Spectral splicing for an OFDR sensing system using a DBR laser

A spectral splicing method is proposed for an optical frequency domain reflectometry (OFDR) sensing system using a distributed Bragg reflector (DBR) laser. An external cavity tunable laser (ECTL) is used in a conventional OFDR sensing system. There are no reports to our knowledge about using a DBR laser as the light source for an OFDR sensing system. A DBR laser has the advantages of small size, no mechanical scanning, easy integration, and low cost. However, due to the mode hopping, the wavelength can only be continuously tuned in the range of about 1 nm. The spectral splicing method was used to splice 39 partially overlapping Rayleigh scattering signals into a continuous signal with wavelength of 35.174 nm. Distributed optical fiber strain sensing with 5 mm spatial resolution is realized. The strain range is ±2500µε, and the maximum error of the measured strain is 9.91 µε.