An optical switch that routes optical signals without converting them into electrical signals is a key component used in optical fiber communications. It is required to exhibit low loss, low crosstalk, and low power consumption. A 1 × N arrayed-waveguide optical switch has an advantage whose circuit size is small. In a design of the 1 × N arrayed-waveguide optical switch, we employ some window functions other than a conventional Gaussian distribution. We show that slight modification of the optical power ratio between the arrayed-waveguides effectively suppresses the crosstalk to unrouted output ports.