W-type barium ferrites doped with Gd^3＋,Ba1-xGdx（Zn0.3Co0.7）2Fe16O27（x = 0,0.05,0.10,0.15,0.20）,were prepared by a sol-gel method.The effects of Gd^3＋ substitution on their microstructure,electromagnetic propert...W-type barium ferrites doped with Gd^3＋,Ba1-xGdx（Zn0.3Co0.7）2Fe16O27（x = 0,0.05,0.10,0.15,0.20）,were prepared by a sol-gel method.The effects of Gd^3＋ substitution on their microstructure,electromagnetic properties and microwave absorptive behavior were analyzed.The XRD patterns showed the single phase of W-type barium ferrite when x ≤ 0.15.Microwave electromagnetic properties of samples were studied at the frequency range from 2 GHz to 18 GHz using a network analyzer（Agilent 8722ET）.The complex permittivity ε（ε＇,ε＇＇） increased gradually when x ≤ 0.10,but it decreased as x = 0.15.The real permeability（μ＇） decreased with the increase of Gd^3＋ content,while the imaginary permeability（μ＇＇） increased when x ≤ 0.10.All these reasons were discussed using the electromagnetic theory.Furthermore,the ferrite-epoxy compound coating materials with 80 wt.% of Ba0.9Gd0.1（Zn0.3Co0.7）2Fe16O27 were prepared to measure the microwave absorbing properties.The maximum of reflection loss（RL） reached about-27 dB and RL was below-10 dB in the frequency range of 8-18 GHz when the thickness was 1.92 mm.展开更多
A high-efficiency eye-safe Raman laser was demonstrated by use of the third Stokes radiation in a Ba（NO3）2 crystal pumped by a 1064-nm Nd：YAG laser. The output wavelength of the Raman laser was 1598.5 nm with a ful...A high-efficiency eye-safe Raman laser was demonstrated by use of the third Stokes radiation in a Ba（NO3）2 crystal pumped by a 1064-nm Nd：YAG laser. The output wavelength of the Raman laser was 1598.5 nm with a full-width at half-maximum （FWHM） of 1.5 nm. With an incident pump energy of 140 mJ, a maximum of 18-mJ Raman output energy was generated at a repetition rate of 30 Hz, corresponding to an optical-to-optical conversion efficiency of 12.9%. The Raman pulse duration was shortened to 2.9 ns compared with that of the pump pulse of 19.3 ns. The eye-safe solid-state Raman laser is expected to have wide applications in range-finding, telemetry, laser radar, and other aspects.展开更多
We demonstrate wavelength-selectable visible emissions from a miniature crystalline laser that combines the stimulated Raman scattering （SRS） effect in an Nd：YVO4 crystal with intracavity frequency mixing in an ang...We demonstrate wavelength-selectable visible emissions from a miniature crystalline laser that combines the stimulated Raman scattering （SRS） effect in an Nd：YVO4 crystal with intracavity frequency mixing in an angle-tuned beta barium borate （BBO） crystal. The presented laser is operating on demand at any one of three wavelengths in the green-yellow spectral region. Up to 600, 560, and 200 mW output powers at 559, 532, and 588 nm, respectively, are obtained from the continuous wave （CW） laser having a 18 mm long resonator and a 3.8 W laser diode end pumping. The pump threshold for each visible wavelength is less than 0.4 W.展开更多
基金supported by the Pre-research Foundation of CPLA General Equipment Department (NO.9140A××××6401)
文摘W-type barium ferrites doped with Gd^3＋,Ba1-xGdx（Zn0.3Co0.7）2Fe16O27（x = 0,0.05,0.10,0.15,0.20）,were prepared by a sol-gel method.The effects of Gd^3＋ substitution on their microstructure,electromagnetic properties and microwave absorptive behavior were analyzed.The XRD patterns showed the single phase of W-type barium ferrite when x ≤ 0.15.Microwave electromagnetic properties of samples were studied at the frequency range from 2 GHz to 18 GHz using a network analyzer（Agilent 8722ET）.The complex permittivity ε（ε＇,ε＇＇） increased gradually when x ≤ 0.10,but it decreased as x = 0.15.The real permeability（μ＇） decreased with the increase of Gd^3＋ content,while the imaginary permeability（μ＇＇） increased when x ≤ 0.10.All these reasons were discussed using the electromagnetic theory.Furthermore,the ferrite-epoxy compound coating materials with 80 wt.% of Ba0.9Gd0.1（Zn0.3Co0.7）2Fe16O27 were prepared to measure the microwave absorbing properties.The maximum of reflection loss（RL） reached about-27 dB and RL was below-10 dB in the frequency range of 8-18 GHz when the thickness was 1.92 mm.
基金This work was supported by the National High Technology Project (No. 2004AA846020) and the National Natural Science Foundation of China (No. 10334110).
文摘A high-efficiency eye-safe Raman laser was demonstrated by use of the third Stokes radiation in a Ba（NO3）2 crystal pumped by a 1064-nm Nd：YAG laser. The output wavelength of the Raman laser was 1598.5 nm with a full-width at half-maximum （FWHM） of 1.5 nm. With an incident pump energy of 140 mJ, a maximum of 18-mJ Raman output energy was generated at a repetition rate of 30 Hz, corresponding to an optical-to-optical conversion efficiency of 12.9%. The Raman pulse duration was shortened to 2.9 ns compared with that of the pump pulse of 19.3 ns. The eye-safe solid-state Raman laser is expected to have wide applications in range-finding, telemetry, laser radar, and other aspects.
文摘We demonstrate wavelength-selectable visible emissions from a miniature crystalline laser that combines the stimulated Raman scattering （SRS） effect in an Nd：YVO4 crystal with intracavity frequency mixing in an angle-tuned beta barium borate （BBO） crystal. The presented laser is operating on demand at any one of three wavelengths in the green-yellow spectral region. Up to 600, 560, and 200 mW output powers at 559, 532, and 588 nm, respectively, are obtained from the continuous wave （CW） laser having a 18 mm long resonator and a 3.8 W laser diode end pumping. The pump threshold for each visible wavelength is less than 0.4 W.
