[TuP3D] D. Photonic devices and related technologies

[TuP3D-08] Improved Lasing Characteristics in Circular Defect in 2D Photonic Crystal (CirD) Laser by Employing of Sub-Cavity

〇Yuto Nakai¹, Yuto Kudo¹, Kazuki Sato¹, Masato Morifuji¹, Hirotake Kajii¹, Akihiko Maruta¹, Tetsuya Yagi¹, Nobuhiko Kikuchi¹, Masahiko Kondow¹ (1. The Univ. of Osaka (Japan))

This study reports on the experimental improvement of circular defect (CirD) photonic crystal lasers designed for low-power, on-chip WDM optical communications. By introducing an asymmetrical structure with an L2 sub-cavity, we successfully improved output directionality and intensity. Considering the 10 dB coupling loss between the waveguide output facet and the lensed fiber, the targeted experimental output power from the waveguide facet was tentatively 100 nW. Furthermore, the output power can be increased by removing InAs QDs in the outside of the CirD cavity. Three-dimensional FDTD simulations showed that matching the resonance frequencies of the CirD cavity, sub-cavity, and waveguide achieves strong mode coupling, resulting in increased output intensity in the designed direction. The structure was fabricated on a GaAs/AlGaAs epitaxial wafer by ICP-RIE, and the AlGaAs lower cladding layer was partly oxidized and converted into AlOx to remain the AlGaAs funnel. Under continuous wave optical pumping at room temperature, the fabricated CirD laser with a sub-cavity succeeded in outputting more than the targeted value. Additionally, the structure achieved a side-mode suppression ratio (SMSR) of approximately 42 dB, an improvement of 5 dB compared to the conventional structure. This indicates that output power and SMSR can be improved by employing a sub-cavity.