We have demonstrated operation of a cleaved‐coupled‐cavity (C3) diode laser of PbS1−xSexin the 4–5‐&mgr;m infrared spectral region. It was possible to obtain improved laser mode control by adjusting the modulator section current. Reproducible single mode operation with 1.5 mW of cw output power at 175 mA of laser current (power efficiency of 3.5%) was observed. A single mode tuning range of 2.16 cm−1was obtained at a lower power value. Laser frequency tuning rates were found to be significantly reduced by use of modulator current tuning as opposed to laser current tuning. The observed results suggest that the C3Pb‐salt laser may provide a much greater degree of mode control than has been possible with single‐cavity lasers.