Optical waveguide splitter on a waveguide substrate for attenuating a light source

An optical apparatus comprising:

• a waveguide substrate;
• one or more optical waveguide layers on the substrate;
• source, primary, and secondary optical waveguides formed in one or more of the optical waveguide layers, each of the optical waveguides being arranged to substantially confine in two transverse dimensions a corresponding guided optical mode;
• a light source that emits an optical signal and is arranged to launch a portion of the optical signal to propagate along the source waveguide as a source optical signal in the corresponding guided optical mode;
• and
• a first optical waveguide tap formed in one or more of the optical waveguide layers and arranged to direct a primary fraction of the source optical signal to propagate along the primary waveguide as a primary optical signal and to direct a secondary fraction of the source optical signal to propagate along the secondary waveguide as a secondary optical signal,
• wherein the secondary waveguide is arranged so that the secondary optical signal propagates to an end of the secondary waveguide and emerges from transmissive lateral surfaces of the optical waveguide layers at the edge of the waveguide substrate.

A method for making an optical apparatus, the method comprising:

• forming source, primary, and secondary optical waveguides in one or more optical waveguide layers formed on a waveguide substrate;
• arranging a light source to launch a source optical signal to propagate along the source waveguide in the corresponding guided optical mode;
• and
• forming an optical waveguide tap in one or more of the optical waveguide layers and arranging the tap to direct a primary fraction of the source optical signal to propagate along the primary waveguide as a primary optical signal and to direct a secondary fraction of the source optical signal to propagate along the secondary waveguide as a secondary optical signal,
• wherein the secondary waveguide is arranged so that the secondary optical signal propagates to an end of the secondary waveguide and emerges from transmissive lateral surfaces of the optical waveguide layers at the edge of the waveguide substrate.

A method for using an optical apparatus, the method comprising:

• operating a light source to launch a source optical signal to propagate along a source waveguide in a corresponding guided optical mode;
• directing a primary fraction of the source optical signal to propagate along a primary waveguide as a primary optical signal in a corresponding guided optical mode;
• directing a secondary fraction of the source optical signal to propagate along and to an end of a secondary waveguide as a secondary optical signal in a corresponding guided optical mode;
• and
• discarding the secondary optical signal by directing the secondary optical signal to emerge from transmissive lateral surfaces of optical waveguide layers at an edge of a waveguide substrate,
• wherein the optical apparatus comprises:
• the waveguide substrate;
• the one or more optical waveguide layers on the substrate;
• the source optical waveguide, the primary optical waveguide, and the secondary optical waveguide formed in one or more of the optical waveguide layers, each of the optical waveguides being arranged to substantially confine in two transverse dimensions a corresponding guided optical mode;
• the light source;
• and
• a first optical waveguide tap formed in one or more of the optical waveguide layers and arranged to direct the primary fraction of the source optical signal to propagate along the primary waveguide as the primary optical signal and to direct the secondary fraction of the source optical signal to propagate along the secondary waveguide as the secondary optical signal.