PERFORMANCES AND RELIABILITY OF 850NM VCSELS WITH

The 850nm VCSELs with various wavelength offsets in gain peak and FabyPerot dip were designed andfabricated. The VCSEL with IO nm offset has the fhreshold current with less temperature sensitivity and the best reliability. Verticakavity surface-emitting lasers (VCSELs) are attractive light sources for many optoelectronic applications due to their intrinsic properties of surface emission, circular output beam, lowcurrent operation, etc (I). The VCSEL's performances are sensitive to the mismatch in the position of the Fabry-Pent (FP) cavity resonant peak and the gain peak (GP) (2). Because both the 8 and the FP resonance will shift to longer wavelength when the device temperature increases during the device operation with the GP shifting faster than the FP resonance (3). For the optimum device performances, therefore the GP is typically designed to offset at a shorter wavelength side of the FP dip. To allow better alignment of these two peaks for wide temperature range of continuous-wave (cw) operation. In this paper, we report the performance comparison of GaAs VCSELs with various peak wavelength offsets between GP and FP dip and obtain optimum offset condition for the stable and reliable operation. Fig. I shows the temperature dependence of the threshold current (Im) for VCSEL A, B and C and it suggests that the VCSEL B has Ith with less temperature sensitivity in wide range at 25-700C. Fig. 2 shows the LI-V curve over temperature of the B. The VCSEL exhibits decrease in the slop efficiency (SE) with temperature. Finally we performed high temperature operating lifetest on these VCSELs (20 units for each VCSEL), at the operating condition of 18mA and 90 OC (standard module bum in condition). Fig. 3 suggests VCSEL B has the smallest increasing rate with better reliability operation. In conclusion, The VCSEL B with wavelength offset of IO nm has the lowest threshold current with less temperature sensitivity under continuous-wave operation and has the better operational reliability.