Rectified Polarisation Coupling for Diode Laser Bars
Modern material processing with lasers has increased demands in terms of power and power density which cannot be obtained directly with diode lasers.
To improve the power density of diode laser bars a multi-step polarization coupling was developed. The beam quality of the combined beam then possesses the beam quality of the single bar while the output power is scaled up considerably.
For that a multitude of laser bars are inserted into individual resonators which share the last section in front of the outcoupling mirror. Through a clever choice of spectral filters all lasers run on individual but intertwined spectral combs of longitudinal laser modes. The reuslt is an increase in power by a factor of roughly 1.8 per coupling stage.
Powers in excess of 500W have be shown and future developments promise values well above 1kW.