A scheme of fiber Bragg grating(FBG) wavelength demodulation based on reflective semiconductor optical amplifier(R-SOA) is proposed and demonstrated.The tunable narrowband laser consists of a R-SOA and a tunable FBG,of which the Bragg period is tunable through a one-dimensional adjustor.The one-dimensional adjustor,which is connected with a step motor controlled by a Programmable logic controller(PLC),can control the wavelength of the laser output.The tunable narrowband laser,the FBG sensor,the ...