A Direct Diode Laser System Using a Planar Lightwave Circuit

Abstract

In this paper we propose a direct diode laser (DDL) system consisting of laser diode (LD) bars, a planar lightwave circuit (PLC), and an optical fiber. We have developed a PLC as an optical power combiner and an LD mounting technology that is suitable for coupling to the PLC. A DDL system is presented that consists of six LD-PLC optical modules for the laser-welding of highly heat-resistant plastics. The total output power is in the 200 W class, with a spot diameter of 5.52 mm for the major axis and 5.00 mm for the minor axis at a focal length of 50 mm. The total output efficiency is 60.9% from the laser diode to the welding torch.