ADD-DROP MULTIPLEXING/DEMULTIPLEXING MODULE

摘要

PROBLEM TO BE SOLVED: To reduce the size and cost of an add-drop multiplexing/demultiplexing module. SOLUTION: A first separating and synthesizing birefringent element 20 which separates the light of the same optical paths having polarization directions in an orthogonal relation ad synthesizes the light of the different optical paths, first and second birefringent elements 21 and 22 for optical path control which control the optical paths according to the polarization directions and a second separating and synthesizing birefringent element 23 are disposed apart spaced intervals in this order. First and second polarization rotation means 24 and 27 which convert the polarization directions from orthogonal to parallel or from parallel to orthogonal are arranged between the separating and synthesizing birefringent elements and the birefringent elements for optical path control. A 45 deg. Faraday rotator 31, a band-pass filter 32 which allows the transmission of the wavelength of add-drop light and reflects the wavelength light exclusive thereof and a 45 deg. Faraday rotator 33 are arranged between both birefringent elements for optical path control. An input port and output port are installed to one of these arrays and a drop port and add port are installed to the other.