The photocathode drive laser system in the Institute of High Energy Physics (IHEP) has been upgraded. An all-fiber drive laser system has been developed using photonic crystal fibers and photonic crystal rods as the main gain medium. This system has been operated stably. The output infrared (IR) power reaches 116.2 W. The pulse width and maximum output power of the green laser generated by the second harmonic generation (SHG) are less than 2 ps and about 39.4 W, respectively. The SHG efficiency exceeds 60%. This paper introduces the development of the drive laser system and reports the measurement results of the performance test.

In theory, a 180 $^{\circ}$ hybrid bridge can be used as a variable power divider and combiner. This study focuses on applying the variable power divider and combiner to a high-vacuum and high-power environment, aiming at realizing future applications in particle accelerators. Beginning from theoretical derivation, this article reports the design of an $S$ -band variable waveguide power divider and combiner based on a Magic Tee. The simulation results are consistent with those predicted by theory. A prototype of the variable power divider was fabricated for the microwave cold test, and the measurement results verify the variable power division. The power division ratio curve is consistent with the theoretical and simulated curves. The variable power combiner was experimentally verified by combining the Magic Tee and coaxial components. The measurement results are consistent with those of numerical analysis. Simulations evaluating the high-power performance reveal that the matching probe of the Magic Tee and the phase shifting plate tip of the straight waveguide phase shifter could not satisfy the high-power requirement. Thus, the structure of the Magic Tee is improved in the proposed design, and a 3-dB bridge waveguide phase shifter was adopted. The simulation results show qualified performance for high-power applications, and other microwave performance characteristics also show great improvement. The study lays a good foundation for application in future high-vacuum and high-power environments.