Embodiments herein relate to photonic integrated circuits with an on-chip optical isolator. A photonic transmitter chip may include a laser and an on-chip isolator optically coupled with the laser that includes an optical waveguide having a section coupled with a magneto-optic liquid phase epitaxy grown garnet film. In some embodiments, a cladding may be coupled with the garnet film, the on-chip isolator may be arranged in a Mach-Zehnder interferometer configuration, the waveguide may include one or more polarization rotators, and/or the garnet film may be formed of a material from a rare-earth garnet family. Other embodiments may be described and/or claimed.

An optoelectronic device includes a substrate, having a recess formed therein. An optical isolator is mounted in the recess. A laser includes a stack of epitaxial layers on the substrate and emits a beam of radiation toward the recess along a direction parallel to a surface of the substrate. A waveguide directs the beam emitted by the laser into the optical isolator.

A method and system for coupling optical signals into silicon optoelectronic chips are disclosed and may include coupling one or more optical signals into a back surface of a CMOS photonic chip comprising photonic, electronic, and optoelectronic devices. The devices may be integrated in a front surface of the chip and one or more optical couplers may receive the optical signals in the front surface of the chip. The optical signals may be coupled into the back surface of the chip via one or more optical fibers and/or optical source assemblies. The optical signals may be coupled to the grating couplers via a light path etched in the chip, which may be refilled with silicon dioxide. The chip may be flip-chip bonded to a packaging substrate. Optical signals may be reflected back to the grating couplers via metal reflectors, which may be integrated in dielectric layers on the chip.

A light shield may be formed in photonic integrated circuit between integrated optical devices of the photonic integrated circuit. The light shield may be built by using materials already present in the photonic integrated circuit, for example the light shield may include metal walls and doped semiconductor regions. Light-emitting or light-sensitive integrated optical devices or modules of a photonic integrated circuit may be constructed with light shields integrally built in.

An example system includes a grating coupled laser, a laser optical interposer (LOI), an optical isolator, and a light redirector. The grating coupled laser includes a laser cavity and a transmit grating optically coupled to the laser cavity. The transmit grating is configured to diffract light emitted by the laser cavity out of the grating coupled laser. The LOI includes an LOI waveguide with an input end and an output end. The optical isolator is positioned between the surface coupled edge emitting laser and the LOI. The light redirector is positioned to redirect the light, after the light passes through the optical isolator, into the LOI waveguide of the LOI.

A nonreciprocal waveguide includes a substrate, a light propagation path, a magnetic member, an insulating layer, and a mask. The light propagation path is positioned at the substrate along a substrate surface. The magnetic member is positioned at the substrate along part of the light propagation path in a longitudinal direction. The insulating layer is positioned at the substrate and contains the light propagation path and the magnetic member. Inside the insulating layer, the mask is positioned further away than the light propagation path from the substrate. As seen from a direction perpendicular to the substrate surface, the mask overlaps at least part of the light propagation path in a width direction from a side of the light propagation path opposite to the magnetic member in the width direction. The mask is positioned in at least a range in which the magnetic member is positioned in the longitudinal direction.

In an example, a photonic system includes a Si PIC with a Si substrate, a SiO.sub.2 box formed on the Si substrate, a first layer, and a second layer. The first layer is formed above the SiO.sub.2 box and includes a SiN waveguide with a coupler portion at a first end and a tapered end opposite the first end. The second layer is formed above the SiO.sub.2 box and vertically displaced above or below the first layer. The second layer includes a Si waveguide with a tapered end aligned in two orthogonal directions with the coupler portion of the SiN waveguide such that the tapered end of the Si waveguide overlaps in the two orthogonal directions and is parallel to the coupler portion of the SiN waveguide. The tapered end of the SiN waveguide is configured to be adiabatically coupled to a coupler portion of an interposer waveguide.

An example system includes a grating coupled laser, a laser optical interposer (LOI), an optical isolator, and a light redirector. The grating coupled laser includes a laser cavity and a transmit grating optically coupled to the laser cavity. The transmit grating is configured to diffract light emitted by the laser cavity out of the grating coupled laser. The LOI includes an LOI waveguide with an input end and an output end. The optical isolator is positioned between the surface coupled edge emitting laser and the LOI. The light redirector is positioned to redirect the light, after the light passes through the optical isolator, into the LOI waveguide of the LOI.

A method and system for coupling optical signals into silicon optoelectronic chips are disclosed and may include coupling one or more optical signals into a back surface of a CMOS photonic chip comprising photonic, electronic, and optoelectronic devices. The devices may be integrated in a front surface of the chip and one or more optical couplers may receive the optical signals in the front surface of the chip. The optical signals may be coupled into the back surface of the chip via one or more optical fibers and/or optical source assemblies. The optical signals may be coupled to the grating couplers via a light path etched in the chip, which may be refilled with silicon dioxide. The chip may be flip-chip bonded to a packaging substrate. Optical signals may be reflected back to the grating couplers via metal reflectors, which may be integrated in dielectric layers on the chip.

A light shield may be formed in photonic integrated circuit between integrated optical devices of the photonic integrated circuit. The light shield may be built by using materials already present in the photonic integrated circuit, for example the light shield may include metal walls and doped semiconductor regions. Light-emitting or light-sensitive integrated optical devices or modules of a photonic integrated circuit may be constructed with light shields integrally built in.