A new asymmetric dual quantum well laser diode with a segmented contact is proposed. With inhomogeneous current injection, the lasing wavelength can be changed quasi‐continuously over 22 nm, which is much wider than any tuning range previously reported. To achieve such wide‐range tuning, it is found to be essential that the length of the cavity and each segment (and the mirror reflectivity) of the laser diode should be within an optimized range. In the asymmetric dual quantum well laser diode structure used in the present experiment, in particular, the cavity length should be such that light of a shorter wavelength lases under homogeneous excitation.