[23p-P02-1~3] 3.14 Optical control devices and optical fibers

[23p-P02-2] Time-division multiplexed sensing of nearly identical fiber Bragg gratings based on a heterodyne detection technique

〇Keiji Kuroda¹, Komichi Hamada¹ (1.Kitasato Univ.)

Keywords:Fiber Bragg grating sensor, Heterodyne detection, DFB laser

We report time-division multiplexed interrogation of three nearly identical FBGs. Output from a directly modulated DFB laser is divided into two parts: a signal pulse and a reference pulse. Weak reflections of the signal pulse from the FBGs are heterodyne detected using the reference pulse and enhanced. By applying direct modulation of a DFB laser and the heterodyne detection technique, spectra of the three FBGs with a 1% reflectivity and a spatial interval of 4.5 m are clearly observed.