We have theoretically investigated the band structure engineering and optical gain spectra of dilute-bismide and bismide-free respectively in GaAsBi/GaAsP and GaAs/GaAsP laser structures. Subsequently, a type-I strain-compensated GaAs0.97Bi0.03/GaAs0.7P0.3 quantum well heterostructure which was optimized in terms of compositions and thicknesses has been studied by solving Schrodinger equation. We found that the incorporation of a small fraction of bismuth in the laser active region enhances significantly the optical properties such as the optical gain, which leads to a peak gain value of nearly 1000 cm-1 corresponding to a usual injection carrier concentration of 1.5 × 1012 cm-2. A modal gain value equal to 80 cm-1 can be reached and radiative current density less than 50 A/cm2 is expected. These latter results demonstrate that the dilute-bismide GaAsP/GaAsBi/GaAsP laser heterostructure arouses a great interest due to their high-power near-infrared light emitting diodes (LED) and laser diodes (LD) operating at room temperature (RT).