Optical switch and display unit

摘要

The present invention provides an optical switch for making part of incident light, which has been made incident on an optical waveguide, selectively emergent to a light emergence portion provided outside the optical waveguide. The optical switch includes a liquid crystal device for selective emergence of the incident light. An arbitrary layer of the liquid crystal device is set such that letting Deltan be a difference between a refractive index n_o of the optical waveguide and a refractive index n₁ of the arbitrary layer of the liquid crystal device, "d" be a thickness of the arbitrary layer, and lambda be a wavelength of the incident light, the values of Deltan, "d", and lambda satisfy a condition of 2.20x10^-3<=|Deltan.d.lambda^-1|<=3.03x10^-3. With this optical switch, the uniformity of a light emergence efficiency can be easily realized by making use of a small change region in which the light emergence efficiency is not largely varied. The present invention also provides a display unit using the optical switches.