Abstract
Brillouin optical correlation domain analysis (BOCDA) is an established method for the measurement of Brillouin frequency distribution, where direct modulation of a distributed feedback laser diode (DFB-LD) is usually adopted to implement a frequency-modulated light source. Recently, we reported that a phase delay occurring between the amplitude and frequency variations, called AM-FM phase delay, in the output of the modulated DFB-LD can cause considerable errors in the Brillouin frequency measured by a BOCDA system. The error induced by the AM-FM phase delay is systematic since it cannot be suppressed by averaging process while constantly distorts the distribution map of Brillouin frequency. In this paper, we demonstrate the suppression of the adverse effects of the AM-FM phase delay using an injection-locked DFB-LD as a light source of BOCDA system. Theoretical explanation on the origin of the systematic error in the BOCDA measurement is provided by simulations. The investigation on the modulation characteristics of the master and slave LD's in the injection-locking is performed, the result of which shows that the injection locking not only reduces the depth of amplitude modulation, but also keeps the phase delay of near 180° in a wide range of modulation frequency. In test measurements, the systematic errors are reduced by more than 70% on average using the slave LD as a common light source of the BOCDA system.
© 2019 IEEE
PDF Article
More Like This
Cited By
You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.
Contact your librarian or system administrator
or
Login to access Optica Member Subscription