PURPOSE: To allow high-efficiency optical coupling and to perform stable fixation by using an integral type prism for optical coupling which is separated into a prism part for light guiding and the prism part for optical coupling which has an obtuse angle as one vertical angle.
CONSTITUTION: Incident light 5 is sent to the prism part 3a for light guiding, and then sent to an optical coupling surface after surface refraction. The coupling surface 8 is one slanting surface of the prism part 11 for coupling, and the incident light 5 is converted by this coupling surface 8 into evanescent light, which is sent to a photoconduction part 2. A vertical angle 9 is so selected that a gap 10 for adjustment is present between the opposite-side slanting surface of the prism part 11 for optical coupling and the photoconduction part 2. The vertical angle 9 is shifted in position to vary the length of the coupling surface according to the diameter of the incident light and the precision of the substrate surface, so that the precision of the substrate surface is less required than before. The gap 10 is charged with a photocuring agent, etc., to perform adhesion with large strength. The contact point 9 is one obtuse vertical angle, so the prism is thick at this point and an excellent tapered air gap 4 is formed, obtaining extremely excellent transmission efficiency.
KAWAGUCHI TAKAO
SETSUNE KENTAROU
