Continuous scans of 8 GHz (the cavity mode spacing) can be achieved using the PZT alone, with even larger continuous scans expected with appropriate synchronous translation and rotation of the grating. The laser can also be tuned discontinuously over a range of about 20 nm around the free-running wavelength of the solitary laser diode by rotating the grating. This usually causes the laser to mode hop a few times in steps of 5–8 GHz (roughly equal to the extended-cavity mode spacing), before making a much larger mode hop corresponding to the 50 GHz free spectral range of the solitary laser diode cavity. The resulting ‘‘holes’’ in the tuning curve can be shifted away from a region of interest by adjusting the laser temperature. The frequency of the solitary SDL-5401 laser diode tunes with temperature at about 35 GHz/K.