Designing high performance Er+3-doped fiber amplifier in triangular-lattice photonic crystal fiber host towards higher gain, low splice loss

In order to improve the over-all performance of all-fiber amplifier using Er+3-doped triangular-lattice photonic crystal fiber (PCF), we performed a detailed study on the amplifying characteristics of the PCF host by varying all associated geometrical parameters towards utilizing controllable effective numerical aperture and tight modal confinement. A finite difference (FD) mode convergence analysis is used to determine the modal propagation characteristics of the structure, which is then used to solve a standard propagation and population rate equation. Our results show that a spectral gain of the amplifier as high as 51 dB and that too over a short length ∼2.5 m of the fiber is achievable by optimizing the transverse geometry of the fiber. Aimed at field-deployment of the amplifier as inline component, we calculate the important all-fiber characteristics, namely, beam divergence, bending loss and nonlinearity and then optimize the splicing/coupling loss (resulting from the fundamental mode mismatch only) of this active fiber device. Notably, the splice loss with standard telecom-grade SMF-28 fiber is considerably minimized through an improved mode-matching of the design. These results record a marked improvement in fiber amplifier research in realizing high-performance EDFA-PCF amplifiers.

► We perform a detailed design analysis of the photonic crystal fiber amplifier. ► We use the finite difference mode convergence algorithm for analysis of the PCF mode. ► Dependence of amplifier gain on several parameters is discussed. ► Optimum amplifier geometry yields high gain above 51 dB. ► Splice loss of our proposed fiber with standard single-mode fiber is also minimized.