650nm red VCSELs with improved temperature performance

In this paper, we report on design optimization, design, and fabrication of single-junction red VCSELs emitting at the wavelength of ~650nm with improved power and temperature performance. This has been achieved through redesigning the VCSEL epitaxial structure by optimizing the number of top and bottom mirror pairs to reduce the optical losses, optimizing p-DBRs’ doping concentration levels, changing the oxide layer thickness and position relative to the active region, and adjusting the wavelength detuning between peak wavelength of the gain medium and the Fabry-Perot dip wavelength. Moreover, several changes have been implemented to improve the carrier confinement in the active region to improve the performance of these devices at higher temperatures. These include optimizing the net strain across the active region, modifying the electron blocking layers, and also optimizing the number and thickness of InGaP-based multiple quantum wells. The CW characterization results indicate a record-high output optical power of 4.25mW at room temperature for a 14μm VCSEL. The temperature-variable L-I-V characterization results indicate a maximum lasing temperature of 50°C for the 14μm VCSEL, while the 5μm device has shown to be lasing up to 80°C. All devices have shown to be highly multi-mode spectrally, but with different far-field beam profiles. Moreover, the results indicate that the output light from these devices are strongly polarized in the <011> direction. Overall, the results depict a promising roadmap into developing high brightness red VCSELs which have superior performance over a broad temperature range