Compact tunable diode laser with diffraction limited 1 Watt for atom cooling and trapping

Since the introduction of laser-cooling techniques for neutral atoms, the enhancement of high-power lasers with excellent spectral and spatial quality has been an important research subject. We report a new principle of using highpower laserdiodes directly in an external cavity. The very compact design offers an output power of up to 1 W and an excellent beam quality (M² < 1.2). The coupling efficiency for a single mode fiber exceeds 60%. The center wavelength can be tuned between 775 nm and 785 nm. This laser operates single mode with a mode-hop free tuning range of up to 15 GHz without current modulation and a side-mode suppression better than 55 dB. Demonstrating the suitability forneutral atom cooling we used this laser as light source in the production of a BEC of over a million ⁸⁷Rb atoms.