Optimal waveguide structure for low-threshold InGaN/GaN-based photonic-crystal surface-emitting lasers
Wen-Hsuan Hsieh,
Duan-Hsin Huang,
Tien-Chiu Chen,
Po-Yang Chang,
Tien-Chang Lu,
Chia-Yen Huang
Affiliations
Wen-Hsuan Hsieh
Department of Photonics and Institute of Electro-Optical Engineering, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
Duan-Hsin Huang
Department of Photonics and Institute of Electro-Optical Engineering, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
Tien-Chiu Chen
Department of Photonics and Institute of Electro-Optical Engineering, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
Po-Yang Chang
Department of Photonics and Institute of Electro-Optical Engineering, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
Tien-Chang Lu
Department of Photonics and Institute of Electro-Optical Engineering, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
Chia-Yen Huang
Department of Photonics and Institute of Electro-Optical Engineering, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
We analyzed the optimal waveguide structure of two types of InGaN-based photonic crystal surface-emitting lasers (PCSELs) to suppress the coupling with leaky modes via mode simulations. To minimize the threshold material gain (gth), we calculated the confinement factor and quality factor of PCSELs with varying waveguide layer thicknesses in the separate confinement heterostructure (SCH) layer. The optical mode intensity profile revealed the coupling between the fundamental mode of SCH and parasitic leaky modes in the cladding layer or substrate as the primary root cause of the low-quality factor and high threshold gain of PCSELs. The asymmetric nature of the SCH structure yielded the optimal waveguide structure to be dependent on the position of the air holes. With a proper waveguide thickness and air hole depth, the optimized threshold modal gain of PCSELs with the n-side air holes can be less than 30 cm−1.
