Fabrication and Characterization of Low-Threshold Single Fundamental Mode VCSELs With Dielectric DBR Mirror

The SiO
₂
/SiN
_x
dielectric film stacks deposited by inductively coupled plasma chemical vapor deposition (ICP-CVD) are employed on the top of the oxide-confined vertical-cavity surface-emitting lasers (VCSELs). The reflecting mirror characteristics of the dielectric films are measured with varying numbers of pairs from 4 to 12. The prepared devices have low threshold current of 0.3 mA, single-mode peak power of 1.4 mW at room temperature. The thermal resistance of the device depending on ambient temperature is estimated according to the relationship of wavelength shift and dissipated power, allowing us to extract the actual temperature in active region and the temperature dependence of the output characteristics of the VCSEL. The beam property of the device is characterized by the far field pattern (FFP). Depending on the drive current, the average divergence angles of the output beam estimated from the full-width-half-maximum (FWHM) of the FFP varies between 20.4° and 21.2°. Furthermore, polarization-controlled single mode emission is achieved by introducing a built-in grating into the VCSEL with orthogonal polarization suppression ratio (OPSR) around 19 dB.