Structures including an edge coupler and methods of fabricating a structure including an edge coupler. The structure includes a dielectric layer including an edge, a waveguide core region on the dielectric layer, and multiple segments on the dielectric layer. The waveguide core region has an end surface, and the waveguide core region is lengthwise tapered toward the end surface. The segments are positioned between the waveguide core region and the edge of the dielectric layer. A waveguide core has a section positioned over the waveguide core region in an overlapping arrangement. The waveguide core has an end surface, and the section of the waveguide core is lengthwise tapered toward the end surface.

Embodiments described herein provide for methods of forming optical device structures having continuously increasing or decreasing duty cycles. One embodiment includes a device. The device includes a plurality of optical device structures. Each optical device structure of the plurality of optical device structures includes a plurality of discrete zones. Each discrete zone of the plurality of discrete zones has a critical dimension. The device further includes a plurality of transition zones disposed between two discrete zones of the plurality of discrete zones. The critical dimension of each transition zone of the plurality of transition zones continuously increases or decreases across a length of each optical device structure of the plurality of optical device structures.

Embodiments described herein provide for methods of forming optical device structures having continuously increasing or decreasing duty cycles. One embodiment includes a device. The device includes a plurality of optical device structures. Each optical device structure of the plurality of optical device structures includes a plurality of discrete zones. Each discrete zone of the plurality of discrete zones has a critical dimension. The device further includes a plurality of transition zones disposed between two discrete zones of the plurality of discrete zones. The critical dimension of each transition zone of the plurality of transition zones continuously increases or decreases across a length of each optical device structure of the plurality of optical device structures.

The present disclosure generally pertains to systems and methods that utilize optical frequency discriminators based on fiber Bragg gratings. In some embodiments, an optical frequency discriminator has a polarization-maintaining fiber Bragg grating (PM-FBG), and an incoming polarized optical signal is reflected from the PM-FBG, which differentiates the two polarization modes in the incoming signal according its frequency relative to the two resonance peaks of the PM-FBG. The optical frequency discriminator then compares (e.g., subtracts) the reflected power in the two polarization modes to provide an output having an amplitude that varies linearly with the frequency of the incoming signal. This output may then be used to extract various information about the frequency of the incoming signal. As an example, the output may be used to recover data that has been frequency modulated onto the incoming signal or to characterize the frequency noise of the incoming signal.

The present disclosure generally pertains to systems and methods that utilize optical frequency discriminators based on fiber Bragg gratings. In some embodiments, an optical frequency discriminator has a polarization-maintaining fiber Bragg grating (PM-FBG), and an incoming polarized optical signal is reflected from the PM-FBG, which differentiates the two polarization modes in the incoming signal according its frequency relative to the two resonance peaks of the PM-FBG. The optical frequency discriminator then compares (e.g., subtracts) the reflected power in the two polarization modes to provide an output having an amplitude that varies linearly with the frequency of the incoming signal. This output may then be used to extract various information about the frequency of the incoming signal. As an example, the output may be used to recover data that has been frequency modulated onto the incoming signal or to characterize the frequency noise of the incoming signal.

An apparatus includes a fiber-optic connector configured to be connected between one or more optical fibers having a plurality of fiber cores and a photonic integrated circuit including a plurality of vertical-coupling elements disposed along a main surface of the photonic integrated circuit. The fiber-optic connector includes a polarization beam splitter and a patterned birefringent plate. The polarization beam splitter is configured to split an incident light beam from a corresponding fiber core into a first beam having a first polarization and a second beam having a second polarization different from the first polarization. The patterned birefringent plate includes a first region and a second region, the first region has a first optical birefringence, the second region has a second optical birefringence that is different from the first optical birefringence. The difference in the first and second optical birefringence is caused by performing at least one of (i) applying localized heating to the first region without applying localized heating to the second region to cause the first region to have a lower birefringence as compared to the second region, or (ii) applying different amounts of localized heating to the first and second regions to cause the first region to have a first birefringence and the second region to have a second birefringence different from the first birefringence.

An optical structure may be provided by forming a silicon grating structure over a dielectric material layer, depositing at least one dielectric material layer over the silicon grating structure, and depositing at least one dielectric etch stop layer over the at least one dielectric material layer. The at least one dielectric etch stop layer includes at least one dielectric material selected from silicon nitride and silicon oxynitride. A passivation dielectric layer may be formed over the at least one dielectric etch stop layer, and a patterned etch mask layer may be formed over the passivation dielectric layer. An opening may be formed through an unmasked portion of the passivation dielectric layer by performing an anisotropic etch process that etches the dielectric material selective to a silicon nitride or silicon oxynitride using the patterned etch mask layer as a masking structure. The at least one etch mask layer minimizes overetching.

An optical device for coupling light propagating between a waveguide and an optical transmission component is provided. The optical device includes a taper portion and a grating portion. The taper portion is disposed between the grating portion and the waveguide. The grating portion includes rows of grating patterns. A first size of a first grating pattern in a first row of grating patterns is larger than a second size of a second grating pattern in a second row of grating patterns. A first distance between the first row of grating patterns and the waveguide is less than a second distance between the second row of grating patterns and the waveguide.

An optical device for coupling light propagating between a waveguide and an optical transmission component is provided. The optical device includes a taper portion and a grating portion. The taper portion is disposed between the grating portion and the waveguide. The grating portion includes rows of grating patterns. A first size of a first grating pattern in a first row of grating patterns is larger than a second size of a second grating pattern in a second row of grating patterns. A first distance between the first row of grating patterns and the waveguide is less than a second distance between the second row of grating patterns and the waveguide.

Embodiments of the disclosure provide an optical antenna for a photonic integrated circuit (PIC). The optical antenna includes a semiconductor waveguide on a semiconductor layer. The semiconductor waveguide includes a first vertical sidewall over the semiconductor layer over the semiconductor layer. A plurality of grating protrusions extends horizontally from the first vertical sidewall of the semiconductor waveguide.