Mode-locked performance of hybrid soliton pulse source utilizing fiber grating external cavity lasers

Mode-locking characteristic of hybrid soliton pulse source (HSPS) utilizing linearly chirped raised-cosine flat top apodized fiber Bragg grating (FBG) is investigated by using coupled-mode equations. It is found that the fundamental repetition frequency range of HSPS is significantly extended by using linearly chirped raised-cosine flat top apodized FBG instead of linearly chirped Gaussian apodized FBG. The range of repetition frequencies over which proper mode-locking is obtained is 2–3.3 GHz with linearly chirped raised-cosine flat top apodized grating whereas this range is 2.1–2.95 GHz with linearly chirped Gaussian apodized grating.