Reflected intensity noise for laser diode to upside down tapered parabolic microlens on the circular core graded index fiber

Abstract The coupling reliability of laser-to-fiber coupling has become a significant concern in optical communication technologies. However, it appears that different categories of misalignment degrade the coupling efficiency (CE) when it comes to fiber-to-lens coupling. Unexpected noise gets generated by the lateral asymmetry because of back-reflection from the fiber endpoint to the laser diode (LD). In this article, we present an easily understood theoretical approach for determining the reflected intensity noise (RIN) when an LD is coupled to a graded index fiber (GIF) with an upside-down tapering parabolic microlens (UDTPML) on the fiber tip. We exhibit the RIN values concerning probable lateral alignment errors. The pertinent ABCD matrix has been applied to derive the relevant CE in the context of lateral misalignment. The findings will provide significant guidance for minimizing such noise in optical fiber couplers, leading to more efficient and reliable optical technology. Further, the study not only meets the current demands of high-speed data transmission but also paves the way for future advancements in optical technology.