Time- and wavelength-division multiplexing of FBG sensors using a semiconductor optical amplifier in ring cavity configuration

An interrogation system based on two semiconductor optical amplifiers for weak fiber Bragg gratings

“…3. Given that the sensor array includes 125 FBGs with the reflectivity of 0.2% (-27 dB), the reflected power from the 125-th FBG will decline 2.17 dB as (4). agrees with our theoretical calculation.…”

“…Therefore, this method has the considerable potential for increasing the number of the multiplexing sensor. Several types of TDM schemes with a resonant cavity based on a semiconductor optical amplifier (SOA) were proposed [3][4][5]. Notably, these methods improve the signal power with a single SOA, and the interrogated FBGs with a reflectivity of more than 1% are required.…”

Polarization multiplexed interrogation technique for FBG sensor array

“…The motivation behind this concept to be used in FBG sensor interrogation lies in polarization division multiplexing (PDM) implementation in the high speed optical network [19,20]. Here, each FBG sensor needs to have a polarizer with the known predetermined angle of polarization.…”

“…The general requirement of an ideal interrogation method is to have high resolution, ability to support multiplexing, be robust and cost effective. Various interrogating techniques are being used for FBG sensors but the commercial interrogators for FBG sensors can be broadly classified as TDM, WDM, SDM, and their various combinations for the improved performance [15,[17][18][19][20][21][22]. TDM systems uses a pulse from a broadband light source, and all sensors are nominally written at the same wavelength with low reflectivity, thus allowing some light to pass down the fiber to illuminate the sensors downstream.…”

“…The WDM sensor technology is well-developed but sensors come with large size and relatively high cost. The TDM/WDM topology is able to address the large number of FBG sensors and is one of the most promising techniques for quasi-distributed measurement [20][21][22][23][24]. The drawback of this type of implementation is the limited scanning frequency, which would limit the response of the system to dynamic signals and transients, and limited spatial resolution.…”