The structure of DAL-DC-PBH laser diode (LD) is given in Fig. 1. The output FP mode spacing of the DAL structure depends on the difference between N1 and N2, which are the effective refractive Indices of the first and second active layers grown in the 1 LPE step, respectively1,2: , where λ0 is the lasing wavelength and L is the cavity length. If we choose the same material (λ0 = 1.52 μm) for the two active layers, N1 ≅ N2: thus we have |N1 – N2| « N', that is, A (where only one active layer exists, and it has N' as its effective refractive index). The spectral gain profiles for both active stripes are the same, the side modes of the DAL LD hardly have enough gain to be stimulated because they are far from the center mode which may receive enough gain.
© 1987 Optical Society of AmericaPDF Article