Fiber Loop Mirror Filter With Two-Stage High Birefringence Fibers

Abstract

Abstract-A fiber loop mirror (FLM) with two-stage high birefringence (Hi-Bi) fibers is theoretically and experimentally studied for various rotation angles and Hi-Bi fiber lengths. The experimental spectra are observed to be in good agreement with the theoretical spectra, verifying our theoretical model. The wavelength interval of the comb filter depends on the Hi-Bi fiber lengths and rotation angles. By varying the rotation angle from 0 • to 90 • , a comb-like transmission spectrum with small wavelength spacing is evolving into an exotic but periodic transmission spectrum and eventually become a larger wavelength spacing transmission spectrum. The FLM is useful in many applications such wavelength division multiplexing power equalization and management, switchable multi-wavelength fiber laser, optical switch and etc.

Characteristics of transverse-stress-induced phase change through a distinct dual-mode fiber in a Sagnac loop

“…These fields, upon recombining at the coupler, interfere, so as to give the output at the fiber ends. When the birefringence effect or polarization coupling occurs in the fiber, polarization non reciprocity in the Sagnac loop enables the configuration to sense the physical information, such as stress, temperature, pressure, and elongation [15][16][17][18][19].…”

Optical microphone based on Sagnac interferometer with polarization maintaining optical fibers

“…From the viewpoint of detection the useful is signal in arm D. The optical power of this signal describes an equation [4]:…”

“…Let's set E as horizontal linearly polarized optical signal in point A, which can be described as [4]:…”

“…Each orthogonal mode has different refractive index. After passing polarization maintaining fiber phases of modes can be described by the following forms [1][2][3][4]:…”

“…Transmittance function is written below in equation (4) for each arm. Optical isolator must be placed before laser to avoid unwanted noise [1][2][3][4]. Sagnac loop in configuration for optic microphone is made of PANDA-type polarization maintaining fiber.…”