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A Talk by Assistant Research Professor Hossein Taheri

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Winston Chung Hall 205/206 - Winston Chung Hall

MINIATURIZED SOURCES OF ULTRASHORT OPTICAL PULSES AND HIGH SPECTRAL PURITY MICROWAVE SIGNALS

A train of ultrashort optical pulses is comprised of a large number of laser tones oscillating synchronously. This
equally-spaced array of frequencies, called an optical frequency comb, has found applications in the generation
of high spectral purity microwave signals, sensing and spectroscopy, calibration of astronomical spectrograms
and search for exoplanets, timekeeping and the most accurate clocks, self-driving cars and LIDAR, and the
precise measurement of some of the fundamental physical constants of the universe. Owing to its far-reaching
applications, the frequency comb technology was recognized by the 2005 Nobel Prize in Physics. While optical
frequency combs were originally realized by femtosecond mode-locked laser sources, in the past decade their
demonstration in micron-scale and chip-based optical resonators made from Kerr-nonlinear materials bears the
promise of simplifying their various applications and increasing their versatility by making them available at
significantly reduced cost, size, and weight. The goal of my research is to provide a fundamental understanding
of the process of frequency comb formation in nonlinear media and addressing the practical challenges posed
by platform miniaturization in microresonator-based optical frequency comb (microcomb) generation. In this
talk, I will highlight my research on the deterministic generation of stable ultrashort pulses (temporal solitons)
in integrated photonic platforms, wavelength-specific engineering of microresonator structures for broadband
microcomb generation, and innovative techniques for addressing the long-standing problem of stabilization of
small-bandwidth microcombs for low phase noise radio-frequency (RF) signal generation and use in optical
atomic clocks. I will also talk about some new directions of research in my lab at UC Riverside geared towards
using frequency combs for early diagnosis of medical complications in the eye.

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Target Audience
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Admission
Free
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