| Title |
Simple Wavelength Control Structure of Polarization-Diversified-Loop-Based Fiber Comb Filter |
| Authors |
Do-Kyeong Kim ; Yong-Wook Lee |
| DOI |
http://dx.doi.org/10.5207/JIEIE.2017.31.5.008 |
| Keywords |
Fiber Comb Filters ; Polarization ; Polarization-Diversified Loop ; Wavelength Control |
| Abstract |
In this paper, we propose a simple filter structure that offers a wavelength tuning capability in a fiber comb filter based on a polarization-diversified loop (PDL). The proposed filter consists of a polarization beam splitter with four terminals for implementing the PDL, a combination of two waveplates, and polarization-maintaining fiber (PMF). The waveplate combination (WPC) includes three kinds of waveplate groups, namely, a group of two quarter-wave plates (QWPs), a set of a QWP and a half-wave plate (HWP), and a set of an HWP and a QWP. In the proposed filter, one end of PMF is connected to one port of the PBS so that its slow axis is oriented at 45° to the horizontal axis of the PBS. The other end of PMF is linked with the WPC set. In the proposed structure, the spectral evolution of output polarization was analyzed for eight input polarization states. The analytic transmittance of the filter was derived for the three WPC sets through the Jones matrix formulation. Through the theoretical calculation of transmission spectra, we prove that the proposed structure can realize the continuous wavelength tuning of the filter. |