25 kHz narrow spectral bandwidth of a wavelength tunable diode laser   with a short waveguide-based external cavity
  We report on the spectral properties of a diode laser with a tunable external cavity in integrated optics. Even though the external cavity is short compared to other small-bandwidth external cavity lasers, the spectral bandwidth of this tunable laser is as small as 25 kHz (FWHM), at a side-mode suppression ratio (SMSR) of 50 dB. Our laser is also able to access preset wavelengths in as little as 200 us and able to tune over the full telecom C-band (1530 nm - 1565 nm). 
R. M. Oldenbeuving, E. J. Klein, H. L. Offerhaus, C. J. Lee, H. Song   and K.-J. Boller
physics.optics