Compensation of noise floor distortion in long-range simplified optical correlation-domain reflectometry without the use of electrical spectrum analyzer

Abstract

In simplified optical correlation-domain reflectometry (OCDR) without the use of an electrical spectrum analyzer (ESA), the noise floor of the reflectivity distribution is distorted in long-range measurement, which sometimes causes significant errors in the distributed reflectivity measurement. Herein, we experimentally analyze the distorted noise floor by high-speed ESA-free OCDR and clarify the origin of the noise floor. Then we show that this noise floor can be compensated by appropriate filtering. Consequently, distributed reflectivity measurement over a 1.1 km long sensing fiber is properly performed at a repetition rate of 100 Hz.

Observation of Rayleigh scattering by simplified optical correlation-domain reflectometry without frequency shifter

“…As an alternative to OTDR and OFDR, optical correlationdomain reflectometry (OCDR) [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] has been developed on the basis of the synthesis of optical coherence functions. 15) OCDR can be implemented at a relatively low cost and has a unique advantage called random accessibility, i.e.…”

“…30) However, these improvements come at a cost of significant noise for long-range measurements, as has been reported previously. 31) Note that the key difference between ESA-free OCDR and AOM-free OCDR is in their electrical signal processing, while their spatially resolving techniques are identical, resulting in the same measurement range in principle. Here, we focus on the AOM-free OCDR system with the use of an ESA.…”