DETECTING DEVICE FOR MULTIPLE WAVE LENGTH LIGHT

PURPOSE:To miniaturize and simplify a device by a method wherein a signal transmitted through photo-switch elements are sent via absorbing elements to light elements acting as a unity for emission of light. CONSTITUTION:Photo-switch elements 13, 14, and 15 of an n-i(n)-n structure, light emitting elements 18, 19, and 20 of an n-p-p strucrure, and light absorbing elements 17 are provided, with the light adsorbing elements 17 acting as an optical screen between the two structures. The component lengths of a light coming in from the left side are respectively received by the photo-switch elements; lambda1 by the layer 13, lambda2 by the layer 14, and lambda1 by the layer 15. When the photo-switch elements are in the conductive mode, the light emitting elements 18 through 20 communicate with each other via the absorbing elements 17, and minority carrier injection takes place causing emission of light. A received photo-signal containing a multiple number of light lengths thus can be converted into a set of separate photo-signals by using a single device.