Described are various configurations of optical structures having asymmetric-width waveguides. A photodetector can include parallel waveguides that have different widths, which can be connected via passive waveguide. One or more light absorbing regions can be proximate to the waveguides to absorb light propagating through one or more of the parallel waveguides. Multiple photodetectors having asymmetric width waveguides can operate to transduce light in different modes in a polarization diversity optical receiver.

A light receiving device includes, on a substrate, a Si waveguide core provided in a dielectric layer, a first i-type waveguide clad, an i-type core layer, a second i-type waveguide clad, p-type layers disposed on one side of a side surface of a layered structure in a light waveguide direction, the layered structure including the first i-type waveguide clad, the i-type core layer, and the second i-type waveguide clad, n-type layers disposed on the other side, and an electrode on a surface of each of the n-type layers. A width of the Si waveguide core is set to be able to suppress absorption of light in a vicinity of an input edge of the i-type core layer.

A light sensor includes a semiconductor substrate supporting a number of pixels. Each pixel includes a photoconversion zone extending in the substrate between a front face and a back face of the substrate. An optical diffraction grating is arranged over the back face of the substrate at a position facing the photoconversion zone of the pixel. For at least two different pixels of the light sensor, the optical diffraction gratings have different pitches. Additionally, the optical grating of each pixel is surrounded by an opaque wall configured to absorb at operating wavelengths of the sensor.

An imaging device may include single-photon avalanche diodes (SPADs). To improve the sensitivity and signal-to-noise ratio of the SPADs, light scattering structures may be formed in the semiconductor substrate to increase the path length of incident light through the semiconductor substrate. To mitigate crosstalk, an isolation structure may be formed in a ring around the SPAD. The isolation structure may be a hybrid isolation structure with both a metal filler that absorbs light and a low-index filler that reflects light. The isolation structure may be formed as a single trench or may include a backside deep trench isolation portion and a front side deep trench isolation portion. The isolation structure may also include a color filtering material.

Techniques for enhancing the absorption of photons in semiconductors with the use of microstructures are described. The microstructures, such as pillars and/or holes, effectively increase the effective absorption length resulting in a greater absorption of the photons. Using microstructures for absorption enhancement for silicon photodiodes and silicon avalanche photodiodes can result in bandwidths in excess of 10 Gb/s at photons with wavelengths of 850 nm, and with quantum efficiencies of approximately 90% or more.

An apparatus for light detection includes a light, or photon, detector assembly and a dielectric resonator layer coupled to the detector assembly. The dielectric resonator layer is configured to receive transmission of incident light that is directed into the detector assembly by the dielectric resonator layer. The dielectric resonator layer resonates with a range of wavelengths of the incident light.

An infrared detector includes: a first light receiving layer having a first cutoff wavelength; a second light receiving layer having a second cutoff wavelength longer than the first cutoff wavelength; an intermediate filter layer having a third cutoff wavelength that is the same as or longer than the first cutoff wavelength and the same as or shorter than the second cutoff wavelength, the intermediate filter layer being disposed between the first light receiving layer and the second light receiving layer; a first barrier layer disposed between the first light receiving layer and the intermediate filter layer; and a second barrier layer disposed between the second light receiving layer and the intermediate filter layer.

A large single-photon avalanche diode (SPAD) array is integrated with optical waveguide (WG) based devices. SPAD is a very sensitive optical detector fabricated on a semiconductor chip and WG structures are also built into the same chip. WG structures are configured to accumulate SPAD detection current. Together, they form an ultra-sensitive optical detector with high-speed response and a large aperture.

An optical waveguide type photodetector includes a first semiconductor layer of a first conductive type, a multiplication layer of a first conductive type on the first semiconductor layer, an optical waveguide structure, and a photodiode structure. The photodiode structure has a third semiconductor layer of a second conductive type, an optical absorption layer of an intrinsic conductive type or of a second conductive type, and a second semiconductor layer of a second conductive type. The optical waveguide structure includes an optical waveguiding core layer and a cladding layer. An end face of the photodiode structure located in a second region of the first semiconductor layer and an end face of the optical waveguide structure located in a first region of the first semiconductor layer are in contact.

Disclosed are infrared (IR) light detectors. The detectors operate by generating hot electrons in a metallic absorber layer on photon absorption, the electrons being transported through an energy barrier of an insulating layer to a metal or semiconductor conductive layer. The energy barrier is set to bar response to wavelengths longer than a maximum wavelength. Particular embodiments also have a pattern of metallic shapes above the metallic absorber layer that act to increase photon absorption while reflecting photons of short wavelengths; these particular embodiments have a band-pass response.