Long-Range, High-Spatial-Resolution Raman Distributed Optical Fiber Sensing Based on Differential Pulse Golay Coding

doi:10.16553/j.cnki.issn1000-985x.2026.0089

Abstract

Abstract: To address the trade-off between long sensing distance and high spatial resolution in conventional Raman distributed temperature sensing （RDTS）， this paper presents a sensing scheme based on differential pulse Golay codes （DPG-codes）. The approach integrates the coding gain of differential pulse Golay codes with a differential processing mechanism. By exploiting the excellent autocorrelation characteristics of Golay complementary sequences， the launched optical energy and the far-end signal-to-noise ratio are substantially increased， all while avoiding nonlinear effects within the fiber. In the proposed scheme， Golay-coded sequences independently modulated by long and short pulse widths are sequentially injected into the sensing fiber. A differential operation is then performed on the decoded backscattered Raman signals， yielding a Raman scattering response that corresponds to an equivalent pulse width of just 4 ns and thereby delivers high spatial resolution. Numerical simulation results show that， relative to conventional techniques， the DPG-codes scheme raises the signal-to-noise ratio at the fiber end by 8.89 dB and improves the temperature resolution from 33.06 ℃ to 3.54 ℃. Ultimately， a spatial resolution of 0.40 m is achieved across a sensing distance of 150.0 km.

Key words: distributed optical fiber sensing; Raman scattering; sensing distance; spatial resolution; pulse coding

CLC Number:

O436

WANG Jiale, LI Jian, ZHANG Fan, LI Lulei, WANG Rilong, ZHANG Mingjiang. Long-Range, High-Spatial-Resolution Raman Distributed Optical Fiber Sensing Based on Differential Pulse Golay Coding[J]. Journal of Synthetic Crystals, 2026, 55(8): 1213-1221.

Figures/Tables 9

Table 1 Performance comparison of representative RDTS schemes

技术方案	传感距离	空间分辨率	温度分辨率
锁模飞秒脉冲方案	3.0 m	0.01 m	—
增强型抗失真编码与波形重构方案	70.0 km	1.58 m	5.39 ℃
混沌非对称脉冲对相关增强方案	10.0 km	0.30 m	—
渐变折射率少模光纤方案	25.0 km	1.10 m	1.0 ℃
方波宽度啁啾脉冲压缩方案	45.0 km	0.50 m	—
DPG-codes方案	150.0 km	0.40 m	3.54 ℃

Fig.1 Experimental setup of the DPG-codes scheme

Fig.2 Timing diagram of the differential Golay pulse coding scheme

Table 2 Parameters related to DPG-codes numerical modeling simulation

Parameter	Physical meaning	Value
$K a s$	Raman anti-Stokes signal coefficient	3.066 41×10^-9
$n$	Refractive index of the fiber	1.5
$λ$	Raman anti-Stokes signal wavelength/nm	1 450
$Δ ν$	Raman frequency shift/THz	13.2
$l$	Length of codes/bit	128
$α 0 + α a s$	Transmission loss/（dB·km^-1）	1.18
$T 0$	Room temperature/℃	20
$T$	FUT temperature/℃	90
$τ W$	Long pulse width/ns	10
$τ N$	Short pulse width/ns	6

Table 2 Parameters related to DPG-codes numerical modeling simulation

Parameter	Physical meaning	Value
$K a s$	Raman anti-Stokes signal coefficient	3.066 41×10^-9
$n$	Refractive index of the fiber	1.5
$λ$	Raman anti-Stokes signal wavelength/nm	1 450
$Δ ν$	Raman frequency shift/THz	13.2
$l$	Length of codes/bit	128
$α 0 + α a s$	Transmission loss/（dB·km^-1）	1.18
$T 0$	Room temperature/℃	20
$T$	FUT temperature/℃	90
$τ W$	Long pulse width/ns	10
$τ N$	Short pulse width/ns	6

Fig.3 SNR based on single pulse and DPG-codes scheme

Fig.4 Temperature demodulation curve based on single pulse and DPG-codes scheme

Fig.5 Temperature resolution based on single pulse and DPG-codes scheme

Fig.6 Spatial resolution based on DPG-codes scheme

Fig.7 Spatial resolution measurement result

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