| 摘要 |
<p>An array waveguide diffraction grating whose pass spectrum has a flat region of good flatness near the center wavelength. Straight waveguides (1) are connected to the outputs of light input waveguides (12). The width of each straight waveguide (1) is 0.65 times that of each light input waveguide (12). Taper waveguides (8) each for expanding the mode field of a signal light toward the output side are connected to the output side of the respective straight waveguides (1). A first slab waveguide (13), parallel array waveguides (14) having different lengths, a second slab waveguide (15), and parallel light output waveguides (16) are connected to the output side of the taper waveguides (8) in order of mention. The center of the power of the light signal propagated through the light input waveguides (12) is shifted to the center in the direction of the width by means of the straight waveguides (1) to input the center of the power of the light signal into the center in the direction of the width of the input end of the taper waveguides (8). Thereby the distortion of the mode field of the light outputted from the taper waveguides (8) is suppressed and a good flat region is created near the center wavelength of the pass spectrum.</p> |
