A grating coupler couples a waveguide to a beam and is formed of patterned shapes in a first and second layer of planar material, the shapes embedded in background material, the layers separated by less than one wavelength. The shapes are organized as a plurality of adjacent unit cells arranged along a direction of propagation of light with each unit cell including a shape of the first material and a shape of the second material, each unit cell having design parameters including a period, a width wb of the shape of first planar material, a width wt of the shape of second planar material, and an offset between the shapes. The coupler has a directivity ratio D is at least 10 dB between “up” and “down” radiation; and unit cells differ in at least one parameter selected from period, wb, wt, and offset to provide a predetermined beam shape.

A grating coupler couples a waveguide to a beam and is formed of patterned shapes in a first and second layer of planar material, the shapes embedded in background material, the layers separated by less than one wavelength. The shapes are organized as a plurality of adjacent unit cells arranged along a direction of propagation of light with each unit cell including a shape of the first material and a shape of the second material, each unit cell having design parameters including a period, a width wb of the shape of first planar material, a width wt of the shape of second planar material, and an offset between the shapes. The coupler has a directivity ratio D is at least 10 dB between “up” and “down” radiation; and unit cells differ in at least one parameter selected from period, wb, wt, and offset to provide a predetermined beam shape.

A light flux diameter expanding element includes a light guiding plate with a light input face and a light output face, and with a thickness of 0.2 mm to 0.8 mm; a diffraction grating on the input side; and a diffraction grating on the output side, and is provided so as to have the same grating period as that of the diffraction grating on the input side, in which a forming region of the diffraction grating on the input side is smaller than that of the output side, and a grating period of the diffraction grating on the input side is a period in which a small diffraction angle in diffraction angles of +1-st order diffracted light and −1-st order diffracted light, which are diffracted in the diffraction grating on the input side, in the light guiding plate becomes larger than a critical angle of the light guiding plate.

A light flux diameter expanding element includes a light guiding plate with a light input face and a light output face, and with a thickness of 0.2 mm to 0.8 mm; a diffraction grating on the input side; and a diffraction grating on the output side, and is provided so as to have the same grating period as that of the diffraction grating on the input side, in which a forming region of the diffraction grating on the input side is smaller than that of the output side, and a grating period of the diffraction grating on the input side is a period in which a small diffraction angle in diffraction angles of +1-st order diffracted light and −1-st order diffracted light, which are diffracted in the diffraction grating on the input side, in the light guiding plate becomes larger than a critical angle of the light guiding plate.

Aspects described herein include an optical apparatus comprising a multiple-stage arrangement of two-mode Bragg gratings comprising: at least a first Bragg grating of a first stage. The first Bragg grating is configured to transmit a first two wavelengths and to reflect a second two wavelengths of a received optical signal. The optical apparatus further comprises a second Bragg grating of a second stage. The second Bragg grating is configured to transmit one of the first two wavelengths and to reflect an other of the first two wavelengths. The optical apparatus further comprises a third Bragg grating of the second stage. The third Bragg grating is configured to transmit one of the second two wavelengths and to reflect an other of the second two wavelengths.

An isolator includes a first waveguide and a second waveguide on a substrate having a substrate surface, the first waveguide and the second waveguide located along the substrate surface and overlapping each other as viewed from the substrate. The first waveguide and the second waveguide each include a core and a clad. The core has a first surface facing the substrate surface, and a second surface opposite to the first surface. The clad contacts the first surface and the second surface of the core. The first waveguide has a first end and a second end, and has a port for input and output of electromagnetic waves at each of the first end and the second end. The core of the second waveguide includes a non-reciprocal member in at least one part of a cross section intersecting a direction in which the second waveguide extends.

Disclosed is a system and method for communication using an efficient fiber-to-chip grating coupler with a high coupling efficiency. In one embodiment, a method for communication, includes: transmitting optical signals between a semiconductor photonic die on a substrate and an optical fiber array attached to the substrate using at least one corresponding grating coupler on the semiconductor photonic die, wherein the at least one grating coupler each comprises a plurality of coupling gratings, a waveguide, a cladding layer, a first reflection layer and a second reflection layer, wherein the plurality of coupling gratings each comprises at least one step in a first lateral direction and extends in a second lateral direction, wherein the first and second lateral directions are parallel to a surface of the substrate and perpendicular to each other in a grating plane, wherein the first reflection layers are configured such that the plurality of coupling gratings is disposed between the first reflection layer and the cladding layer, wherein the second reflection layer are configured such that the cladding layer is disposed between the second reflection layer and the waveguide.

Systems and embodiments for an integrated photonics mode splitter and converter are provided herein. In certain embodiments, a system includes a substrate having a first index of refraction. Additionally, the system includes a waveguide layer on the substrate, wherein the waveguide has a second index of refraction different from the first index of refraction. Also, the waveguide layer includes one or more mode splitters that receive at least one of a first photon in a first mode and a second photon in a second mode through an input port and provide one of the first photon through a first output port and the second photon through a second output port. The waveguide layer also includes a mode converter coupled to the second output of a mode splitter, wherein the mode converter receives the second photon through a port and outputs the second photon in the first mode through the port.

When routing light on photonic integrated circuit (PIC) chips optical back-reflection and scattering can be highly detrimental to the desired application. Unused ports of optical devices, such as MMI, DC, Y-junction, PD, etc. are a cause for back-reflection and scattering, whereby the scattered light could get picked up by adjacent components, e.g. photodetectors. Management of stray light on the PIC is needed to prevent the undesired coupling between various components and to reduce noise. A dump taper may be used to guide and scatter stray light away from sensitive components or fully absorb the light while maintaining very low reflection from the taper. A doped dump taper may be used to passively absorb light reaching the unused port, thereby eliminating unwanted reflection and scattering. Alternatively, an undoped taper may be used to scatter light away from sensitive components while maintaining very low back-reflection.

A biosensing system includes a biosensor, a light source, first and second photodetectors, and a calculator. The light source is disposed to irradiate the biosensor, so as to generate two or more of a coupled light beam, a reflected light beam, a transmitted light beam and a diffracted light beam. The first photodetector is disposed to measure an intensity of one of the generated light beams that is indicative of an effect of an analyte on light to obtain a first intensity value. The second photodetector is disposed to measure an intensity of another one of the generated light beams that is indicative of an effect of the analyte on light to obtain a second intensity value. The calculator performs compensation calculation based at least on the first and second intensity values.