Optical signal coupling apparatus

An optical coupler is provided which includes a transmitter optical cable which is machined along its length to have a substantially flat, smooth lower surface. The transmitter optical cable includes a curved upper surface on which a cladding layer is situated for containing an optical signal which is provided to an input end of the transmitter optical cable. A receiver optical cable is similarly machined to include a substantially flat, smooth upper surface and a curved lower surface on which a cladding layer is situated. The flat lower surface of the transmitter optical cable and the flat upper surface of the receiver optical cable are oriented in generally parallel, spaced apart relationship with an index matching member being situated therebetween. An incident optical signal enters the input end of the transmitter optical cable, exits the lower surface thereof, enters the index matching member and the upper surface of the receiver optical cable, and exits the output end thereof. I