Optical energy-based methods and apparatus for sealing vascular tissue involves deforming vascular tissue to bring different layers of the vascular tissue into contact each other and illuminating the vascular tissue with a light beam having at least one portion of its spectrum overlapping with the absorption spectrum of the vascular tissue. The apparatus may include two deforming members configured to deform the vascular tissue placed between the deforming members. The apparatus may also include an optical system that has a light source configured to generate light, a light distribution element configured to distribute the light across the vascular tissue, and a light guide configured to guide the light from the light source to the light distribution element. The apparatus may further include a cutting member configured to cut the vascular tissue and to illuminate the vascular tissue with light to seal at least one cut surface of the vascular tissue.
