Mode-locked fiber lasers at 1064 and 910 nm wavelengths using Nd^(3+)-doped silica fiber

Mode-locked lasing operations at 1064 and 910 nm wavelengths are demonstrated,respectively,in two all-fiber laser oscillators using our homemade Nd^(3+)-doped silica fiber(NDF)as the gain medium.The Al3+/Nd^(3+)co-doped silica core glass was fabricated by the modified sol-gel method with 18,300×10^(-6) Nd^(3+)doping concentration.The NDF drawn by the rodin-tube method has a core of 4μm in diameter and a numerical aperture(NA)of 0.14.At 1064 nm,we measure an average laser output power of 18mWwith a pulse duration of 5.75 ps,a pulse energy of 1.14 nJ,and a slope efficiency of 7.2%.Using the same NDF gain fiber of a different length,a maximum average laser output power is 3.1 mW at 910 nm with a pulse duration of 877 ns,a pulse energy of 2.7 nJ,and a slope efficiency of 1.44%.

Nd3+-doped silica glass and fiber prepared by modified sol-gel method

Large-size Al^(3+)/Nd^(3+)co-doped silica glass with 5000 ppm Nd^(3+)and 50,000 ppm Al^(3+)doping concentrations was prepared by the modified sol-gel method combined with high-temperature melting and molding technology.Electron probe microanalyzer tests indicated that high doping homogeneity was achieved with this sample preparation method.The spectral properties of the Nd^(3+)ions were evaluated.Nd^(3+)-doped silica fiber(NDF)with a core-to-clad ratio of 20/125μm was drawn from the preform with the Al^(3+)/Nd^(3+)co-doped silica glass as the core.In the laser oscillation experiment,a maximum output power of 14.6 W at 1.06μm with a slope efficiency of 39.6%was obtained from the NDF pumped by a commercial808 nm laser diode.To the best of our knowledge,this is the highest laser power reported for an NDF operated at 1060 nm and prepared by a non-chemical vapor deposition method.In the master oscillator power amplifier experiment,a maximum power of 16.6 W corresponding to a slope efficiency of 30.5%at 1061 nm was also demonstrated.The laser performance of the NDF exhibited the great advantages and potential of the modified sol-gel method in fabricating Nd^(3+)-doped silica glass for a new type of NDFs like large mode area fibers and fibers with large diameter ratio of core/cladding.

Colloidal(Gd0.98Nd0.02)2O3 nanothermometers operating in a cell culture medium within the first and second biological windows

Non-contact,self-referenced and near-infrared luminescent nanothermometers have been recognized as emerging tools in the fields of nanomedicine and nanotechnology due to their great capability of precise temperature readout at the nanoscale and real-time deep-tissue imaging.However,the development of multifunctional and biocompatible luminescent nanothermometers operating within the optically transparent biological windows with high thermal sensitivity(>2.0%/K)remains challenging.Here,we present(Gd0.98Nd0.02)2O3 nanothermometers operated effectively within the first and second biological windows upon continuous-wave laser diode excitation at 808 nm.Ratiometric thermometric parameters are defined by the relative changes in the emission intensities originating from the two Stark components of the 4 F3/2 level(R2 and R1)to the 4 I9/2(900-1000 nm),4 I11/2(1035-1155 nm)and 4 I13/2(1300-1450 nm)multiplets.The thermo metric parameters are evaluated for colloidal samples in a cell culture medium and powder samples,and the highest thermal sensitivity(2.18%/K at 298 K)is attained for the former in the first biological window(both the excitation and emission in the 800-965 nm range).The repeatability and temperature uncertainty are 99%and 1.2 K,respectively.The nanothermometers are biocompatible with human MNT-1 melanoma and HaCaT cells for 24 h of exposure and nanoparticle concentration up to 0.400 mg/mL,showing their potential for applications in nanomedicine,e.g.,intracellular imaging and temperature mapping.