Abstract: A device has a plurality of waveguide structures including two active (one of which comprises two sub-layers), two passive, and three intermediate waveguide structures on a common substrate. At least partial butt coupling between active and intermediate waveguide structures, and tapering in the intermediate and/or passive waveguide structures at each junction therebetween facilitates efficient optical mode transformations as optical signals travel through the device, either from a first sub-layer of the first active waveguide structure through the other sub-layer, then sequentially though a first intermediate waveguide structure, a passive waveguide structure, a second intermediate waveguide structure, a second active waveguide structure, a third intermediate structure, and a second passive waveguide structure; or in reverse from the second passive waveguide structure back through to the first sub-layer of the first active waveguide structure.

Abstract: A device includes a module comprising an arrayed waveguide grating (AWG), and a filter having a filter input port, a filter output port, and a filter COMM output port. The filter is operable such that a first range of wavelengths entering the filter at the filter input port is directed to the filter output port and a second range of wavelengths entering the filter at the filter input port is directed to the COMM output port. The AWG includes an AWG input port optically coupled to the filter output port to receive the first range of wavelengths, and a plurality of AWG output ports.

Abstract: An optical device comprises first, second and third elements fabricated on a common substrate. The first element comprises an active waveguide structure supporting a first optical mode, the second element, fabricated on a planarized top surface of the first element, comprises a passive waveguide structure supporting a second optical mode, and the third element, at least partly butt-coupled to the first element, comprises an intermediate waveguide structure, positioned such that a top surface of the intermediate structure underlies a bottom surface of the passive waveguide structure. If the first optical mode differs from the second optical mode by more than a predetermined amount, a tapered waveguide structure in at least one of the second and third elements facilitates efficient adiabatic transformation between the first optical mode and the second optical mode. Mutual alignments of the first, second and third elements are defined using lithographic alignment marks.

Abstract: A device comprises first, second and third elements fabricated on a common substrate. The first element comprises an active waveguide structure comprising: one portion, of effective cross-sectional area A1, supporting a first optical mode; and a second portion, butt-coupled to the first portion, of effective cross-sectional area A2>A1. The second element comprises a passive waveguide structure supporting a second optical mode. The third element, at least partly butt-coupled to the second portion, comprises an intermediate waveguide structure supporting intermediate optical modes. If the first optical mode differs from the second optical mode by more than a predetermined amount, a tapered waveguide structure in at least one of the second and third elements facilitates efficient adiabatic transformation between the first optical mode and one intermediate optical mode. No adiabatic transformation occurs between any intermediate optical mode and the first optical mode.

Abstract: An optical device comprises first, second and third elements fabricated on a common substrate. The first element comprises an active waveguide structure supporting a first optical mode, the second element comprises a passive waveguide structure supporting a second optical mode, and the third element, at least partly butt coupled to the first element, comprises an intermediate waveguide structure supporting intermediate optical modes. If the first optical mode differs from the second optical mode by more than a predetermined amount, a tapered waveguide structure in at least one of the second and third elements facilitates efficient adiabatic transformation between the second optical mode and one of the intermediate optical modes. No adiabatic transformation occurs between any of the intermediate optical modes and the first optical mode. Mutual alignments of the first, second and third elements are defined using lithographic alignment marks.

Abstract: An optical apparatus includes a waveguide-based frequency-selective structure with one or more input ports and N1 output ports where N1 is 2 or more. If input signals in a pair of input signals are separated in frequency by an integer multiple of the structure's free spectral range, and one of the pair is routed onto one output port, the other in the pair is also routed onto that port. The apparatus also includes: N2 waveguides, where N2<=N1, each having an input port coupled to a corresponding one of the N1 output ports, and a waveguide output port; N3 frequency-selective elements where N3<=N2, each having an input port coupled to a corresponding one of the N2 waveguide output ports and an output surface from which optical emission occurs at an optical frequency-dependent angle; and an element receiving optical emission from the N3 output surfaces, detecting a corresponding intensity pattern.

Abstract: An optical device comprises first, second and third elements fabricated on a common substrate. The first element comprises an active waveguide structure supporting a first optical mode, the second element comprises a passive waveguide structure supporting a second optical mode, and the third element, at least partly butt coupled to the first element, comprises an intermediate waveguide structure. If the first optical mode differs from the second optical mode by more than a predetermined amount, a tapered waveguide structure in at least one of the second and third elements facilitates efficient adiabatic transformation between the first optical mode and the second optical mode. Mutual alignments of the first, second and third elements are defined using lithographic alignment marks.