Laser Dynamics of High Repetition Rate Hybrid Mode-locked Er-doped Fiber Lasers

• Main Authors: Luo, Cheng-Jhih, 羅丞志
• Other Authors: Lai, Yinchieh
• Format: Others
• Language: en_US
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/98nq5u

博士 === 國立交通大學 === 光電工程研究所 === 107 === In this thesis work we investigate experimentally and theoretically the laser dynamics of an environmentally stable hybrid mode-locked Er-doped fiber laser with a sigma-type laser cavity. We develop a new laser noise calculation model based on the linearized back-propagation approach for the master equation. Due to the deterministic computation nature, the developed model can calculate complicate noise problems with less computation. The reliability and accuracy of the model are verified through working out some examples for determining different kinds of noises. We find a novel timing jitter cancellation effect based on active amplitude modulation mode-locked lasers. It is observed that the timing jitter can be slightly reduced through propagating the pulses in a piece of extra-cavity opposite-sign dispersive medium. We then apply the noise calculation model to study the relative intensity noises (RIN) of the bound soliton mode-locking state. We have experimentally investigated the laser characteristics of single and bound soliton mode-locking states including the state transition behavior and the RINs. We find an interesting bound soliton formation process and also find that the bound soliton state can have a smaller RIN compare to the single soliton state. Finally we achieve 100 GHz mode-locking by incorporating an intra-cavity Fabry-Pérot etalon and a section of high nonlinearity fiber. A power control loop is employed to stabilize the laser power variation to only near 0.1%. We observe different mode-locking results by replacing different finesse etalons (finesse = 6 and 100) with the turning on/off of an intra-cavity active amplitude modulator. The laser can be operated under the 100 GHz continuous passive mode-locking state and the 100 GHz burst-mode hybrid mode-locking state with very good stability. Under the burst-mode hybrid mode-locking state, the pulse quality enhancement effect is observed with the use of an active amplitude modulator. Numerical simulation based on the discrete/lumped laser cavity model is carried out to verify the experimental results. Nice agreement has been achieved to support our understanding about the observed laser dynamics.