Stable Dual-Wavelength Coherent Source With Tunable Wavelength Spacing Generated By Spectral Slicing a Mode-Locked Laser Using Microring Resonator

We demonstrate a stable tunable dual-wavelength erbium-doped fiber laser generated by launching a mode-locked laser into an add-drop microring resonator. Two silicon-based high-index-contrast microring resonators with Q-factors of 1.2 × 10⁵ and 0.6 × 10 ⁵ have been used as add-drop filters independently. As a result, multiwavelength generation was achieved and demonstrated both theoretically and experimentally with free spectral range (FSR) of 0.202 and 0.404 nm corresponding to the microrings´ diameter of D=2.54 and D=1.27mm. A high-resolution tunable bandpass filter and fiber Bragg gratings (FBGs) are then used to extract a tunable and switchable dual-wavelength coherent source from the generated multiwavelength coherent source. Subsequently, the dual-wavelength coherent source with tunable FSRs from 0.404 to 3.232 nm is achieved and presented. The obtained dual-wavelength output has a side-mode suppression ratio of more than 30 dB.