Analysis of Mode Characteristics in Semiconductor Lasers With Asymmetric Coupled Cavities Based on Quasi Parity-Time

Abstract

This study presents a novel asymmetrically coupled cavity (ACC) semiconductor laser structure designed to achieve stable single-mode operation in wider ridge waveguides, enhancing output power. The proposed structure consists of a gain ridge waveguide and an electrically insulated lossy ridge waveguide, enabling flexible control of transverse modes through the coupling effect between the fundamental mode of the lossy waveguide and the first-order mode of the gain waveguide. By optimizing key parameters—ridge waveguide width, spacing, and etching depth—the ACC forms a new optical mode distribution that suppresses higher-order modes through significant optical loss in the lossy section while the fundamental mode remains confined to the gain waveguide. The newly defined variables—the optical field proportion factor and the modal regulation factor—quantify the loss characteristics of higher-order modes. Combined with the influence of propagation length on the control of ACC coupling modes, the optimal range for structural parameters in achieving single-mode operation can be determinate.

Keywords

• Semiconductor laser
• mode selection
• modal loss
• coupled asymmetric ridge waveguide