The invention of lasers 60 years ago is one of the greatest breakthroughs in modern optics. Throughout the years, lasers have enabled major scientific and technological advancements, and have been exploited in numerous applications due to their advantages such as high brightness and high coherence. However, the high spatial coherence of laser illumination is not always desirable, as it can cause adverse artifacts such as speckle noise in imaging applications. To reduce the spatial coherence of a laser, we have developed novel cavity geometries and alternative feedback mechanisms. By tailoring the spatial and spectral properties of cavity resonances, we are able to tune the degree of first-order coherence. This talk presents an overview of these unconventional, complex lasers, with a focus on their spatial coherence properties. Such lasers have been applied to speckle-free full-field imaging, bimodal microscopy, and parallel optical coherence tomography.

Complex Lasers
Hui Cao
Dept. of Applied Physics, Yale University, New Haven, CT 06511
hui.cao@yale.edu