Optical element having inclined surface

#The present invention relates to an optical element, such as a gradient-index rod-lens and a capillary. More particularly, the present invention pertains to an optical element having at least one end surface that is inclined with respect to a central axis of the rod lens or the capillary.

#A typical gradient-index rod-lens converts light that is sent from a light source, such as a laser diode and a light emitting diode (LED), to a parallel light or converges light that is received through an optical fiber at a predetermined position- To transmit light from one optical fiber to another, two rod lenses are arranged to contact each other Alternatively, a filter, which has desired optical characteristics, is placed between two rod lenses. The lens length of the rod lens is determined according to the intended purpose of the rod lens. For example, the lens length of the rod lens is set in accordance with the distance between the output end of the optical fiber and the rod lens or the distance between the two rod lenses such that the coupling loss is minimized.

#FIG. 6 illustrates conventional rod lenses 60, 61 used in an optical communication module. The rod lens 60 on the left side has an output side end surface 60a, which is inclined with respect to a central axis C1 of the rod lens 60. The rod lens 61 on the right side has an input side end surface 61a, which is inclined with respect to a central axis C2 of the rod lens 61.

#The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

#FIG. 1 is a side view illustrating a rod lens according to the preferred embodiment of the present invention;

#FIG. 2 is a front view illustrating the rod lens shown in FIG. 1;

#An optical element having an inclined surface according to a preferred embodiment of the present invention will now be described with reference to FIGS. 1 to 4.

#In this specification, a term “optical element” includes a gradient-index rod-lens, a capillary, which holds an optical fiber, and an optical member such as an optical crystal used for, for example, an optical isolator. Also, in this specification, a term “effective diameter of a rod lens” refers to the maximum diameter of a lens that provides an optical aberration that is less than or equal to a predetermined value.

#A gradient-index rod-lens 11 according to the preferred embodiment of the present invention will now be described with reference to FIGS. 1 and 2. FIG. 2 is a view looking at the rod lens 11 shown in FIG. 1 from a direction indicated by an arrow A.