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981.
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986.
A widely tunable narrow linewidth compact erbium-doped all-fiber ring laser with 104 nm tuning range was reported. An all-fiber
Fabry-Perot filter (FFP-TF) was used to realize the laser tuning output, and the wavelength at constant voltage had high time
stability. With the 8 m length erbium-doped fiber as gain medium, we realized widely tunable laser from 1513 to 1617 nm with
the linewidth less than 40 pm at any wavelength. Pumped by the 976 nm laser diode, the fiber laser worked with slope efficiency
of above 10% and threshold of less than 21 mW. 相似文献
987.
A high stability all-fiber LD-clad-pumped Tm3+-doped fiber laser was reported. The fiber laser had the ultra-narrow linewidth 50 pm at 1.948 μm with the maximal output
power of 12.8 W. The slope efficiency was 28.9%, and threshold was 5.7 W. The double-clad Tm3+-doped fiber core was multi-mode, which had a demission of 25/250 μm with the core NA of 0.1 and inner-clad NA of 0.46. The
high reflectivity coupler FBG was directly written into the single-mode passive photosensitive optical fiber core, which had
a core diameter of 15 μm and NA of 0.1. The cavity was build-up by the high reflectivity FBG and the output fiber end Fresnel
reflectivity. 相似文献
988.
By employing the fixed point theorem of cone expansion and compression of norm type, we investigate the existence of positive solutions of generalized Sturm-Liouville boundary value problems for a nonlinear singular differential equation with a parameter. Some sufficient conditions for the existence of positive solutions are established. In the last section, an example is presented to illustrate the applications of our main results. 相似文献
989.
In this note,we obtain some a-priori estimates for gradient of weak solutions to a class of subelliptic quasilinear equations constructed by Ho¨rmander’s vector fields,and then prove local uniqueness of weak solutions.A key ingredient is the estimated about kernel on metirc "annulus". 相似文献
990.
On the basis of the electromagnetic response of high frequency relic gravitational waves (HFRGWs), we research on more accurate calculation of signal (i.e. transverse perturbative photon flux (PPF)) and background photons flux (BPF) in the sycro-resonance electromagnetic system, which consists of Gaussian beam (GB), a static magnetic field and fractal membranes. According to the relationship between frequency of gravitational waves and its dimensionless amplitude, we focus on the HFRGWs with ν g = 2.9 GHz, h ~ 10?30 in the pre-big bang and quintessential inflationary models. The results show the peak value of the transverse BPF (~ 1020 s?1) is around |x| = 0.08 m, where |x| is the transverse distance to the longitudinal symmetrical surface of the GB, while the maximum transverse PPF always appears at x = 0 (\({N^{(1)}_{x} \sim 2.60\times10^{2}\,{\rm s}^{-1}}\) with the optimal phase difference between the GB and the resonant component of the HFRGWs δ = (n + 0.9)π, n = 0, 1, 2 . . .). However, the observable PPF should be ~ 1.19 × 102 s?1 because of the stochastic nature of the HFRGWs’ phase. Since the decay speed of BPF is much quicker than PPF, it is hopeful to figure out the signal in some optimal regions. Moreover, we compare the decay speed of BPF and PPF in nature mode, and find the threshold value of x where PPF exceeds to BPF. It demonstrates that the limitation of our detection sensitivity comes from the strength of PPF rather than swamping by BPF. On the other hand, with the fractal membrane, the comparison between BPF and PPF provides the optimal detection area \({x\in[0.28,1]}\) m. In addition, through the calculation of shot noise and conservative estimation, we find that our sensitivity is h = 10?26 in 4 months signal accumulate time. 相似文献