Author Affiliations
Abstract
National Key Laboratory of Microwave Photonics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
An approach for frequency division of an optical pulse train (OPT) based on an optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. When the OPT is injected into the OEO, a microwave signal with a frequency equaling fractional multiples of the repetition rate of the OPT is generated. This signal is then fed back to the OEO, maintaining its oscillation, while simultaneously serving as the control signal of a Mach–Zehnder modulator (MZM) in the OEO. The MZM acts as an optical switch, permitting specific pulses to pass through while blocking others. As a result, the repetition rate of the OPT is manipulated. A proof-of-concept experiment is carried out. Frequency division factors of 2 and 3 are successfully achieved. The phase noises of the OPT before and after the frequency division are investigated. Compared to previously reported systems, no external microwave source and sophisticated synchronization structure are needed.
frequency division optoelectronic oscillator mode-locked laser microwave photonics Chinese Optics Letters
2024, 22(4): 043902
1 重庆大学光电技术及系统教育部重点实验室，重庆 400044
2 华中科技大学光学与电子信息学院，湖北 武汉 430074
3 南方科技大学电子与电气工程系，广东 深圳 518055
随着超快激光应用需求的不断增长，激光控制技术正面临越来越多的挑战，超短脉冲操控研究亟待取得进一步的突破与发展。在激光器谐振腔增益、色散、损耗、非线性等效应共同作用下，多脉冲展现出比单脉冲更为丰富的动力学现象。研究表明其内部脉冲间距、相对相位、脉冲个数等参量具有高度可控性，为提升多脉冲的操控维度提供了新思路。本文从超快激光多脉冲的操控机理出发，介绍了多脉冲动力学、实时观测技术及激光器控制方法，重点综述了基于增益调制、偏振控制、色散调控、光机械效应等多脉冲操控方案，分析了各方案的性能，并展望了多脉冲操控技术的发展前景。
超快激光 超短脉冲 多脉冲束缚态 脉冲操控 锁模激光器 激光与光电子学进展
2024, 61(3): 0314002
Author Affiliations
Abstract
1 Institute of Microscale Optoelectronics, College of Electronics and Information Engineering, Shenzhen University, Shenzhen 518060, China
2 Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology, Center for Advanced Material Diagnostic Technology, College of Engineering Physics, Shenzhen Technology University, Shenzhen 518118, China
We demonstrate the generation of a unique regime of multiple solitons in a Tm-doped ultrafast fiber laser at ∼1938.72 nm. The temporal pulse-to-pulse separation among the multiple solitons, 10 in a single-pulse bunch, increases from 0.89 ns to 1.85 ns per round trip. In addition, with the increasing pump power, the number of bunched solitons increases from 3 up to 24 linearly, while the average time separation in the soliton bunch varies irregularly between ∼0.80 and ∼1.52 ns. These results contribute to a more profound comprehension of nonlinear pulse dynamics in ultrafast fiber lasers.
mode-locked fiber laser multiple solitons pump hysteresis pulse-to-pulse interval Chinese Optics Letters
2024, 22(3): 031405
Author Affiliations
Abstract
Key Laboratory of Intelligent Optical Sensing and Manipulation of the Ministry of Education & National Laboratory of Solid State Microstructures & College of Engineering and Applied Sciences & Institute of Optical Communication Engineering & Nanjing University-Tongding Joint Lab for Large-Scale Photonic Integrated Circuits, Nanjing University, Nanjing 210023, China
We propose and experimentally demonstrate the programmable photonic radio frequency (RF) filters based on an integrated Fabry–Pérot laser with a saturable absorber (FP-SA). Owing to the high output power and the relative flatness spectrum of the FP-SA laser, only a waveshaper and an erbium-doped fiber amplifier (EDFA) were needed, which can greatly reduce the complexity of the system. The sinc filter employed 87 taps, representing a record-high tap number and resulting in a 3-dB bandwidth of 0.27 GHz and a quality factor of 148. Furthermore, Gaussian apodization enabled the out-of-band rejection of the filter to reach 34 dB and the center frequency to be finely tuned over a wide range, spanning from 4 to 14 GHz. These results indicate that the proposed scheme could provide a promising guideline for the photonic RF filters that demand both high reconfigurability and greatly reduced size and complexity.
microwave filters microwave photonics passively mode-locked laser Chinese Optics Letters
2024, 22(2): 023901
上海交通大学电子信息与电气工程学院区域光纤通信网与新型光通信系统国家重点实验室，上海 200240
飞秒激光在学术领域和工业领域都具有极高的应用价值，对飞秒激光进行准确快速的表征与精确控制对其各种应用至关重要。飞秒脉冲的传统表征方法依赖非线性效应且光路结构复杂，而飞秒脉冲的控制则大多采用开环手动调试，无法实现稳定的最优调控，极大地限制了飞秒激光的应用。近年来，智能技术的出现给飞秒激光研究提供了新范式，结合智能技术，低能量高重复频率飞秒脉冲序列的单帧全域测量与飞秒脉冲的按需智能调控有望成为现实。
锁模激光器 飞秒脉冲智能表征 飞秒脉冲智能调控 激光与光电子学进展
2024, 61(1): 0114006
1 上海大学特种光纤与光接入网重点实验室，上海先进通信与数据科学研究院，特种光纤与先进通信国际合作联合实验室，上海 200444
2 中国计量科学研究院，北京 100029
3 华中科技大学光学与电子信息学院下一代互联网接入系统国家工程实验室，湖北 武汉 430074
4 东莞理工学院电信工程与智能化学院，广东 东莞 523808
5 华东师范大学精密光谱科学与技术国家重点实验室，上海 200062
6 浙江省引力波精密测量重点实验室国科大杭州高等研究院，浙江 杭州 310024
利用45°倾斜光纤光栅（45°-TFG）作为光纤型起偏器，搭建了一台高可靠性高稳定性的掺铒锁模光纤激光器，并以此为基础实现了重复频率和载波包络偏移频率的精确锁定。当泵浦功率为228 mW时，基于45°-TFG的锁模激光振荡器可实现3 dB光谱带宽为60.4 nm、脉冲宽度为68 fs的超短脉冲输出，在12 h内功率的均方根稳定性达到0.033%，且在较大的泵浦范围内均能维持较好的展宽锁模状态。经过自主搭建的非线性脉冲放大、超连续谱产生以及自参考拍频干涉光路，获得了信噪比为32 dB的信号。最后通过搭建基于锁相环的主动反馈控制电路，将和信号溯源至一台GPS时频系统，最终测得和信号归一化后在1 s门时间内频率稳定度为2.38×10-12和6.41×10-16。这是首次实现基于45°-TFG的光纤激光频率梳，表明了基于45°-TFG的锁模光纤激光器在实际应用中的潜力。
锁模光纤激光器 光纤光栅 非线性偏振旋转 光纤激光频率梳 激光与光电子学进展
2024, 61(1): 0106005
1 清华大学精密仪器系精密测试技术与仪器国家重点实验室，北京 100084
2 北京邮电大学电子工程学院信息光子学与光通信全国重点实验室，北京 100876
在光纤锁模激光器中，模式相位锁定产生周期短脉冲的过程称为锁模过程，产生的脉冲在广义上被称为“光耗散孤子”。光纤锁模激光器从传统的单模光纤锁模激光器发展到了多模光纤锁模激光器，锁模机理从一维（1D）时域耗散孤子锁模发展到了（3+1）维时空耗散孤子锁模。通过深入理解耗散孤子的产生机理，有望进一步推动光纤锁模激光器在科学和应用领域的发展，为更多领域带来更多创新和可能性。首先介绍单模光纤锁模激光器中的一维时域耗散孤子锁模，探讨不同色散区域中时域耗散孤子的产生机理；随后介绍多模光纤锁模激光器中时空耗散孤子的最新研究成果，讨论模间色散的补偿方法，揭示其丰富的时空锁模机理和潜在的应用场景；最后对光纤锁模激光器的发展前景进行展望。
1 中国科学院合肥物质科学研究院安徽光学精密机械研究所，光子器件与材料安徽省重点实验室，安徽 合肥 230031
2 先进激光技术安徽省实验室，安徽 合肥 230037
3 国防科技大学脉冲功率激光技术国家重点实验室，安徽 合肥 230037
4 中国科学技术大学环境科学与光电技术学院，安徽 合肥 230026
本文报道了一种可满足室外应用的具有重复频率锁定功能的皮秒脉冲光纤激光器。通过选用Figure-9光纤激光器结构，并通过优化腔结构来调控非线性，确保了激光器的快速锁模自启动功能；采用低导热材料绝热封装创建“恒温”微环境，松弛了室外环境下锁定重复频率对PZT频率调谐执行器件调谐量的要求。以此为基础，设计并研制了质量仅为3 kg的10 MHz、20 ps锁模光纤激光器样机。在室温、极端温度（-40 ℃或50 ℃）和振动（加速度为1.5g）环境下，该激光器样机都能保持快速锁模自启动和重复频率锁定功能；在室外环境下，该激光器样机的重复频率锁定功能可抵御夏季高温环境下的10 ℃温度波动。
激光器 锁模激光 皮秒脉冲 重复频率锁定 环境温度
