Positioned between first and second planes of a volume are one or more optical elements. Light-impeding structures absorb light, reflect light, or both. Each light-impeding structure in a first set: intersects the first (and second) plane with a first (and second) cross-sectional shape, comprises a first (and second) maximum cross-sectional length equal to the length of the longest line between two maximally separated points of the first (and second) cross-sectional shape, and is separated from nearest neighboring light-impeding structures in the first set by a distance no larger than four times the length of the first maximum cross-sectional length or four times the length of the second maximum cross-sectional length. Light propagation through one or more points is impeded, such that any line that intersects at least one of the points, is entirely within the volume, and traverses through the first set, intersects at least one light-impeding structure.

An optical attenuator and/or optical terminator is provided. The device includes an optical channel having two regions with different optical properties, such as an undoped silicon region which is less optically absorptive and a doped silicon region which is more optically absorptive. Other materials may also be used. A facet at the interface between the two regions is oriented at a non-perpendicular angle relative to a longitudinal axis of the channel. The angle can be configured to mitigate back reflection. Multiple facets may be included between different pairs of regions. The device may further include curved and/or tapers to further facilitate attenuation and/or optical termination.

A photonic integrated circuit (PIC) may be optically aligned to a plurality of optical components (e.g., an optical fiber array). Optical alignment may be facilitated by the use of an optical impedance element coupled between a first input/output (I/O) optical waveguide and a second I/O optical waveguide of the PIC. The optical impedance element me be configured to be transmissive during optical alignment and to be non-transmissive during the regular operation of the PIC.

A laser assembly of the present invention includes a plurality of laser element bases in which laser elements are installed on main surfaces, an optical waveguiding substrate in which an optical waveguiding layer is provided on a main surface, a plurality of spacer layers which are disposed away from each other at positions corresponding to the bases on a bonding surface of the substrate, and a plurality of metal laminate films which bond bonding surfaces of the plurality of laser element bases and the bonding surface of the optical waveguiding substrate. The plurality of metal laminate films are respectively disposed on the plurality of spacer layers and have a plurality of first metal films and second metal films that are disposed on the bonding surfaces of the plurality of laser element bases and made of metals capable of being eutectic with metals constituting the first metal films.

A nonreciprocal Solar thermophotovoltaic (STPV) system includes an absorber configured to absorb broad-spectrum solar radiation and generate heat an intermediate emitter, and a single-junction photovoltaic cell configured to convert solar radiation to electrical energy. The intermediate emitter includes nonreciprocal radiative properties. The nonreciprocal radiative properties include absorbing light from the front side but only emitting light to the backside.

A waveguide structure (100) for a photonic integrated circuit, comprising: a substrate; an active region (102) comprising a diode junction, the active region comprising: a light emission portion (102a) to emit light in a first direction and a second direction perpendicular the first direction; and a light absorption portion (102b) to absorb light emitted from the light emission portion (102a) in the second direction; a first contact corresponding to the light emission portion (102a); and a second contact corresponding to the light absorption portion (102b).

The disclosure relates to a PIC structure including a photonic component on a semiconductor substrate. A passive optical guard is composed of a light absorbing material and is in proximity to the photonic component. The passive optical guard includes at least a portion in an active semiconductor layer of the semiconductor substrate and may be entirely below a first metal layer. The passive optical guard may include at least one of: a germanium body positioned at least partially in a silicon element in the active semiconductor layer, a silicon body having a high dopant concentration in the active semiconductor layer, and a polysilicon body having a high dopant concentration over the silicon body.

A carrier-modulated waveguide structure which comprises a semiconductor bias unit, a light absorbing component, and a transporting control element is provided. The light absorbing component is disposed over a part of the semiconductor bias unit and the transporting control element is arranged at one side of both the semiconductor bias unit and the light absorbing component and connected with the side of the light absorbing component. The transporting control element comprises a main body. One side of the main body is connected with the light absorbing component and another side of the main body is provided with a plurality of carrier channels spaced apart from one another. The plurality of carrier channels is connected with a plurality of light sensors correspondingly. Thereby difference in detection probability and dead period of single photon avalanche diodes can be overcome by the carrier channels conducted due to electrical field for photon detection.

A photonic integrated circuit (PIC) includes a waveguide in or over a semiconductor substrate. The waveguide has a terminal end. The PIC also includes an optical absorber having a curved shape adjacent to opposing sides and an endwall of the terminal end of the waveguide, i.e., it surrounds the terminal end of the waveguide. The optical absorber is multi-layered and includes a light absorbing layer. The light absorbing layer may include germanium or a vanadate. The optical absorber terminates or attenuates any stray optical signals from the waveguide while maintaining low back reflection.

An optical chip includes: an optical port, coupled to a fiber and configured to receive a first optical signal from the fiber, where the first optical signal includes a component in a transverse magnetic TM mode; a polarization splitter and rotator PSR, configured to perform first processing on the first optical signal to generate a second optical signal, where the second optical signal is in a transverse electric TE mode, and the second optical signal is a single-channel multi-wavelength optical signal; at least one wavelength demultiplexer DeMux, configured to perform second processing on the second optical signal to generate a third optical signal, where the third optical signal is a multi-channel single-wavelength optical signal; and a photodetector array, configured to convert the third optical signal into an electrical signal. The optical port, the PSR, and the at least one DeMux are made of silicon nitride SiN.