Direct generation of watt-level yellow Dy^(3+)-doped fiber laser

Yellow lasers(∼565–590 nm)are of tremendous interest in biomedicine,astronomy,spectroscopy,and display technology.So far,yellow lasers still have relied heavily on nonlinear frequency conversion of near-infrared lasers,precluding compact and low-cost yellow laser systems.Here,we address the challenge through demonstrating,for the first time,to the best of our knowledge,watt-level high-power yellow laser generation directly from a compact fiber laser.The yellow fiber laser simply consists of a Dy^(3+)-doped ZBLAN fiber as gain medium,a fiber end-facet mirror with high reflectivity at yellow and a 450-nm diode laser as the pump source.We comprehensively investigated the dependence of the yellow laser performance on the output coupler reflectivity and the gain fiber length and demonstrated that the yellow fiber laser with an output coupler reflectivity of 4% and a gain fiber length of∼1.8 m yields a maximum efficiency of 33.6%.A maximum output power of 1.12 W at 575 nm was achieved at a pump power of 4.20 W.This work demonstrated the power scaling of yellow Dy^(3+)-doped ZBLAN fiber lasers,showing their promise for applications in ophthalmology,astronomical exploration,and high-resolution spectroscopy.

New ultrashort pulsewidth measurement technology based on interference jitter and FPGA platform

Conventional ultrashort pulsewidth measurement technology is autocorrelation based on second-harmonic generation;however,nonlinear crystals and bulky components are required,which usually leads to the limited wavelength range and the difficult adjustment with free-space light alignment.Here,we proposed a compact all-fiber pulsewidth measurement technology based on the interference jitter(IJ)and field-programmable gate array(FPGA)platform,without requiring a nonlinear optical device(e.g.nonlinear crystal/detector).Such a technology shows a wide measurement waveband from 1 to 2.15μm at least,a pulsewidth range from femtoseconds to 100 ps,and a small relative error of 0.15%-3.8%.In particular,a minimum pulse energy of 219 fj is experimentally detected with an average-power-peak-power product of 1.065×10^(-6)W^(2).The IJ-FPGA technology may offer a new route for miniaturized,user-friendly,and broadband pulsewidth measurement.