and a Professor of Physics. In collaboration with Michael A. Choma at Yale medical school, she applied her understanding of random lasing systems to the design of novel illumination sources for speckle-free imaging. In conventional lasers, high spatial coherence can result in artefacts such as speckle noise, which can compromise full-field imaging. While having similar brightnesses to conventional lasers, random lasers can have low spatial coherence like light emitting diodes (LEDs) and avoid speckle noise in full-field imaging and parallel projection. Random lasers are simple to fabricate, as they are made of disordered materials. Cao also developed the light sources for optical coherence tomography for biomedical applications. She designed a novel laser system that can switch between high and low spatial coherence, allowing for both speckle-free imaging (to monitor the structure of an object) and speckle-full imaging (to track the motion of an object). She applied such a laser to imaging the heartbeat of a living tadpole, which is an animal model of human heart disease. In addition, Cao studied other types of non-conventional lasers, including chaotic microcavity lasers, deterministic aperiodic lasers, photonic amorphous lasers, and topological defect lasers. She worked with A. Douglas Stone on a new mathematical theory to model such laser systems. Cao and Stone were the first researchers to create an anti-laser; a device in which incoming beams of light interfere with one another and cancel the outgoing waves. Cao dubbed these devices coherent perfect absorbers (CPAs), and proposed that they can be used as optical switches and radiology. She also showed that it is possible to control light transmission and absorption in opaque media by shaping the spatial wavefronts of laser beams. After moving to Yale, Cao started the biophotonics program and established collaborations with several biologists and material scientists. In collaboration with Richard Prum and Eric Dufresne, she figured out how the vivid color of bird feather is produced by nanostructures instead of pigments. Together with Antonia Monterio, Cao studied the evolution of the structural color and how it is affected by the environment. She was able to control lasing in biomimetic structures with short-range order. In 2012 Cao demonstrated that a multimode fiber can function as an ultra-high-resolution broadband spectrometer. The speckle pattern, generated by interference among the guided modes in a fiber, is unique for each wavelength and can be used as a fingerprint to identify the spectral content of the input