The spectral characteristics of rooftop reflector (RTR) laser diode and serpentine shaped laser diode (SSLD) are presented. Lasers are fabricated using two step Cl-2-based reactive ion beam etching (RIBE). It is found that spectra of RTR laser and SSLD are very different from those of Fabry-Perot cavity lasers. Also Y-branch optical waveguide with total internal reflector (TIR) mirror was fabricated to measure backward reflection from the TIR mirror. The results suggest that the spectra of lasers with TIR mirrors have a strong longitudinal mode selectivity due to the scattering and reflection at TIR mirror.