Illumination device having a light guide with leaky side surfaces

An illumination device comprising:

• one or more light-emitting elements (LEEs) arranged to provide light;
• a light guide comprising
• a receiving end and an opposing end, the receiving end arranged to receive the light provided by the LEEs, and
• a pair of opposing side surfaces extending along a length of the light guide between the receiving end and the opposing end, the light guide configured to
• guide the received light in a forward direction, along the length of the light guide toward the opposing end of the light guide, and
• transmit a first portion of the guided light into ambient environment through one or more of the opposing side surfaces as sideways leaked light;
• and
• an optical extractor located at the opposing end and configured to output into the ambient environment a remaining portion of the guided light—that reaches the opposing end—as output light in backward directions,
• wherein the light guide is tapered such that
• a receiving aperture at the receiving end of the light guide is larger than an output aperture at the opposing end,
• an angle of incidence of guided light incident on the opposing side surfaces exceeds a critical angle beyond a predetermined distance from the receiving end, and
• some of the light guided beyond the predetermined distance transmits into the ambient environment through the opposing side surfaces as the sideways leaked light.