The invention concerns a semiconductor electro-optical monolithic component comprising successively a first section (30) designed to emit light at a first wavelength and including a first active layer (31), a second section (40) designed to absorb light at said first wavelength and including a second active layer (41), and a third section (20) designed to detect light at a second wavelength and including a third active layer (21). The invention is characterized in that the second active layer (41) is designed to ensure in said second section (40) an absorption higher than that which would be allowed by an active layer identical to the first layer (31).
