Abstract
The coupling characteristics of the optical fiber with a circular hollow pit is important in order to design a fiber device. The optical fiber with a circular hollow pit can separate x-polarization and y-polarization. The polarization splitter constructed from the optical fiber with a circular hollow pit can take out x-polarization and y-polarization separately due to the difference of coupling strengths of polarization. We propose a new polarization splitter. One-half of new polarization splitter is used for a depressed clad fiber and the half of new polarization splitter is used for the fiber with a circular hollow pit outside a core. When the width t/a1 of the depressed clad fiber is varied in the range 0.5≦t/a1≦3.0, the device length L and the bandwidth BW-15 at R≦-15dB (R: the extinction ratio) are investigated. It is found at t/a1=3.0 and Δ5=-0.322% that: (1) L takes its minimum value 3.24mm ; (2) BW-15 takes its maximum value 74.9nm.
