Portable Atmospheric Transfer of Microwave Signal Using Diode Laser with Timing Fluctuation Suppression

We demonstrate an atmospheric transfer of microwave signal over a 120 m outdoor free-space link using a compact diode laser with a timing fluctuation suppression technique.Timing fluctuation and Allan Deviation are both measured to characterize the instability of transferred frequency incurred during the transfer process.By transferring a 100 MHz microwave signal within 4500 s,the total root-mean-square(RMS)timing fluctuation was measured to be about 6 ps,with a fractional frequency instability on the order of 1×10-12 at 1 s,and order of 7×10-15 at 1000 s.This portable atmospheric frequency transfer scheme with timing fluctuation suppression can be used to distribute an atomic clock-based frequency over a free-space link.

307 W high-power 1018 nm monolithic tandem pump fiber source with effective thermal management

We report a 307 W 1018 nm Yb-doped fiber laser pumped by a single 976 nm laser diode. The cavity slope efficiency is up to 75.9% and the amplified spontaneous emission is suppressed by 54 dB. The beam quality of the output laser has an M2 factor of 1.17. Effective thermal management is considered to ensure the stable operation of our system. The power stability at the maximum output power level is measured during a period of0.5 h and the power fluctuation is less than 0.8%. This architecture can be an effective high brightness pump source of core-pumping high-power fiber amplifiers.