Transmission characteristics of a double fiber ring with a fiber Bragg grating

Abstract

The Z -domain model of a double fiber ring with a uniform fiber Bragg grating incorporated using two optical couplers and a double ring with Bragg grating configuration using three optical couplers is developed. The developed mathematical model is used to determine the transmission response. The performance of the double ring with the grating using two optical couplers is compared with previously measured results and is found to be in very close agreement. A similar double ring with a grating structure using three optical couplers is proposed. By proper optimization of grating reflectivity and power coupling ratios, a narrow full width at half-maximum with virtually zero cross talk is achieved. Compared with the double-ring configuration using two optical couplers, the proposed structure yields a higher finesse, giving much better spectral selectivity. The performance of the proposed structure as a strain sensor is investigated using the delay line signal-processing technique in the Z domain. The detection resolution in measurement of a weak strain variation is much enhanced.