An external‐cavity semiconductor laser employing a birefringent electro‐optic modulator for wavelength tuning is described. Wide‐band tuning over 70 A˚ in a single frequency to residual diode modes and narrow‐band tuning over 0.42 A˚ to many longitudinal modes of the external cavity is demonstrated using different modulator configurations. Threshold current and quantum efficiency are nearly as good as that of the solitary laser diode.