Optical signal processing apparatus

#1. Field of the Invention

#The present invention relates to an optical signal processing apparatus which multiplexes or demultiplexes signal light with multiple wavelengths.

#2. Related Background Art

#FIG. 1A is a view showing the arrangement of an optical signal processing apparatus 1 according to the first embodiment when viewed in parallel to the z-axis direction;

#FIG. 1B is a view showing the arrangement of the optical signal processing apparatus 1 according to the first embodiment when viewed in parallel to the y-axis direction;

#FIG. 2A is a view showing the azimuth of the plane of polarization and optical path at each position of signal light in the optical signal processing apparatus 1 according to the first embodiment when the rotation angle θ of the plane of polarization of signal light having a wavelength λ4, which passes through a Faraday rotation element 34, is 0, and the polarized light component of the signal light that is input to the Faraday rotation element 34 has the first azimuth;

#The embodiments of the present invention will be described below in detail with reference to the accompanying drawings. The same reference numerals denote the same elements throughout the drawings, and a repetitive description thereof will be omitted.

#(First Embodiment)

#An optical signal processing apparatus according to the first embodiment of the present invention will be described first. FIGS. 1A and 1B are views showing the arrangement of an optical signal processing apparatus 1 according to the first embodiment. FIGS. 1A and 1B show an x-y-z Cartesian coordinate system for the descriptive convenience. FIG. 1A shows the arrangement viewed in parallel to the z-axis direction. FIG. 1B shows the arrangement viewed in parallel to the y-axis direction. The optical signal processing apparatus 1 shown in FIGS. 1A and 1B can be used as a 4-channel optical multiplexer/demultiplexer. Each of four wavelengths λ1 to λ4 input from a first port P1 (an end face of an optical fiber 81) is output from one of a second port P2 (an end face of an optical fiber 82) and a third port P3 (an end face of an optical fiber 83). In addition, signal light components of respective wavelengths input to the second port P2 or third port P3 are output from the first port P1.