Table 2.
State-of-the-art of multiplexed optical fiber sensor networks for water level monitoring.
| Year/Reference | Interrogation | Multiplexing | No. of Channel | Type of SU | Modulation Mechanism |
|---|---|---|---|---|---|
| 2001/[31] | OTDR | TDM | 2 | Right angle prism probe (R 5) | Intensity |
| 2004/[32] | LD array + OPM | SDM (+FDM) | 8 | POF sensor head (T 6) | Intensity |
| 2005/[33] | BLS + OSA 1 | CWDM | 4 | FBG array (R) | Wavelength |
| 2010/[34] | TLS 2 + OSA | CWDM | 2 | 105/125 MMF 7 (R) | Intensity |
| 2011/[35] | OTDR | TDM | 6 | Bending loss sensor (R) | Intensity |
| 2014/[36] | OTDR | TDM | 3 | Special probe with NaCl solution (R) | Intensity |
| 2015/[37] | BLS + OSA | CWDM | 5 | FBG array (R) | Wavelength |
| 2015/[38] | OFDR 3 | TDM | 2 | Thin core fiber (R) | Intensity |
| 2017/[39] | OCDR 4 | TDM | 10 | FC 8-type Fiber Connector (R) | Intensity |
| 2018/[40] | TLS + OSA | CWDM | 2 | FBG-embedded diaphragm sensor (R) | Wavelength |
| 2019/[41] | BLS + OPM | SDM | 4 | Cleaved end facet SMF (R) | Intensity |
| 2019/[42] | BLS + OSA | DWDM | 11 | Optical patch cord (R) | Intensity |
| 2020/[43] | BLS + OPM | DWDM | 11 | Optical patch cord (R) | Intensity |
1 OSA: optical spectrum analyzer, 2 TLS: tunable light source, 3 OFDR: optical frequency domain reflectometry, 4 OCDR: optical coherence domain reflectometry, 5 R: reflective sensing type, 6 T: transmissive sensing type, 7 MMF: multimode fiber, 8 FC: Ferrule Connector, OTDR: optical time-domain reflectometer, LD: laser diode, BLS: broadband light source, TDM: time division multiplexing, SDM: space division multiplexing, FDM: frequency division multiplexing, DWDM: dense wavelength division multiplexing, CWDM: coarse wavelength division multiplexing, FBG: fiber Bragg grating, and SMF: single-mode fiber.