Grating-free and highly wavelength-stabilized coupled-cavity semiconductor lasers with monolith integration of an active ring resonator

A grating-free coupled-cavity laser (CCL) consisting of an FP semiconductor laser parallelly coupled with an active ring resonator is demonstrated. The device exhibits a stable and accurate single-mode output (<1 GHz/mA), featuring four wavelength switchable channels spaced approximately 4 nm apart and achieving a side-mode suppression ratio (SMSR) of up to 43.7 dB. The superiority of simple structure, stable single-mode performance, wavelength tunability, and monolithic integration with other optical components make this CCL a promising alternative to grating-based devices.