Abstract: Roughly described, an optical device includes a first waveguide having a first core sheathed by a first cladding, and a second waveguide having a second core. A terminal portion of second core is disposed under a terminal portion of the first core and sheathed by the first core. The refractive index of the second core is higher than that of the first core, and the index of the first core, at least in the terminal portion of the first waveguide, is higher than that of the first cladding. The second core is structured under the terminal portion of the first core so that light traveling in the second core and directed toward the end of the second core is guided along the second core and coupled into the first core, and vice-versa.

Abstract: An optical coupler couples light from waveguides of a photonic integrated circuit (PIC) to output waveguides, for example waveguides of a planar lightwave circuit (PLC). The optical coupler includes optical elements having different optical properties. In some embodiments the optical properties vary to account for waveguide angled facets in the PIC, and in some embodiments the optical properties vary to account for the PIC being mounted at an angle compared to the PLC, or optical coupler.

Abstract: An optical transceiver may include a circuit board, lasers, and a PLC including optical multiplexers and demultiplexers. The PLC may be coupled to fiber optic lines at a forward edge of the PLC, with a rear edge of the PLC receiving light for transmission generated by the lasers. Light received at the forward edge of the PLC may be demultiplexed into data channels and routed to a top surface of the PLC for optoelectronic conversion by photodetectors. In some embodiments each data channel is routed into a corresponding plurality of waveguides, with each of the corresponding plurality of waveguides providing light to the same photodetector. In some embodiments at least some receive side electronic circuitry, other than photodetectors, is stacked on top of the PLC.

Abstract: Roughly described, an optical device includes a first waveguide having a first core sheathed by a first cladding, and a second waveguide having a second core. A terminal portion of second core is disposed under a terminal portion of the first core and sheathed by the first core. The refractive index of the second core is higher than that of the first core, and the index of the first core, at least in the terminal portion of the first waveguide, is higher than that of the first cladding. The second core is structured under the terminal portion of the first core so that light traveling in the second core and directed toward the end of the second core is guided along the second core and coupled into the first core, and vice-versa.

Abstract: An arrayed waveguide grating (AWG) device comprising a substrate having a first array of waveguides optically coupled between first and second slab couplers and a second array of input-output waveguides optically coupled at first ends thereof to an input/output side of the second slab-coupler. The input/output waveguide are tapered at first end portions thereof so as to increase in width towards the second slap coupler, and the width (W) of the first ends of the input/output waveguides varies across the second array in a manner so as to increase uniformity of at least on performance parameter, for example adjacent crosstalk (AXT). In the described embodiment, the width (W) of the tapered waveguide ends increases from one side to the array of input/output waveguides to the other, so as to keep the separation(s) between the input/output waveguides.