  A low noise linearly frequency modulated continuous wave laser source with a
wide frequency bandwidth is demonstrated. By two-dimensional thermal tuning,
the laser source shows 42 GHz continuous frequency tuning with 49.86 Hz
intrinsic linewidth under static operation. For dynamical FMCW, the laser
source has 10.25 GHz frequency bandwidth at 100 Hz chirped frequency and 5.56
GHz at 1 kHz chirped frequency. With pre-distortion linearization, it can
distinguish 3 m length difference at 45 km distance in the fibre length
measured experiment, which demonstrate a potential for application in
ultra-long fibre sensing and FMCW LiDAR.
