Reconstruction of 3D refractive index profiles of PM PANDA optical fiber using digital holographic method

• The refractive indices distributions at the two birefringent axes of PM PANDA optical fiber are reconstructed.
• The birefringence and the beat length in fast and slow axes of PM optical fiber in the core region are calculated.
• Reconstruction of the 3D refractive index distributions for PM PANDA optical fiber.
• Off-axis digital holographic interferometric phase shifting method.

In this paper, the refractive indices distributions on the two birefringent axes of polarization maintaining (PM) PANDA type optical fiber are reconstructed. The local refraction of the incident rays crossing the PM optical fiber is considered. Off-axis digital holographic interferometric phase shifting arrangement is employed in this investigation. The recorded mutual phase shifted holograms, starts with 0° with steps of π/4, are combined and numerically reconstructed in the image plane to obtain the optical interference phase map. Consequently, the optical phase differences due to the PM optical fiber are extracted after unwrapping and background subtraction of the enhanced optical interference phase map. The birefringence and the beat length in the two directions, fast and slow axes of PM optical fiber, of polarizations in the core region are calculated. This holographic technique and the advanced analysis of the phase shifting permit the calculation of the 3D refractive index distributions for PM PANDA optical fiber.