Surface relief VCSELs at 670nm with integrated polymer microlens for highly collimated fundamental-mode emission

• Lena Engel, Farnaz Khamseh, Michael Zimmer, Michael Jetter, and Peter Michler
• received 03/21/2024; accepted 04/24/2024; posted 04/24/2024; Doc. ID 524493
• Abstract: We demonstrate the integration of a wet-chemically etched surface relief on a VCSEL emitting in the red spectral range for higher-order mode suppression. With this relief, fundamental-mode emission is achieved over the entire power range from threshold beyond thermal rollover. For collimation of the emitted beam, we implement polymer microlenses fabricated on-chip by thermal reflow technique. We reduce the angle of divergence for all injected currents to a maximum of 2°. By measuringhigh-resolution spectra, we show that Gaussian beam profiles correspond to pure fundamental-mode emission which is preserved after implementation of the polymer microlens onto the etched relief, proving the compatibility of the two processes.