  We report a singly resonant continuous-wave optical parametric oscillator
(SRO), which is pumped by a semiconductor laser system and operates in the
mid-infrared region (2.9 to 3.6 {\mu}m). Fast tuning of the mid-infrared output
wavelength by more than 200 nm is demonstrated by scanning the pump laser
wavelength through only 1.25 nm, without any need to adjust the SRO settings.
The exceptionally large tuning range is obtained by choosing a pump wavelength
(780 nm) that corresponds to a turning point of the group velocity mismatch
between the phase-matched signal and idler waves of the SRO.
