This application provides an example light source switching apparatus. The apparatus includes first and second multi-mode interference (MMI) couplers, and a phase modulator. The first MMI coupler includes four ports, where first and second ports are located on one side, and third and fourth ports are located on the other side. The second MMI coupler includes three ports, where fifth and sixth ports are located on one side, and a seventh port is located on the other side. The first and the second ports connect to the fifth and the sixth ports, respectively, to form two connections. The phase modulator is disposed on one of the two connections, and the seventh port connects to an optical modulator. Both the third and the fourth ports connect to a light source emitting continuous light, and the phase modulator selects one of the two light sources for output from the seventh port.

In some embodiments, the present disclosure relates to a modulator device that includes an input terminal configured to receive impingent light. A first waveguide has a first output region and a first input region that is coupled to the input terminal. A second waveguide is optically coupled to the first waveguide and has second input region and a second output region that is coupled to the input terminal. An output terminal coupled to the first output region of the first waveguide and the second output region of the second waveguide is configured to provide outgoing light that is modulated. A heater structure is configured to provide heat to the first waveguide to induce a temperature difference between the first and second waveguides. A gas-filled isolation structure is proximate to the heater structure and is configured to thermally isolate the second waveguide from the heat provided to the first waveguide.

An optical demultiplexer is disclosed that separates light including a plurality of wavelengths into light of respective wavelengths. Unit circuits are cascaded in a tree structure. In optical demultiplexer components having the same structure, a combination of arm length differences in waveguide pairs is the same with respect to the N−1 Asymmetric Mach-Zehnder interferometers in which the phase shifters are arranged, where N equals number of 2×2 couplers. In three of the optical demultiplexer components in at least one of the unit circuits, N is three or more. Each of control circuits controls the phase shifters arranged in a corresponding optical demultiplexer component of a corresponding unit circuit in order to increase or decrease a value of a function having, as an argument, a power value acquired by a monitor from among monitors arranged at four optical waveguides at an output side of the corresponding unit circuit.

The invention relates to an optical waveguide-type optical multiplexer, an optical waveguide-type multiplexing light source device and an image projection device, where the intensity of a light beam emitted from a light source is attenuated to a desired value without installing an additional optical attenuator element. One of a plurality of optical waveguides on the light emission side for emitting light distributed/multiplexed in an optical multiplexer unit excluding an optical waveguide on the light emission side in which the greatest output light power can be gained for each wavelength from among the optical waveguides on the light emission side in the case where a plurality of light sources is driven is used as an optical waveguide for light emission.

The application provides a interface light path structure with all polarization-maintaining function. A first polarization-maintaining-transferring device includes a first port, a second port, and a third port, wherein the first port receives a first polarized light output by the polarization beam-splitting device, the second port is connected to the first Faraday rotation mirror, and the third port is connected to a first port of the first polarization-maintaining coupler. A second polarization-maintaining-transferring device includes a first port, a second port, and a third port, wherein the first port receives a second polarized light output by the polarization beam-splitting device, the second port is connected to the second Faraday rotation mirror, and the third port is connected to a second port of the first polarization-maintaining coupler.

An optical waveguide interferometer that includes a first optical section, a second optical section, and a set of optical waveguides configured to connect the first and second optical sections, such that light propagating between the first optical section and the second optical section passes through each optical waveguide in the set, wherein the set of optical waveguides includes a first optical waveguide having a first length and a first width and a second optical waveguide having a second length and a second width, wherein the second length is greater than the first length, and the second width is greater than the first width.

A photonic integrated circuit (PIC) for determining a wavelength of an input signal is disclosed. The PIC comprises: a substrate; a first Mach-Zehnder Interferometer (MZI) disposed over the substrate, comprising first optical waveguides having a first optical path length difference, and configured to receive a first output optical signal from a light source. The PIC also comprises a second Mach-Zehnder Interferometer (MZI) disposed over the substrate, comprising second optical waveguides having a second optical path length difference, which is greater than the first optical path length difference, and configured to receive a second output optical signal from the light source.

A photonic integrated circuit (PIC) with embedded optical temperature sensing includes an optical interferometer containing a first arm and a second arm, and one or more optical waveguide sections configured to measure an internal temperature of the PIC. The one or more optical waveguide sections are implemented as one or more sections of the first arm and the second arm. The first arm and the second arm have a first optical path length (OPL) and a second OPL and are made of a first material and a second material, respectively.

A device includes a first directional coupler and a second directional coupler. A first arched waveguide forms a first curved optical path between a first output port of the first directional coupler and a first input port of the second directional coupler. The first arched waveguide has an angle of curvature and a radius of curvature. A second arched waveguide has the angle of curvature and the radius of curvature. The first arched waveguide and the second arched waveguide each have a concavity oriented in the same direction. A first straight waveguide is coupled to a second output port of the first directional coupler and a first end of the second arched waveguide. A second straight waveguide is coupled to a second end of the second arched waveguide and a second input port of the second directional coupler.

A device includes a first directional coupler and a second directional coupler. A first arched waveguide forms a first curved optical path between a first output port of the first directional coupler and a first input port of the second directional coupler. The first arched waveguide has an angle of curvature and a radius of curvature. A second arched waveguide has the angle of curvature and the radius of curvature. The first arched waveguide and the second arched waveguide each have a concavity oriented in the same direction. A first straight waveguide is coupled to a second output port of the first directional coupler and a first end of the second arched waveguide. A second straight waveguide is coupled to a second end of the second arched waveguide and a second input port of the second directional coupler.