GaN laser diodes have the potential to be a key enabling technology since the AlGaInN material system allows for laser diodes to be fabricated over a wide range of wavelengths from the u.v. to the visible. Novel applications include high power laser bars for optical pumping, to laser sources for quantum technologies based on atom interferometry, such as next generation optical clocks and gravity sensors. We report our latest results on a range of AlGaInN diode-lasers targeted to meet the linewidth, wavelength and power requirements suitable for optical clocks and atom interferometry systems. This includes the [5s2S1/2-5p2P1/2] cooling transition in strontium+ ion optical clocks at 422 nm, the [5s2 1S0-5p1P1] cooling transition in neutral strontium clocks at 461 nm and the [5s2s1/2 – 6p2P3/2] transition in rubidium at 420 nm. In addition, we report our latest results on tapered high power GaN laser diodes, for i) optical amplifiers, and ii) optimising the optical power of the device by reducing filamentation and hence avoiding catastrophic optical mirror damage (COMD).