<p>This work presents a study on developing optical isolators using Terbium Gallium Garnet (TGG) magnetic photonic crystal fiber (MPCF) that contains magnetic fluid (MF) in its air holes. Isolators utilize Faraday rotation (FR) to prevent reflections. When light travels parallel to a magnetic field, FR causes linearly polarized light to rotate. In the visible and infrared spectrum, TGG is a magneto-optical crystal with excellent performance. It features high thermal conductivity, low absorption, a high laser damage threshold, a high Verdet constant, and superior optical quality. Under a magnetic field, TE-TM mode conversion produces a non-reciprocal effect. Therefore, controlling Faraday rotation and modal birefringence is essential. Our study aims to modify these properties to enhance the non-reciprocal function of the proposed MPCF. This research introduces an MPCF structure based on TGG with air holes filled with different concentrations of magnetic fluids at various wavelengths. This design influences mode conversion, enabling numerical calculations of several parameters. Analysis reveals how wavelength impacts these parameters. The structure’s parameters are simulated, and Faraday rotation and modal birefringence are calculated by varying magnetic fluid concentrations and wavelengths. The results demonstrate improved magneto-optical (MO) characteristics, making the design suitable for constructing MO isolators.</p>