Fig. 1. Schematic diagram of Rayleigh scattering spectrum analysis in an ODW. The inset picture represents the separation and collection of each RBS field during the continuous scattering process.

Fig. 2. Simulation of the SpE law for the kth RBS source in the continuous scattering process.(a) The frequency spectra of the kth RBS source at different filtering number of times; (b) The frequency spectra of the kth RBS source under different effective dopant degree (EDD).

Fig. 3. Theoretical prediction: the black curve with square describes the relationship between the spectral linewidth of the kth RBS source and the transmission distance L, while the blue curve with five-pointed star reveals the relationship between the spectral linewidth of the kth RBS source and the effective dopant degree (EDD).

Fig. 4. The experimental scheme for measuring the SpE of Rayleigh scattering.ISO: Optical isolator; OC: Optical circulator; C: 90:10 coupler; EDFA: Erbium doped fiber amplifier. SS: A series of sequences of the scattering system.

Fig. 5. Theoretical design of micro-cavity structure based on the SpE characteristic of Rayleigh scattering in ODW.