Surface-emitting distributed feedback laser based on high-order gratings.

This paper reports a surface-emitting (SE) distributed feedback laser based on high-order surface gratings. The proposed device not only retains the advantages of edge-emitting lasers such as excellent single-mode property, high internal quantum efficiency, and high output power but also obtains other appealing characteristics, such as easy realization of the hybrid integration, the simple fabrication process, etc. The SE distributed feedback laser is analyzed and optimized for better performances using an improved traveling wave model.

Inverse design and demonstration of an ultracompact broadband dual-mode 3 dB power splitter.

An ultracompact broadband dual-mode 3 dB power splitter using inverse design method for highly integrated on-chip mode (de) multiplexing system is proposed and experimentally demonstrated. A dual-mode convertor based on subwavelength axisymmetric three-branch waveguide is utilized to convert TE0 and TE1 to three intermediate fundamental modes. The axisymmetric topology constraint of the nanostructures enables the optimized device to achieve a strict 50:50 splitting ratio over a broad wavelength range from 1.52 to 1.60 µm. The fabricated device occupied a compact footprint of only 2.88 µm × 2.88 µm. The measured average excess losses and crosstalks for both modes were respectively less than 1.5 dB and -20 dB from 1.52 to 1.58 µm for both TE0 and TE1, which are consistent with the numerical simulations.