Photolithography allows high-Q AlN microresonators for near octave-spanning frequency comb and harmonic generation
Jia Liu, Hai‐Zhong Weng, Adnan Ali Afridi, Jing Li, Jiangnan Dai, Xiang Ma, Hanling Long, Yi Zhang, Qiaoyin Lu, John F. Donegan, Weihua Guo
Abstract
Single-crystal aluminum nitride (AlN) possessing both strong Pockels and Kerr nonlinear optical effects as well as a very large band gap is a fascinating optical platform for integrated nonlinear optics. In this work, fully etched AlN-on-sapphire microresonators with a high-Q of 2.1 × 10 6 for the TE 00 mode are firstly demonstrated with the standard photolithography technique. A near octave-spanning Kerr frequency comb ranging from 1100 to 2150 nm is generated at an on-chip power of 406 mW for the TM 00 mode. Due to the high confinement, the TE 10 mode also excites a Kerr comb from 1270 to 1850nm at 316 mW. In addition, frequency conversion to visible light is observed during the frequency comb generation. Our work will lead to a large-scale, low-cost, integrated nonlinear platform based on AlN.