US Patent 7369585 Semiconductor based broad area optical amplifier

An optical amplifier including: a photonic gain clement; and, a transistor electromagnetically coupled to the gain element to inject current into the gain element responsively to the internal optical intensity of the gain element. The coupling of the transistor and the photonic gain element is such that as the optical intensity within the photonic gain element increases, the current injected by the transistor increases, thereby preventing filamentation in the photonic gain element.