提出了一种He气辅助熔接的全光纤型空芯光子晶体光纤(HC-PCF)低压气体腔的制备方法。通过用高压待充气体冲洗HC-PCF,确保了腔内的气体纯度;通过利用光谱监测系统监测HC-PCF降压过程及He气辅助熔接过程中CO2吸收光谱的变化,研究了HC-PCF中气体动力学运动过程;通过利用He气辅助熔接方法,制备得到压强为7 k Pa、插入损耗小于2 d B、长度为10 m的全光纤型HC-PCF低压CO2气体腔。该方法也适用于更低压强的HC-PCF气体腔的研制,且制备的气体腔具有良好的气密性和长期稳定性。
A compact and stable all-normal-dispersion mode-locked ring fiber laser with the repetition rate of 312 MHz is obtained with a wavelength-division multiplexing isolator. The compressed pulse is nearly transform-limited and the pulse width is 118 fs. It exhibits an optical efficiency of 50% and the maximum output power is about 205 mW with a 410 mW pump.
In this paper, the influences of the dispersion distribution in the cavity on the output pulse properties of the all-normaldispersion（ANDi） fiber laser are investigated. Our simulations show that, as the relative length of the dispersion fiber increases, the temporal width and the spectral bandwidth of the output pulse for an ANDi fiber laser with fixed total cavity dispersion or fiber length are decreased, while the pulse energy is enhanced and the compressed pulse width is increased.These simulation predictions have been proved by our experimental results. The reason may be that the nonlinear phase shift accumulated in the nonlinear fiber is more than that in the dispersion fiber if they have the same length.
