Wenning Jiang

Robust, compact, and flexible neural model for a fiber Raman amplifier

In this paper, a novel robust, compact, and flexible neural-network model for a fiber Raman amplifier (FRA) is presented. The model can be used in various applications with promising accuracy and low requirement for memory. Analytical expressions are derived in order to make the optimal pump-power configuration much easier, and the computational time is reduced dramatically in comparison with other gain-design methods in real-time pump-power adjustment. The calculated on-off gain spectrum and the noise figure using the proposed model agree well with the experimental results. The model has a potential value in simulation and pump-power dynamic control.

Modal Interferometer Based on a C-Shaped Ultrathin Fiber Taper for High-Sensitivity Refractive Index Measurement

The ultrathin fiber taper fabricated by adiabatically stretching a heated single-mode optical fiber (SMF) is made in a C-shape bent to form a modal interferometer. The interference fringes due to the mode beating in the multimode taper waist are dependent on the bending radius. Under an optimized bending radius, a maximum 18 dB interference depth can be obtained. The influence of the fiber taper geometry on the interference fringes is discussed. The proposed modal interferometer has a high refractive index (RI) sensitivity of ~658 nm/RIU (refractive index unit) for RI= 1.333–1.353, which is expected to be useful for precision bio/chemical sensing applications.

A novel algorithm for a multi-cavity Raman fiber laser

In this paper a Raman Fiber Lasers (RFLs) with several embedded cavities are studied. A novel algorithm is proposed to solve the coupled equations describing the optical power evolution in a RFL. By using some invariant constants as the boundary condition at the output end, the problem of solving ordinary differential equations (ODEs) with guessing boundary value is translated into a two-boundary-condition ODE problem. The algorithm is based on Newton-Raphson method and proved rather fast and stable. Quantitative analysis is performed based on the algorithm.

Raman induced polarization dependent gain in orthogonally pumped parametric amplifiers

In this paper, Raman induced polarization dependent gain (PDG) in orthogonally pumped optical parametric amplifiers is investigated. Based on the Manakov Eqs., complete coupled Eqs. are derived and numerically solved. Analytical approximate solutions are derived. The simulation results show that in orthogonally pumped optical parametric amplifiers, the Raman effect between the pump and the signal contributes more prominently to the PDG than that induced by asymmetrical pump depletion.

Characterized Brillouin scattering in silica optical fiber tapers based on Brillouin optical correlation domain analysis

This paper demonstrates stimulated Brillouin scattering (SBS) characterization in silica optical fiber tapers drawn from commercial single mode optical fibers by hydrogen flame. They have different waist diameters downscaled from 5 μm to 42 μm. The fully-distributed SBS measurement along the fiber tapers is implemented by Brillouin optical correlation domain analysis technique with millimeter spatial resolution. It is found that the Brillouin frequency shift (BFS) in the waist of all fiber tapers is approximately the same (i.e., ~11.17 GHz at 1550 nm). However, the BFS is gradually reduced and the Brillouin gain decreases from the waist to the untapered zone in each fiber taper.

A Novel Algorithm for Backward-Pumped Raman Amplifier

In this article, a novel semi-analytical algorithm for calculating backward-pumped Raman amplifier is proposed. The algorithm does not need iteration and can greatly save computational time. Simulation results for Raman amplifiers with 25 km, 50 km, and 100 km fibers show that the accuracy of the method is quite satisfying in comparison with the shooting algorithm and the deviation is within 0.02 dB.

Tracing photon transmission in dye-doped DNA-CTMA optical nanofibers

We experimentally demonstrate the novel phenomena of photoluminescence (PL) and fluorescence resonance energy transfer (FRET) assisted three-color PL separating in DNA optical nanofibers consisting of the stretched and connected DNA-cetyltrimethyl ammonium wires. The PL experiments are performed to comparatively trace photon transmission between single dye-doped DNA-CTMA optical nanofiber and PMMA optical nanofiber. A cascade FRET including DNA minor groove binder and DNA intercalators is used to further trace photon transmission inside DNA-CTMA wire. These experimental results will help to intrigue the new applications of DNA-CTMA as molecular waveguide in optobioelectronics area.

Performance improvement of fiber Raman amplifiers using time-division-multiplexed pumping

A novel kind of optical fiber Raman amplifiers using time-division-multiplexed (TDM) pumping is analyzed. The equations governing the evolution of the pumps and signals are presented for both TDM forward and TDM backward pumping. Simulation results show that the performance in gain profile and ASE noise figure can be effectively improved. The optimal TDM pump repetition rates are between 2 and 8 MHz.

Frequency domain model to calculate the pump to signal RIN transfer in multi-pump Raman fiber amplifiers

In this paper, a novel frequency domain model to compute the pump to signal relative intensity noise (RIN) transfer in multi-pump Raman fiber amplifiers (RFAs) is proposed. The analytical expressions for RFAs with single pump and single signal channel are derived as a specific case of the model. The formulas exactly agree with the published results both for the co-pumped and counter-pumped RFAs. Afterwards, the pump to signal RIN transfer in multi-pump RFAs is studied numerically with thorough discussions.

Optimal Position of Isolator to Suppress Double Rayleigh Backscattering Noise in Fiber Raman Amplifiers

In this paper, amplified double Rayleigh backscattering noise (DRB) in the optical fiber Raman amplifier is analyzed. Expressions are present for both forward pumping and backward pumping schemes, respectively. Calculation is performed to show the effective suppression of DRB noise by employing an optical isolator. The best isolator position is determined as 13 km away from the signal input end for forward pumping, and 9 km from the output end for backward pumping. The best position is found insensitive to the fiber length, pump power, and signal power. When the isolator is on the best position, the DRB noise can be reduced by almost 2 to 3 orders.