HighLy Collimated Gaussian-Beam Emission of VCSEL in the Visible Red Spectral Range for Sensing and Fiber Applications

Vertical-cavity surface-emitting lasers (VCSELs) have emerged as promising candidates for a variety of applications, including sensing, printing, and data transfer, due to their exceptional characteristics such as low power consumption, low threshold current, and long operational life. The potential for arranging them in arrays is also noteworthy. Notably, VCSELs are particularly attractive in the red spectral range of 650–670 nm, making them well-suited for biomedical applications [2], [3]. However, their implementation is occasionally hindered by the emission of light at an angle of divergence of approximately 10° for single fundamental-mode operation [4]. For increased output-power operation, higher-order transverse modes are emitted, further increasing the divergence and deviating from Gaussian symmetry, thereby limiting the fiber coupling efficiency. Consequently, various techniques have been investigated to decrease the angle of divergence and the number of emitted transverse higher-order modes for VCSELs emitting at different wavelengths [5].