Yuen-Ron Shen (Chinese: 沈元壤; pinyin: Shěn Yuánrǎng) is a Chinese physicist. He is a professor emeritus of physics at the University of California, Berkeley, known for his work on non-linear optics. He was born in Shanghai and graduated from National Taiwan University. He received his Ph.D. in Applied Physics from Harvard under physicist and Nobel Laureate Nicolaas Bloembergen in 1963, and joined the department of physics at Berkeley in 1964. In the early years, Shen was probably best known for his work on self-focusing and filament propagation of laser beams in materials. These fundamental studies enabled the creation of ultrafast supercontinuum light sources. In the 1970s and 1980s, he collaborated with Yuan T. Lee on the study of multiphoton dissociation of molecular clusters. The molecular-beam photofragmentation translational spectroscopy that they developed has clarified much of the initial confusion concerning the dynamics of infrared multiphoton dissociation processes. In the 1980s and 1990s, Shen developed various nonlinear optics methods for the study of material surfaces and interfaces. Among these techniques, second-harmonic generation and sum frequency generation spectroscopy are best known and now widely used by scientists from various fields. He has collaborated with Gabor Somorjai on the use of the technique of Sum Frequency Generation Spectroscopy to study catalyst surfaces. He is the author of the book The Principles of Nonlinear Optics. Shen belongs to the prolific J. J. Thomson academic lineage tree. Currently, Shen works in U. C. Berkeley and Fudan University in Shanghai.