Study of asymmetric biconical fiber tapers for in-fiber Mach-Zehnder interferometers and applications in single-frequency fiber lasers

Abstract

In this paper, asymmetric biconical fiber tapers (ABFTs) for in-fiber Mach-Zehnder interferometers (IFMZIs) are proposed and analyzed to enhance the interference effect. The proposed ABFT-IFMZIs are fabricated, tested, and demonstrated in applications of single-frequency (SF) emissions when incorporated into an all-fiber laser cavity as the frequency selecting component. In comparison with the traditional IFMZIs composed of all symmetric biconical fiber tapers (SBFTs), higher average transmittance and fringe contrast have been demonstrated with the ABFT-based IFMZIs. When applied to the SF fiber laser emission, lower pump threshold and higher slope efficiency have also been confirmed with the ABFT-IFMZI device. The theoretical and experimental results have indicated that the interference effect of IFMZIs can indeed be improved by the designated asymmetry of conical taper angles in ABFTs that can offer an extra flexibility in fiber taper design, fabrication, and applications.

Fiber Ring Laser Based on Side-Polished Fiber MZI for Enhancing Refractive Index and Torsion Measurement

“…There is a phase difference between the core and the cladding within the sandwiched SMF. The MZI interference phase difference caused by the optical path difference between the core and cladding modes can be described by [4]:…”

“…n recent years, tunable erbium-doped fiber ring lasers have been comprehensively studied due to their great potential in space communication and fiber sensing [1]. The in-fiber Mach-Zehnder interferometer (MZI), which is composed of two interference arms integrated in an optical fiber, is widely used in optical fiber sensor, optical filter and optical fiber communication [2][3][4]. Therefore, researchers recently proposed to combine the erbium-doped ring cavity laser with the in-fiber MZI to construct a fiber laser sensor based on the in-fiber MZI [5][6][7].…”