High-power, high-brightness semiconductor tapered diode lasers for the red and near infrared spectral range

The most promising concept to achieve high-output power together with a good beam quality is the tapered laser consisting of a straight ridge waveguide (RW) section and a tapered gain-region. The RW section should support only the fundamental guided mode and should suppress higher order modes. The taper angle has to be selected with respect to the lateral divergence of the beam propagating from the RW to the tapered section. High brightness tapered devices in the wavelength range between 635 nm and 1085 nm will be presented. For red emitting tapered lasers around 650 nm, the output power is limited to about 1 W due to the properties of the laser material. At this output power a beam propagation ratio M-2 of 1.3 and a brightness of 100 MW.cm(-2).sr(-1) will be shown. Devices made from laser structures with low vertical divergence down to 25 degrees (95% power included) without a significant deterioration of device parameters will be presented for the longer wavelength range near 1 mu m. For tapered lasers manufactured from these structures, nearly diffraction limited output powers larger than 10 W and a brightness of 1 GW.cm(-2).sr(-1) were measured.