An integrated laser having increased rate of the spontaneous emission is proposed a apply this device as a light source giving weaken optical coherency. This device consists of two sections, one is a Light-Emitting-Diode (LED)-section and another is a Laser-section. The spontaneous emission is generated and amplified in the LED-section, then injected into the Laser-section. Power of the incoherent light in the Laser-section becomes more than ten times of that in the conventional single section laser with the help of the light injection. Wider half width of the output spectrum more than 1.5 nm is obtained at injection current level of I/Ith=1.5 in GaAs DH structure. Mechanism and fundamental properties of this device are analyzed with the help of both classical Maxwell's equation and quantum mechanics.