-
In this paper, a novel scheme is proposed and experimentally demonstrated. It is based on a directly modulated laser (DML) and all-optical mode-locking for generating tunable microwave frequency combs (MFCs). Theoretical analysis reveals that harmonic or rational harmonic mode-locking can be achieved by adjusting the parameters of the fiber ring cavity, which enables the generation of MFCs with adjustable comb spacing. Based on this, experimental verification shows that the DML can be driven to exhibit various typical dynamical states under sinusoidal modulation with different frequencies and amplitudes. These states serve as seeding signals that subsequently undergo all-optical mode-locking within the ring laser cavity, resulting in the generation of MFCs. The bandwidths of the MFCs are 13, 15, 19.5, 19.8, and 22 GHz, respectively, all of which satisfy the ±5 dB flatness criterion. A continuously tunable comb-spacing range of 200 MHz to 3 GHz is attained through the effective combination of the DML and all-optical mode-locking. The single-sideband (SSB) phase noise of the first comb line remains below –100 dBc/Hz at a 10 kHz offset. Theoretical analysis and experimental results demonstrate that the modulated signals of the proposed scheme support flexible parameter tuning over a wide range. Furthermore, the generated MFCs have remarkable advantages in flatness, bandwidth, and tunability.
-
Keywords:
- directly modulated laser /
- dynamic states /
- all-optical mode-locking /
- microwave frequency comb
-
图 1 基于DML与全光锁模产生可调谐MFC的结构图(RF, 射频信号源; DML, 直调激光器; VOA, 可变光衰减器; Cir, 光环行器; PC, 偏振控制器; SOA, 半导体光放大器; ODL, 光延迟线; TOF, 可调光滤波器; EDFA, 掺铒光纤放大器; OC, 光耦合器; ISO, 光隔离器)
Figure 1. Schematic of tunable MFCs generated by DML and all-optical mode-locking. RF, radio frequency source; DML, directly modulated laser; VOA, variable optical attenuator; Cir, optical circulator; PC, polarization controller; SOA, semiconductor optical amplifier; ODL, optical delay line; TOF, tunable optical filter; EDFA, erbium-doped fiber amplifier; OC, optical coupler; ISO, optical isolator.
图 2 全光锁模的实验验证 (a) 测量FRL的自由光谱范围(FSR); (b) 谐波锁模; (c) 二阶有理数谐波锁模; (d) 三阶有理数谐波锁模
Figure 2. Experimental verification of all-optical mode-locking: (a) The measured free spectral range (FSR) of the FRL; (b) Harmonic mode-locking; (c) second-order rational harmonic mode-locking; (d) third-order rational harmonic mode-locking.
图 3 不同动力学态作为种子信号产生MFC (a) SS; (b) CPSSH; (c) CPS2SH; (d) PP2SH; (e) PPSH(第1列为DML输出的时间序列, 第2列为DML输出的频谱, 第3列为系统输出的时间序列, 第4列为系统输出的频谱)
Figure 3. The MFCs generated by using different dynamical states as the seed signals: (a) SS; (b) CPSSH; (c) CPS2SH; (d) PP2SH; (e) PPSH (Column 1 represents the time series at the DML output; Column 2 represents corresponding frequency spectrum at the DML output; Column 3 represents the time series at the system output; Column 4 represents corresponding frequency spectrum at the system output).
图 4 不同RF信号产生的MFC的频谱 (a) 200 MHz, 插图为0—5 GHz放大图; (b) 300 MHz, 插图为0—7 GHz放大图; (c) 400 MHz, 插图为0—10 GHz放大图; (d) 500 MHz; (e) 1 GHz; (f) 1.5 GHz; (g) 2 GHz; (h) 2.5 GHz; (i) 3 GHz
Figure 4. Spectra of microwave frequency combs generated by different RF signals: (a) 200 MHz, the illustration is an enlarged view from 0 to 5 GHz; (b) 300 MHz, the illustration is an enlarged view from 0 to 7 GHz; (c) 400 MHz, the illustration is an enlarged view from 0 to 10 GHz; (d) 500 MHz; (e) 1 GHz; (f) 1.5 GHz; (g) 2 GHz; (h) 2.5 GHz; (i) 3 GHz.
图 5 MFC的相位噪声与稳定性 (a) 不同动力学态产生的MFC的相位噪声; (b)动力学态为SS与PPSH时, 产生的MFC的一阶梳线的稳定性; (c)种子信号为PPSH时, 不同梳间距的MFC在10 kHz偏移处的一阶梳线相位噪声
Figure 5. The phase noise diagram of MFCs: (a) Phase noise of MFCs generated under different dynamical states; (b) the stability of the first comb line of the MFCs when the dynamical states are SS and PPSH; (c) phase noise of the first comb line at a 10 kHz offset for MFCs with various comb spacings when the seed signal is PPSH.
-
[1] Xu Z W, Shu X W 2019 J. Lightwave Technol. 37 3503
Google Scholar
[2] Shin J, Ryu Y, Miri M A, Shim S B, Choi H, Alù A, Suh J, Cha J 2022 Nano Lett. 22 5459
Google Scholar
[3] Zhang L H, Liu Z K, Liu B, Zhang Z Y, Guo G C, Ding D S, Shi B S 2022 Phys. Rev. Appl. 18 014033
Google Scholar
[4] 刘琪华, 梅佳雪, 王金栋, 张福民, 曲兴华 2024 物理学报 73 044204
Google Scholar
Liu Q H, Mei J X, Wang J D, Zhang F M, Qu X H 2024 Acta Phys. Sin. 73 044204
Google Scholar
[5] Picqué N, Hänsch T W 2019 Nat. Photonics 13 146
Google Scholar
[6] Wang S P, Chen Z, Li T F 2021 Chin. Phys. B 30 048501
Google Scholar
[7] Wu S S, Liu Y L, Liu Q C, Wang S P, Chen Z, Li T F 2022 Phys. Rev. Lett. 128 153901
Google Scholar
[8] Wu D X, Xue X X, Li S Y, Zheng X P, Xiao X D, Zha Y, Zhou B K 2017 Opt. Express 25 14516
Google Scholar
[9] Gao S, Gao Y, He S 2010 Electron. Lett. 46 236
Google Scholar
[10] 麻艳娜, 黄添添, 王文睿, 宋开臣 2018 物理学报 67 238401
Google Scholar
Ma Y N, Huang T T, Wang W R, Song K C 2018 Acta Phys. Sin. 67 238401
Google Scholar
[11] Yang B, Zhao H Y, Cao Z Z, Yang S, Zhai Y R, Ou J, Chi H 2020 Opt. Express 28 33220
Google Scholar
[12] Wang Z Y, Wu R H, Li B, Guo J P, Liu H Z 2023 Opt. Laser Technol. 162 109253
Google Scholar
[13] Tang H Y, Kong Z X, Li F P, Chen X Y, Li M, Zhu N H, Li W 2024 J. Lightwave Technol. 42 5522
Google Scholar
[14] Chan S C, Xia G Q, Liu J M 2007 Opt. Lett. 32 1917
Google Scholar
[15] 周沛, 张仁恒, 朱尖, 李念强 2022 物理学报 71 214204
Google Scholar
Zhou P, Zhang R H, Zhu J, Li N Q 2022 Acta Phys. Sin. 71 214204
Google Scholar
[16] Juan Y S, Lin F Y 2009 Opt. Lett. 34 1636
Google Scholar
[17] Zhuang J P, Li X Z, Li S S, Chan S C 2016 Opt. Lett. 41 5764
Google Scholar
[18] Li Y N, Fan L, Xia G Q, Wu Z M 2017 IEEE Photonics J. 9 5502607
[19] Zhao W, Mao Y F, Li Y B, Chen G C, Lu D, Kan Q, Zhao L J 2020 IEEE Photonics Technol. Lett. 32 1407
Google Scholar
[20] Gao T C, Zhang Y L, Li J C, Li S H, Zhang Z Y, Zhang S J, Liu Y 2024 Opt. Laser Technol. 170 110295
Google Scholar
[21] Ahmed M, El-Lafi A 2008 Opt. Laser Technol. 40 809
Google Scholar
[22] Das P, Kaechele W, Theimer J P, Pirich A R 1997 Photonic Process. Technol. Appl. 3075 21
[23] Wu C, Dutta N K 2000 IEEE J. Quantum Electron. 36 145
Google Scholar
[24] Zi Y J, Jiang Y, Ma C, Bai G F, Jia Z R, Wu T W, Huang F Q 2015 IEEE Photonics J. 7 1501309
[25] Hemery E, Chusseau L, Lourtioz J M 1990 IEEE J Quantum Electron. 26 633
Google Scholar
DownLoad:
Metrics
- Abstract views: 37
- PDF Downloads: 0
- Cited By: 0
