The wavelength tunable range was widened in a three electric section strained multi quantum well distributed feedback laser by using the gain lever effect. When the fixed bias currents are injected into the two sections, another section is the control section (its length is 0.33 of the all cavity length). The lasing wavelength becomes longer when the current of the control section is increased. The maximum continuous tuning range (without mode hopping) is 0.82 nm at 1.538 μm. It still can be continuously tuned after mode hopping.