FBG-referenced interrogating system using a double-ring erbium-doped fiber laser for high power and broadband

In this study, a double-ring erbium-doped fiber (EDF) laser with an optical switch and a fiber Bragg grating (FBG)-referenced interrogating system was developed and demonstrated. This double-ring configuration can achieve high power amplified spontaneous emission, enabling laser oscillation even within the L-band. The output range and signal-to-noise ratio (SNR) of the double-ring EDF laser were measured to be 1512-1610 nm and 55 dB. In addition, the interrogating system using FBGs for reference resulted in precision improvement of ∼25 pm over those achieved in previous studies, reaching a precision of about 7 pm. The high power, broad tuning range, and sufficiently high precision of the proposed interrogating system make it promising for use in FBG-based sensing applications.