GHz ultrahigh-order harmonic laser output based on nonlinear multimode interference
Abstract
Optical frequency combs (OFCs) with GHz repetition rates are being widely used. They are applied in high-speed fiber communications, microwave photonics, and precision spectroscopy. However, achieving stable ultrahigh-order harmonic generation at low pump power remains a major challenge in mode-locked fiber lasers. A harmonic mode-locking (HML) fiber laser based on nonlinear multimode interference is proposed and demonstrated. Theoretical analysis indicates that splicing a graded-index multimode fiber with a highly nonlinear fiber (HNLF) not only enhances mode purity through multimode interference filtering but also substantially reduces the soliton area due to the large nonlinear coefficient. Consequently, the threshold for harmonic generation is being reduced. Experimental results confirm a stable 571st harmonic output. A 5 m HNLF under 1 W pump power, corresponding to a repetition rate of 7.006 GHz, with excellent frequency stability and a signal-to-noise ratio of 40 dB. This HML structure is supported by theoretical and experimental investigations. It offers a low-cost and scalable approach to the development of stable OFCs with GHz repetition rates.
Article Details
Journal Info
Applied Physics Letters
American Institute of Physics
Authors (9)
Chao Lv
Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, College of Chemistry and Materials Science
Bin Yin
Guofeng Sang
Institute of Marine Technology, Faculty of Information Science and Engineering, Ocean University of China 1 , 266100 Qingdao,
Hongwei Zhang
Key Laboratory of Development and Application of Rural Renewable Energy
Haisu Li
YanZhi Lv
State Key Laboratory on Tunable Laser Technology, School of Electronic and Information Engineering, Harbin Institute of Technology 4 , Shenzhen 518055,
Yiming Wang
Li Pei
Key Lab of All optical Network and Advanced Telecommunication Network of EMC, Institute of Lightwave Technology Beijing Jiaotong University 3 , Beijing 100044,
Songhua Wu