  We have developed and characterised a stable, narrow linewidth
external-cavity laser (ECL) tunable over 100 nm around 1080 nm, using a
single-angled-facet gain chip. We propose the ECL as a low-cost,
high-performance alternative to fibre and diode lasers in this wavelength range
and demonstrate its capability through the spectroscopy of metastable helium.
Within the coarse tuning range, the wavelength can be continuously tuned over
30 pm (7.8 GHz) without mode-hopping and modulated with bandwidths up to 3 kHz
(piezo) and 37(3) kHz (current). The spectral linewidth of the free-running ECL
was measured to be 22(2) kHz (Gaussian) and 4.2(3) kHz (Lorentzian) over 22.5
ms, while a long-term frequency stability better than 40(20) kHz over 11 hours
was observed when locked to an atomic reference.
