.
• This technology has the potential to democratize the use of fiber grating sensors in various industrial and environmental monitoring scenarios.