【摘要】 窄线宽激光器是现代光电子系统的核心器件。随着现代信息系统向高速率、高精度、大规模方向发展，迫切需要兼具超窄线宽、宽调谐范围和快速调谐能力的新型芯片化光源。硅基集成外腔激光器同时结合了半导体激光器技术和硅基光子集成技术的优势，成为近年来集成光子学领域和激光器领域的重要突破。本文系统梳理硅基集成外腔可调谐窄线宽激光器的最新研究进展。首先详细阐述硅基集成外腔激光器的工作原理与结构特征，分析技术特点与性能优势。接着回顾硅基集成外腔激光器技术的发展历程，对比激光器的性能指标和最新技术突破，展现技术进步的速度与方向。随后展示了激光器在相干光通信、激光雷达、微波光子等前沿领域的具体应用案例与性能表现。最后对未来发展趋势进行展望，探讨在集成工艺、性能突破、功能创新、系统应用等方面可能出现的突破方向。更多还原

【Abstract】 Significance Tunable narrow-linewidth lasers,as one of the core components in modern high-precision optoelectronic systems,have revolutionized many fields including coherent optical communication,Li DAR,microwave photonics and precision metrology.With the trends of high precision and high capacity in modern massive optoelectronic technologies,integrated light sources are required to simultaneously exhibit ultra-narrow linewidth,wide-range tunability,and high-speed operation,which puts forward higher and stricter technical requirements.Traditional chip-scale semiconductor laser technologies have become relatively mature over decades.However,their applicability in high-precision coherent systems is fundamentally constrained by limited photon lifetime and significant carrier-induced nonlinear effects.With the boom in silicon photonics,silicon-based integrated external-cavity lasers （Si-IECLs） have emerged as promising chipscale light sources.By combining matureⅢ-Ⅴgain materials with ultra-low-loss external cavities on various integrated photonic platforms,this family of lasers has the potential to surpass traditional semiconductor lasers and even bench-top lasers in terms of coherence,tunability,and agility.Si-IECLs have attracted considerable attention over the past decade,and various architectures and platforms have been introduced and demonstrated in this field to provide remarkable progress in terms of laser performance.We highlight the integration of semiconductor lasers with emerging platforms such as silicon,silicon nitride （Si₃N₄）,and lithium niobate on insulator （LNOI）,and the functionality extension in frequency-modulated continuous-wave （FMCW） generation,frequency stabilization,and ultrafast switching capabilities.Therefore,it is important to summarize the existing research to guide the future development of this field.Progress Si-IECLs are classified into three structural categories:Vernier ECLs,self-injection locked （SIL） lasers,and extended distributed Bragg reflector （E-DBR） lasers.The development of these lasers has advanced along two main trajectories:the introduction of novel external cavity platform systems for performance enhancement and the adoption of advanced integration processes to improve integration density and large-scale manufacturing capabilities.Vernier ECLs adopt high-Q cascaded microring resonators （MRRs） with the Vernier effect,which are coupled to aⅢ-Ⅴgain chip,providing both wavelength tunability and linewidth reduction.Vernier ECLs stand out because of their ultra-wide tunability,which has achieved a record tuning range of 172 nm.In terms of linewidth performance,Vernier ECLs reach intrinsic linewidths at the sub-10 Hz level.Moreover,benefiting from the fast tuning mechanisms of external cavity,they support rapid wavelength switching and FMCW generation.A SIL laser employs a high-Q MRR to provide feedback for a single-frequency semiconductor laser.Thus,the laser is adaptively locked to the resonance peak of the MRR,achieving a considerable linewidth reduction.So far,studies on SIL lasers have reported a record intrinsic linewidth of 40 m Hz that reaches the fiber-laser level.Leveraging the tuning mechanisms and nonlinearity in the external cavity,SIL lasers can generate FMCW light and soliton microcomb,respectively.An E-DBR utilizes a distributed Bragg grating coupled to aⅢ-Ⅴgain chip,featuring structural and operational simplicity.It holds a unique advantage in FMCW generation,with reported tuning speeds up to 1 GHz and chirp rates reaching 20 EHz/s,which are the highest results among FMCW lasers to date to the best of our knowledge.Advances in heterogeneous integration technology have also led to the development of various fully integrated lasers,driving large-scale manufacturing of these devices.Benefiting from the high coherence,wide tunability,and diverse functionality,Si-IECLs enable numerous applications that require high-accuracy,highly stable optical signals.For coherent optical communications,they support a high modulation rate in numerous wavelength-division multiplexing channels.In addition,these lasers leverage the ultrafast wavelength switching capability for wavelength routing in low-latency optical circuit switching.In Li DAR systems,Si-IECLs are ideally suitable for FMCW Li DAR architectures.Their narrow linewidth and large tuning range significantly enhance the sensitivity and precision of coherent detection,while the synergy between wide tunability and optical phased arrays enables two-dimensional beam scanning.In microwave photonics,the narrow linewidth of Si-IECLs facilitates low-phase-noise microwave generation,and their wide tunability supports broadband signal generation and frequency measurement.Conclusions and Prospects Si-IECLs have achieved remarkable breakthroughs,demonstrating comprehensive advantages over traditional semiconductor lasers in both performance metrics and functionality extension.So far,Si-IECLs have demonstrated a record tuning range up to 172 nm,ultra-low linewidth down to fiber-laser level,and ultra-high operation speed up to 1 GHz.Such advances in integrated light sources have dramatically promoted the development of on-chip photonics systems for diverse application scenarios,such as coherent optical communications,Li DAR,and microwave photonics.Looking forward,Si-IECLs still face numerous challenges and development opportunities.Technically,further optimization of heterogeneous integration processes is needed to improve device consistency and yield rates while reducing manufacturing costs,thereby promoting the transition from laboratory demonstrations to industrial production.In terms of functional expansion,lasers will undergo cross-platform large-scale integration with active/passive devices,including modulators and detectors,to form multifunctional photonic chips.Furthermore,next-generation Si-IECLs are expected to play key roles not only in enhancing system performance in high-speed communications,precision measurement,and sensing fields,but also in emerging areas such as quantum information processing,biomedical sensing,and artificial intelligence computing.更多还原