The periodical pulse bundles were presented in a Yb-doped double-clad distributed Bragg reflector all-fiber configuration. With a pumped power of 529.2 mW, the periodical pulse bundles is obtained. Furthermore, a single pulse bundle composes of one main pulse and two sub-pulses. The pulse width of the main pulse and the sub-pulse are 2.2 μs and 7.7 μs, respectively. The separations of between main pulse, right sub-pulse and left are 22.70 μs and 22.15 μs, respectively. The average period of the pulse bundle is approximately 75 μs with repetition rate of 13.3 kHz. The number of sub-pulses between adjacent main pulses decreases to one when the pumped power does to 450.2mW. When the pumped power increases to 594.4 mW, the number goes to three.
A Ho3+-doped photonic crystal fiber laser with output wavelength of 2077nm has been demonstrated using a 1992nm Tm3+-doped fiber laser with output wavelength of 1992nm as a pump source. And the optical- optical conversion slope efficiency is 41.3%. In order to optimize the output power of the Ho3+-doped photonic crystal fiber laser, a simple quasi-three level system theoretical modeling is developed in the condition of Stark-splitted energy level diagram of holmium ion. We obtain the theoretical optical- optical conversion slope efficiency 43.5%, which is higher than the experimental 41.3%. Furthermore, the relative deviation of the η is 5%, which shows the theoretical data is good agreement with experimental data. According to the modeling, the influence factors of the output power have been theoretically studied, in detail. The results show that there are an optimal range of Ho3+-doped concentration n0, transmittance of coupled output mirror T2 and length of the PCF L, respectively. Furthermore, the output power is approximately equal to maximum in the range of the optimal value.
In this paper, we present a theoretical model to describe the passively-Q output characteristics of quasi-three level Ho3+-doped Fluorotellurite fiber lasers. According to the model, we have studied the factors impacting on the output characteristics of the laser through numerical simulation method. The calculating program of the theoretical model is written using the Matlab language. We obtain the passively-Q output laser with the pulse repetition rate of 13.1 kHz, pulse width of 28.63ns, peak power of 25W, and pulse energy of 0.34 μJ at the pump power of 0.1W. When the pump power increases, the pulse width of the laser decreases, the pulse repetition rate linearly increases, both the pulse energy and the peak power also increases. The pulse width of the laser linearly increases and the pulse energy increases when the length L does. When the output coupler transmission T increases, both the pulse width and the peak power of the laser decrease. The pulse energy of the laser firstly increases and then decreases when the output coupler transmission T does. We qualitatively analyze what causes the change laws of the outputlaser characteristics, such as the pulse width and the pulse energy.
16-core photonic crystal fiber (PCF) was designed. In order to obtain spatially flat in-phase modes, the super-mode near- field properties were studied through method of numerical simulation calculation and according to coupled mode theory. On the based of the scalar Fraunhofer Diffraction, a far- field in-phase super-mode theoretical modeling was presented. According to the modeling, one discussed the influence of the random phase perturbation, the random amplitude perturbation and the polarization direction perturbation on the far-filed intensity distribution, in detail. The results show that both phase perturbation and amplitude perturbation sharply impact the far-filed distribution of interference intensity and contrast. However, the influence of the polarization direction perturbation is not obvious. When the parameterδ, μ and ▵ increases, the field center intensity decreases and the power of the central spot also does, which means the profile of the spot will blur and the beam quality drop.
An intracavity optical parametric oscillator (IOPO) pumped by a continuous-wave (CW) mode-locked laser is experimentally realized. The fundamental cavity and optical parametric oscillator cavity are designed to satisfy synchronous pumping. The output characteristics of signal and idle light are measured. Because of higher fundamental photon intensity in IOPO, the threshold of IOPO is lower than that of an extra-cavity optical parametric oscillator. The spectroscopy of signal light is obtained and the wavelength of idle light can be estimated to be 3.298 μm from noncritical phase matching. Based on the intensity fluctuation mechanism of fundamental locking, the dynamical model for IOPO pumped by a CW mode-locked laser is developed. The simulated results for the temporal shape of three lights are calculated from the derived rate equations. Because of dispersion, the signal pulse width of the theory is smaller than that of the experiment with the same pump energy.
In order to investigate the power characteristics of the Yb-doped photonic crystal fiber(PCF) laser, we have represented a simple three-level system modeling based on a rate equation model. According to our theoretical modeling, the variation of the output power Pout via the pump power Pp is theoretically studied, which agrees well with experimental data. Then, we have investigated the effects of the doped concentration of Yb ions, the length and the effective mode field area of the PCF on the output power Pout of the Yb-doped PCF laser, respectively. The results show that the output power Pout first increases and then decreases when the doped concentration of Yb ions N0 increases and when the pump power Pp and the length of the PCF L are constant. And the optimal doped concentration Nm exponentially decreases when the length L of the PCF increases and the slope of the optimal doped concentration Nm also decreases when the length L of the PCF increases. The output power Pout first increases and then decreases when the length of the PCF L increases and when the pump power Pp and the doped concentration N0 are constant. And the optimal length Lm of the PCF exponentially decreases when the doped concentration N0 increases and the slope of the length of the PCF also decreases when the doped concentration N0 increases. The output power Pout linearly decreases when the effective mode field area A increases.
One provides a simple recipe, which is manipulating refractive of doped region of the MCPCF, to obtain the equal
amplitude distribution of the in-phase supermode for multicores photonic crystal fibers (MCPCFs). Using coupled mode theory and vector finite element method (VFEM), a 7-core PCF is analyzed in detail and the results are applied to 16-,18- and 19-core PCFs, which will find important applications in high-power MCPCF lasers and amplifiers. One shows that it is possible to construct uniformly distributed modes for the nontrivial examples of 7- 16-, 18- and 19-core PCFs. One demonstrates that an equal amplitude distribution of in-phase supermode can be achieved by manipulating refractive of doped region in cores area. This research would provide a theoretical basis for investigating equal amplitude in-phase supermode in the MCPCF.
A photonic crystal fiber-based localized surface Plasmon resonance sensor with supermodes is analyzed. In the
boundary condition of anisotropic perfectly matched layer (PML), a full-vector finite element method (FEM)is used to
calculate the fiber model. Numerical results indicate that the excitation of the plasmon mode is sensitive to the change of
the refractive index of adjacent analyte. The maximum amplitude sensitivity of the fiber sensor is 1124dB/RIU. Its
resolution can reach 4×10-5 RIU. The maximum spectral sensitivity of the sensor can be about 2000nm/RIU. Its
resolution can reach 5×10-6 RIU.
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