A Simple but Accurate Method for Prediction of Reflected Intensity Noise for Single-Mode Circular Core Triangular Index Fiber Excitation via Upside Down Tapered Hemispherical Microlens on the Tip of Fiber

Abstract

AbstractIn optical communication system, the coupling efficiency relating to laser to fiber coupling emerges as an important topic. But it is found that misalignment in the context of fiber to lens coupling reduces the coupling efficiency. The lateral mismatch leads to generation of unwanted noise owing to back-reflection from fiber end to laser diode. Here, we report a simplified theoretical method for estimating the reflected intensity noise (RIN) in case of a laser diode to triangular type index fiber coupling via upside down tapered hemispherical microlens on the corresponding fiber tip. We present RIN values as a function of possible lateral misalignments. The concerned coupling efficiency under the presence of lateral mismatch case has been formulated by applying relevant ABCD matrix. The results found shall prove to be beneficial to the system designers and engineers in the context of minimizing such noise in this coupler.KeywordsSingle-mode triangular index fiberUpside down tapered hemispherical microlensMisalignmentReflected intensity noise