InAsSb/InAsSbP double heterostructure diode lasers for the spectral range of 3.3 μm grown by liquid phase epitaxy have been investigated. Emission spectra, far–field patterns and wavelength tuning versus current have been studied in the wide current range from threshold value Ith up to 3Ith at the temperature of liquid nitrogen. Controlled by current, wavelength tuning in single–mode lasing has been obtained both towards the shorter wavelengths (up to 4.56 cm−1) and towards the longer wavelengths (up to 0.9 cm−1) at the temperature T = 77 K. Comparison of the emission properties of the lasers, driven by different types of current (short pulse current, sawtooth pulse current and in quasi–continuous–wave (CW) regime) showed the same quantum–mechanical nature of current tuning. The theoretical model of this nonlinear optical phenomenon is proposed. The estimated times of current tuning defined mainly by the photon lifetime in the cavity are ca. 10−9 to 10−12 s.