Patent ID: 7062178

Claim:
A light-receiving element array for receiving light beams demultiplexed for each wavelength from a wavelength multiplexed light beam and arranged in a straight line, wavelengths from the wavelength multiplexed light beam corresponding to respective channels, comprising: a plurality of light-receiving elements for monitoring signals for each of the respective channels, and a plurality of light-receiving elements for monitoring noises for each of the respective channels, wherein the light-receiving elements for monitoring signals and the light-receiving elements for monitoring noises are alternately arrayed in a straight line, a direction thereof being the same as that of an arrangement of the demultiplexed light beams, and wherein the light-receiving elements for monitoring noises are positioned relative to the light-receiving elements for monitoring signals such that a signal shift of a monitored signal results in the monitored signal being received concurrently by one of the light-receiving elements for monitoring signals and by one of the light-receiving elements for monitoring noises.