Micro-integrated high-power narrow-linewidth external-cavity tapered diode laser at 808  nm

A novel compact micro-integrated high-power narrow-linewidth external-cavity diode laser around 808 nm is demonstrated. The laser system contains a tapered amplifier consisting of a ridge-waveguide section and a tapered section with separated electrical contacts. Thus, the injection currents to both sections can be controlled independently. An external volume Bragg grating is utilized for spectral narrowing and stabilization. The diode laser system is integrated on a 5mm×13mm aluminum nitride micro-optical bench on a conduction cooled package mount with a footprint of 25mm×25mm. The diode laser system is characterized by measuring the output power and spectrum with the injection currents to the ridge-waveguide section (I_RW) and tapered amplifier section (I_TA) changed in steps of 25 and 50 mA, respectively. At I_RW=200mA and I_TA=6.0A, 3.5 W of output power is obtained with an emission spectral linewidth with an upper bound of 6 pm, and a beam propagation factor in the slow axis, M², of 2.6 (1/e²). The characterization of the temperature stabilization of the laser system shows an increase of the wavelength at a rate of 6.5 pm/K, typical for the applied volume Bragg grating.