SEMICONDUCTOR LASER ARRAY DEVICE

PURPOSE:To control laser beams independently by simple constitution, and to utilize monitor beams effectively by isolating a P-N junction and one part of a waveguide in a semiconductor laser chip by an isolation trench, forming a resonator on one side of the separation trench and shaping a photo-diode for receiving an optical output including the P-N junction on the other side. CONSTITUTION:When currents are caused to flow through P-N junctions including waveguides 2, 3 respectively shaped to a semiconductor laser chip 1 through electrodes 4', 5, a laser is oscillated between the edge face of a resonator in separation trenches 11, 12 and the edge face of a resonator in the semiconductor chip 1 in the waveguides 2, 3. Main laser beams are emitted from an upper end, and used as laser beams. Back beams emitted in the downward direction from the wall surfaces of the upper ends of the separation trenches 11, 12 are emitted into the separation trenches 11, 12, and received by the P-N junctions 15, 16. When a bias is applied previously among the electrodes 15, 16 and a rear electrode 17 so that a reverse bias is applied to the P-N junctions 15, 16 at that time, sections lower than the separation trenches 11, 12 function as photo-diodes, monitor currents proportional to laser beams can be extracted, and said sections lower than the separation trenches can be operated as the photo-diodes for monitor.