Optical waveguides and couplers for delivering light to an array of photonic elements in a photonic integrated device. The photonic integrated device and related instruments and systems may be used to analyze samples in parallel. The photonic integrated device may include a grating coupler configured to receive light from an external light source and optically couple with multiple waveguides configured to optically couple with sample wells of the photonic integrated device.

Optical waveguides and couplers for delivering light to an array of photonic elements in a photonic integrated device. The photonic integrated device and related instruments and systems may be used to analyze samples in parallel. The photonic integrated device may include a grating coupler configured to receive light from an external light source and optically couple with multiple waveguides configured to optically couple with sample wells of the photonic integrated device.

An optical coherent transceiver comprising a polarization and phase-diversity coherent receiver and a polarization and phase-diversity modulator on the same substrate interfaced by three grating couplers, one grating coupler coupling in a signal, one grating coupler coupling in a laser signal, and a third grating coupler coupling out a modulated signal.

An optical circuit for routing a signal includes a coupler and first and second waveguides. The coupler has an input for the signal and has first and second outputs. The first waveguide has a first optical connection to the first output, and the second waveguide has a second optical connection to the second output. Both waveguides have the same propagation length. The first and second waveguides include different widths at the respective optical connections to the respective outputs. This coupler can be used with another input couplers, two additional waveguides, and two 2×2 output couplers to provide a 90-degree hybrid for mixing signal light and local oscillator light in a coherent receiver or the like.

A waveguide mode filter. In some embodiments, the waveguide mode filter includes a first section of waveguide. The first section may have: a first end; a second end; a rate of change of curvature having a magnitude not exceeding 15/mm.sup.2 within the first section; a curvature having a magnitude of at most 0.03/mm at the first end; and a curvature having a magnitude of at least 0.1/mm at the second end.

A photonic integrated circuit. In some embodiments, the photonic integrated circuit includes: a waveguide; and a waveguide facet, a first end of the waveguide being at the waveguide facet, a first angle being an angle between: the waveguide at the first end of the waveguide and the normal to the waveguide facet, the first angle being at least 5 degrees, a first section of the waveguide having a first end at the waveguide facet and a second end, the first section having: a curvature of less than 0.01/mm at the first end of the first section, a curvature of less than 0.01/mm at the second end of the first section, and a curvature of at least 0.1/mm at a point between the first end and the second end.

A multi-level semiconductor device, the device including: a first level including integrated circuits; a second level including a structure designed to conduct electromagnetic waves, where the second level is disposed above the first level, where the first level includes crystalline silicon; and an oxide layer disposed between the first level and the second level, where the second level is bonded to the oxide layer, and where the bonded includes oxide to oxide bonds.

Structures for a waveguide bend and methods of fabricating a structure for a waveguide bend. A waveguide core has a first section, a second section, and a waveguide bend connecting the first section with the second section. The waveguide core includes a first side surface extending about an inner radius of the waveguide bend and a second side surface extending about an outer radius of the waveguide bend. A curved strip is arranged over the waveguide bend adjacent to the first side surface or the second side surface.

An optical circuit for routing a signal includes a coupler and first and second waveguides. The coupler has an input for the signal and has first and second outputs. The first waveguide has a first optical connection to the first output, and the second waveguide has a second optical connection to the second output. Both waveguides have the same propagation length. The first and second waveguides include different widths at the respective optical connections to the respective outputs. This coupler can be used with another input couplers, two additional waveguides, and two 2×2 output couplers to provide a 90-degree hybrid for mixing signal light and local oscillator light in a coherent receiver or the like.

Various polarization rotator splitter (PRS) configurations are disclosed. In an example embodiment, a system includes a PRS that includes a silicon nitride (SiN) rib waveguide core that includes a rib and a ridge that extends vertically above the rib, the SiN rib waveguide core having a total height h.sub.SiN from a bottom of the rib to a top of the ridge, a rib height h.sub.rib from the bottom of the rib to a top of the rib, a rib width w.sub.rib, and a top width w.sub.SiN of the ridge. The rib width w.sub.rib varies along at least a portion of a length of the SiN rib waveguide core.