Author Affiliations
Abstract
1 State Key Laboratory of Advanced Optical Communication System and Networks, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, China
2 Key Laboratory of Precision Opto-Mechatronics Technology, Ministry of Education, School of Instrumentation Science & Optoelectronics Engineering, Beihang University, Beijing 100191, China
We present an Er-doped fiber (Er:fiber)-based femtosecond laser at 780 nm with 256 MHz repetition rate, 191 fs pulse duration, and over 1 W average power. Apart from the careful third-order dispersion management, we introduce moderate self-phase modulation to broaden the output spectrum of the Er:fiber amplifier and achieve 193 fs pulse duration and 2.43 W average power. Over 40% frequency doubling efficiency is obtained by a periodically poled lithium niobate crystal. Delivering through a hollow-core photonic bandgap fiber, this robust laser becomes an ideal and convenient light source for two-photon autofluorescence imaging.
140.7090 Ultrafast lasers 140.3500 Lasers, erbium 140.3515 Lasers, frequency doubled Chinese Optics Letters
2019, 17(7): 071405
1 北京航空航天大学仪器科学与光电工程学院, 北京 100191
2 北京大学信息科学技术学院, 北京 100871
内窥镜物镜是双光子成像应用于医疗内窥成像的关键部件，物镜的成像质量和信号光收集效率对最终图像的质量至关重要。为光纤扫描式双光子成像系统设计了一款高收集效率、大视场、结构紧凑的物镜。在该系统中，920 nm飞秒激光从双包层光纤纤芯部分出射，经过物镜后激发样本，激发出的460 nm二次谐波和510 nm荧光再次经过物镜后被收集到光纤包层中。在此过程中，为了提高荧光的收集效率，对物镜组进行轴向色差设计，以使更多的荧光进入光纤包层部分。利用Zemax光学设计软件进行系统优化设计，设计结果表明：物镜组在920 nm波长下全视场范围内的调制传递函数在700 lp/mm处大于0.25，满足激发光的使用要求；在Zemax软件非序列模式下,将设计的物镜和传统梯度折射率物镜的信号光收集效率进行比较，仿真结果显示，所设计的物镜的信号光收集效率高达54%，比传统梯度折射率物镜提高了2倍以上。
光学设计 双光子荧光成像 内窥镜 收集效率 激光与光电子学进展
2018, 55(7): 071801
