Measurement of the thickness of side-polished fiber based on digital holography

A novel method to measure the remaining cladding thickness of side-polished fiber (SPF) was demonstrated by using the digital holography technology. By using angular spectrum method and accurate least-squares phase unwrapping method, the phase distribution of SPF could be reconstructed. Based on the reconstructed phase distribution, the remaining cladding thickness of SPF could be directly measured. It can reduce the errors due to fiber’s asymmetries and edge diffraction. This method could also be used to measure other special optical fibers such as photonic crystal fiber and nano-fiber.