Reflected intensity noise for laser diode to cylindrical microlens on the elliptical core step index fiber

Abstract

The trustworthiness of the laser-to-fiber coupling is one of the main issues in optical communication technology. However, various types of misalignment lower the coupling efficiency (CE) in fiber-to-lens coupling. The lateral asymmetry also results in an unexpected noise owing to the rear reflection from the fiber terminal to the laser diode (LD). In the present paper, a simple theoretical approach is presented to calculate the reflected intensity noise (RIN) in an LD attached with a single mode elliptical core step index fiber (SMECSIF) through a cylindrical microlens (CML) on the tip of the fiber. We present RIN values for such a coupling device. For the case of lateral misalignment, the corresponding CE has been obtained by using ABCD matrix. Using this, the findings will give valuable guidance for the reduction of noise in optical fiber couplers, thereby improving the efficiency and reliability of optical technology. In addition, the study caters the present need for transfer of data with large velocity and facilitates future developments in optical engineering.