Extremely short distributed Bragg reflector fibre lasers with sub-kilohertz linewidth and ultra-low polarization beat frequency for sensing applications

摘要: We report the fabrication, characterization and application of extremely short linear-cavity distributed Bragg reflector fibre lasers (DBR-FLs) written in commercial erbium-doped fibres. The DBR-FL has a total length 7 mm, which nominal cavity is 0.4 mm length, making it shortest being reported. Two distinct spectral properties are observed: ultra-narrow linewidth ultra-low polarization beat frequency, measured to be 0.22 kHz 18.9 MHz, respectively. For former, FLs find applications high sensitivity interferometric sensing, optical frequency metrology coherent communications, whereas for latter, such low beneficial construction low-cost simple demodulator electronics sensor signal demodulation. relative intensity noise measurement showed that relaxation oscillation peak 120 −75 dB Hz−1, FL exhibited low-noise characteristics, with an −107 Hz−1 at 1 MHz. demonstrate use these efficiently pumped serially multiplexed array suitable practical sensing applications. configurations were tested, namely individual fabricated sections EDF connected via passive fibres all along single EDF.