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1. Near-Visible Microresonator-Based Soliton Combs

   https://doi.org/10.1364/CLEO_SI.2019.STh3J.1  

   Zhao, Yun; Ji, Xingchen; Kim, Bok Young; Donvalkar, Prathamesh; Jang, Jae; Joshi, Chaitanya; Yu, Mengjie; Domeneguetti, Renato R.; Barbosa, Felippe A.; Nussenzveig, Paulo; et al (January 2019, Conference on Lasers and Electro-Optics)

   We experimentally demonstrate soliton mode-locked Kerr comb generation at near-visible wavelengths in a silicon nitride microresonator. We achieve the shortest wavelength to-date for mode-locked Kerr combs through dispersion engineering of a higher-order mode. 

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2. Complex Swift Hohenberg equation dissipative soliton fiber laser

   https://doi.org/10.1364/PRJ.419686  

   Khanolkar, Ankita; Zang, Yimin; Chong, Andy (May 2021, Photonics Research)

   Complex Swift Hohenberg equation (CSHE) has attracted intensive research interest over the years, as it enables realistic modeling of mode-locked lasers with saturable absorbers by adding a fourth-order term to the spectral response. Many researchers have reported a variety of numerical solutions of CSHE which reveal interesting pulse patterns and structures. In this work, we have demonstrated a CSHE dissipative soliton fiber laser experimentally using a unique spectral filter with a complicated transmission profile. The behavior and performance of the laser agree qualitatively with the numerical simulations based on CSHE. Our findings bring insight into dissipative soliton dynamics and make our mode-locked laser a powerful testbed for observing dissipative solitons of CSHE, which may open a new course in ultrafast fiber laser research. 

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3. Multimode nonlinear dynamics in spatiotemporal mode-locked anomalous-dispersion lasers

   https://doi.org/10.1364/OL.471457  

   Wu, Yuhang; Christodoulides, Demetrios_N; Wise, Frank_W (August 2022, Optics Letters)

   Spatiotemporal mode-locking in a laser with anomalous dispersion is investigated. Mode-locked states with varying modal content can be observed, but we find it difficult to observe highly-multimode states. We describe the properties of these mode-locked states and compare them to the results of numerical simulations. Prospects for the generation of highly-multimode states and lasers based on multimode soliton formation are discussed. 

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4. Electrically empowered microcomb laser

   https://doi.org/10.1038/s41467-024-48544-2  

   Ling, Jingwei; Gao, Zhengdong; Xue, Shixin; Hu, Qili; Li, Mingxiao; Zhang, Kaibo; Javid, Usman A; Lopez-Rios, Raymond; Staffa, Jeremy; Lin, Qiang (December 2024, Nature Communications)

   Abstract Optical microcomb underpins a wide range of applications from communication, metrology, to sensing. Although extensively explored in recent years, challenges remain in key aspects of microcomb such as complex soliton initialization, low power efficiency, and limited comb reconfigurability. Here we present an on-chip microcomb laser to address these key challenges. Realized with integration between III and V gain chip and a thin-film lithium niobate (TFLN) photonic integrated circuit (PIC), the laser directly emits mode-locked microcomb on demand with robust turnkey operation inherently built in, with individual comb linewidth down to 600 Hz, whole-comb frequency tuning rate exceeding 2.4 × 10¹⁷ Hz/s, and 100% utilization of optical power fully contributing to comb generation. The demonstrated approach unifies architecture and operation simplicity, electro-optic reconfigurability, high-speed tunability, and multifunctional capability enabled by TFLN PIC, opening up a great avenue towards on-demand generation of mode-locked microcomb that is of great potential for broad applications. 

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5. A 49-63 GHz Phase-locked FMCW Radar Transceiver for High Resolution Applications

   Liu, Xuyang; Maktoomi, Md Hedayatullah; Alesheikh, Mahdi; Heydari, Payam; Aghasi, Hamidreza (October 2023, IEEE European Solid State Circuits Conference)

   TPC of IEEE ESSCIRC Conference (Ed.)

   This paper presents an mmWave FMCW radar that can achieve sub-centimeter-scale range resolution at 14- GHz chirp-bandwidth while maintaining the radar range beyond 50 meters. To meet the requirements on power efficiency, chirp linearity, and signal-to-noise ratio (SNR), a phase-locked steppedchirp FMCW radar architecture is introduced. Specifically, a fully integrated radar transceiver comprising an interleaved frequency-segmented phase-locked transmitter and a segmented receiver architecture with high sensitivity is presented. The proposed design addresses the limitations of conventional typeII phase-locked loops (PLLs) in extending the radar bandwidth across multiple sub-bands with identical chirp profiles. Fabricated in a 22nm FD-SOI technology, the prototype chip comprises two sub-bands with 14 GHz of free-running bandwidth and 10 GHz of phase-locked bandwidth. The system achieves -101.7 dBc/Hz phase noise at 1 MHz offset, 8 dBm of effective isotropic radiated power (EIRP), 10 dB noise figure (NF), and 362.6 mW collective power consumption of transmitter and receiver arrays. 

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