In a laser-light source: submounts each being made of a material having a thermal expansion coefficient of 3.5 to 6.0.times.10.sup.-6/.degree. C. and having a thickness of 200 to 400 micrometers are separately formed on a heat-dissipation block made of copper or copper alloy; a single-cavity nitride-based semiconductor laser chips are respectively mounted junction-side-down on the corresponding submounts; an optical condenser system collects laser beams emitted from the semiconductor laser chips, and couples the collected laser beams to a multimode optical fiber. A bonding surface of each semiconductor laser chip is bonded to a bonding surface of a corresponding submount through a metalization layer and an Au--Sn eutectic solder layer each of which is divided into areas.