兆赫兹重复频率的锁模激光系统在透明电介质内写波导具有独特的优势，该重复频率被证明能够在玻璃内有效制备高质量低损耗的波导。目前满足此应用要求的几种锁模激光系统中，光纤啁啾放大系统和基于腔倒空的固体激光系统只能输出百飞秒的激光脉冲，限制了此类系统的应用范围。基于多通单元的钛宝石锁模激光系统的成本又比较高，限制了飞秒激光的普及。本项目旨在基于将线性色散器件和多通单元技术相结合的方案，研究并构建兆赫兹重复频率的低成本高质量飞秒光纤激光振荡系统。设计并制备本身不具有非线性而仅提供正色散的介质薄膜器件，将其用于全正色散的锁模光纤激光振荡系统内，进一步展宽腔内脉冲的时域脉宽进而降低峰值功率，克服脉冲积累过多的非线性相移对输出脉冲能量的限制，输出高能量的飞秒激光脉冲。

Waveguide writing in transparent dielectrics can benefit a lot from the unique properties of ultrashort pulses delivered from mode-locked lasers working at megahertz repetition rate, and this repetition rate was found to be favorable to fabrication of high-quality and low-loss waveguide in glass samples. Several mode-locked lasers for such applications, such as the fiber chirped pulse amplifier lasers and cavity dumping based solid state lasers, can only deliver ultrashort pulses with pulse duration of hundreds of femtosecond. This relatively long duration limits the application fields of these systems. The high cost of the multipass-cell (MPC) based Ti Sapphire mode-locked lasers still limit the popularization of fs-laser-based applications. This project proposes a solution to building a low-cost and high quality mode-locked fiber oscillator system working at megahertz repetition rate, which is based on the combination of the MPC and the linear dispersion devices. In this project, we plan to design and fabricate dielectric thin-film based devices providing normal dispersion without nonlinearity. Application of this device into the development of mode-locked fiber lasers in all normal-dispersion regime may further broaden the intracavity pulse durations. Thus, the reduced peak power may result in lowered nonlinear phase-shift, allowing a mode-locked fiber laser to deliver fs pulses with enhanced pulse energies.