Elimination of catastrophic optical mirror damage in high-power laser diodes using multi-section waveguides

Abstract

One of the solid constraints of high-power laser diodes (LDs) has been catas-trophic optical mirror damage (COMD), restricting the operating power level and lifetime of commercial high-power laser diodes (LDs). The output facet of LD reaches a critical temperature leading to COMD, a permanent device fail-ure. Here, we fabricate multi-section LDs by tailoring the waveguide structure along the cavity that distances the output facet from the heat-generating lasing region. This method splits the LD waveguide into electrically isolated laser and window sections along the cavity. The laser section is operated at a high current to achieve high output power, and the window is biased at a low current with minor heat generation. This technique limits the thermal impact of the laser sec-tion on the facet, and the window section enables lossless transport of the laser to the output facet. First, we compared standard broad area laser diode with multi-section waveguide LDs up to the maximum achievable power. While tradi-tional single-section LDs show COMD failures, the multi-section waveguide LDs are COMD-free. Next, we implemented our method on narrow waveguide laser diodes and array lasers with different widths and confirmed the cooling effect on the fabricated LD facet. Therefore, our novel technique and results show that the multi-section waveguide method provides substantial reliability improvement for various LD types, such as broad-area, narrow waveguide, and array/bars.