Performance analysis of PLC-based 32-channel arrayed waveguide grating used for FBG interrogator

The Fiber Bragg grating (FBG) is an optical fiber component that reflects or diffracts optical signals of specific wavelengths through periodic refractive index changes inside it. Currently, the use of arrayed waveguide grating (AWG) to interrogate such optical signals is a popular research topic at present. Using the planar lightwave circuit, we designed and fabricated a 32-channel AWG. The AWG has an insertion loss of less than 4 dB, a 3 dB bandwidth of about 1.76 nm, and a crosstalk of non-adjacent channels of less than -28 dB. Additionally, we integrated the AWG with a photodetector (PD) array and built a corresponding wavelength interrogation system, which was tested using three different interrogation methods. The test results indicate that when using the linear fitting, this AWG provides the best results using the dual-channel edge filtering method with an interrogation range of 1.6 nm and an interrogation accuracy of 18.9-20.1 pm. The interrogation accuracies of the relative intensity method are 9.4 pm and 3.7 pm when Gaussian and Lorentzian fittings are used.