{"id":2782,"date":"2026-02-05T15:38:29","date_gmt":"2026-02-05T15:38:29","guid":{"rendered":"https:\/\/cleoconference.org\/?page_id=2782"},"modified":"2026-02-05T15:38:29","modified_gmt":"2026-02-05T15:38:29","slug":"ursula-keller","status":"publish","type":"page","link":"https:\/\/cleoconference.org\/ursula-keller\/","title":{"rendered":"Ursula Keller"},"content":{"rendered":"

Short Course<\/h2><\/div>

CLEO<\/h2><\/div>

The premier international forum for scientific and technical optics.<\/em><\/p>\n<\/div>

REGISTER NOW<\/span><\/a><\/div><\/div><\/div><\/div><\/div>

Ursula Keller<\/span><\/span>\u00a0<\/span><\/p><\/h3><\/div>

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Course\u202fTitle:<\/strong>Ultrafast Lasers<\/span><\/span><\/span><\/p>\n

Course\u202fLevel:<\/strong> From beginner to advanced<\/span><\/span>\u00a0<\/span><\/span><\/p>\n

Course\u202fDescription:<\/strong><\/span><\/p>\n

his short course reviews the core physics and practical design rules of modelocked lasers\u00a0<\/span>with analytical models\u00a0<\/span>and explains why they enabled many of today\u2019s key advances in ultrafast science. Following the time\u2013frequency duality, we develop an intuitive and quantitative view of<\/span>\u00a0ultrashort pulse generation with modelocking<\/span>.<\/span>\u00a0<\/span>We cover<\/span>\u00a0both active modelocking\u00a0<\/span>(Siegman\u2013Haus theory) and<\/span>\u00a0passive modelocking<\/span>, including cases with and without dynamic gain saturation. A dedicated section addresses real-world stability\u00a0<\/span>issues<\/span>: self-starting behavior, Q-switching instabilities, long open net-gain windows, and excess self-phase modulation (SPM), with practical mitigation strategies.<\/span>\u00a0Noise is explained with regards to power spectral densities.\u00a0<\/span>For passive modelocking, we compare<\/span>\u00a0fast and slow saturable absorbers, soliton modelocking<\/span>, and introduce<\/span>\u00a0semiconductor saturable absorber mirror (SESAM) design principles<\/span>\u00a0<\/span>that link absorber parameters to starting behavior, noise, and scaling limits. We then connect modelocked lasers to<\/span>\u00a0frequency combs<\/span>, including carrier-envelope offset (CEO) phase<\/span>\u00a0measurement<\/span>\u00a0and stabilization.<\/span>\u00a0<\/span>The course concludes with performance scaling trends (pulse duration, average power, repetition rate, and noise) and emerging opportunities such as<\/span>\u00a0dual-comb modelocking<\/span>\u00a0<\/span>and applications in optical communications, positioned for participants attending Conference on Lasers and Electro-Optics (CLEO).<\/span><\/span>\u00a0<\/span><\/p>\n

Benefits\u202fand\u202fLearning\u202fObjectives:<\/strong>\u00a0<\/span><\/p>\n

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  • Explain the physical motivation and basic principles of active and passive modelocking.<\/span>\u00a0<\/span><\/li>\n<\/ul>\n
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    • Use analytical models (including Siegman\u2013Haus and soliton concepts) to understand parameter scaling and design trade-offs.<\/span>\u00a0<\/span><\/li>\n<\/ul>\n
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      • Design cavity, gain, dispersion, and nonlinear parameters to achieve robust self-starting, stable modelocking.<\/span>\u00a0<\/span><\/li>\n<\/ul>\n
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        • Specify and optimize saturable absorber parameters for stability and scalability, using SESAM design rules transferable to emerging absorber materials.<\/span>\u00a0<\/span><\/li>\n<\/ul>\n
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          • Diagnose and mitigate common instabilities (Q-switching, long net-gain window effects, excess SPM) and their practical limits.<\/span>\u00a0<\/span><\/li>\n<\/ul>\n
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            • Measure and interpret laser noise using power spectral densities, and connect noise metrics to system performance.<\/span>\u00a0<\/span><\/li>\n<\/ul>\n
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              • Relate modelocked lasers to frequency comb operation, including CEO concepts and stabilization requirements.<\/span>\u00a0<\/span><\/li>\n<\/ul>\n
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                • Identify the current performance frontier and evaluate new opportunities such as dual-comb modelocking and optical communication applications.<\/span>\u00a0<\/span><\/li>\n<\/ul>\n

                  \u00a0<\/span><\/p>\n

                  Intended\u202fAudience:<\/strong><\/p>\n

                  This short course is intended for graduate students, researchers, and industry engineers who want a clear physical introduction to modelocking and frequency combs. It emphasizes core concepts, intuition, and practical design trade-offs rather than long derivations. Participants seeking step-by-step mathematical treatments can refer to my textbook<\/span>\u202f<\/span><\/span>Ultrafast Lasers<\/span><\/span>\u202f<\/span>(Springer, 2021). The course provides a foundation to scale ultrafast laser performance and to identify new regimes and applications.<\/span><\/span>\u00a0<\/span><\/p>\n

                  Instructor\u202fBiography:\u00a0<\/strong><\/p>\n

                  Professor Ursula Keller is Emeritus Professor of Physics at ETH Zurich (1993\u20132025) with over 30 years of teaching experience and author of the graduate textbook<\/span>\u202f<\/span><\/span>Ultrafast Lasers<\/span><\/span>\u202f<\/span>(Springer, 2021).\u00a0<\/span>She supervised 101 PhD students<\/span>\u00a0and published >500 papers<\/span>.\u00a0<\/span>She pioneered key advances in ultrafast solid-state and semiconductor lasers, including SESAMs, single-cycle pulse generation,\u00a0<\/span>and\u00a0<\/span>frequency-comb stabilization. She co-founded several start-ups and has received major international honors, including the\u00a0<\/span>European inventor award,\u00a0<\/span>IEEE Edison Medal, OSA Ives Medal, SPIE Gold Medal,\u00a0<\/span>NAS and FRS membership.\u00a0<\/span><\/span>\u00a0<\/span><\/p>\n<\/div><\/div><\/div>

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