Methods and systems for selectively illuminated integrated photodetectors with configured launching and adaptive junction profile for bandwidth improvement may include a photonic chip comprising an input waveguide and a photodiode. The photodiode comprises an absorbing region with a p-doped region on a first side of the absorbing region and an n-doped region on a second side of the absorbing region. An optical signal is received in the absorbing region via the input waveguide, which is offset to one side of a center axis of the absorbing region; an electrical signal is generated based on the received optical signal. The first side of the absorbing region may be p-doped. P-doped and n-doped regions may alternate on the first and second sides of the absorbing region along the length of the photodiode. The absorbing region may comprise germanium, silicon, silicon/germanium, or similar material that absorbs light of a desired wavelength.

In a waveguide device, unnecessary optical power is appropriately terminated. According to an embodiment of the present invention, the waveguide device has a termination structure filled with a light blocking material to terminate light from a waveguide end. In the termination structure, a cladding and a core are removed to form a groove on an optical waveguide. The groove is filled with a material (light blocking material) that attenuates the intensity of light. Thus, light input to the termination structure is attenuated by the light blocking material, suppressing crosstalk which possibly effects on other optical devices. Thus, such a termination structure can restrain crosstalk occurred in optical devices integrated in the same substrate and can also suppress crosstalk which possibly effects on any other optical device connected directly to the substrate.

Provided is a light absorber. The light absorber includes a reflective layer having conductivity, a conductive pattern disposed on the reflective layer and including at least one first opening, a nano-antenna disposed on the reflective layer and vertically overlapping the first opening, and an insulating pattern interposed between the reflective layer and the conductive pattern and between the reflective layer and the nano-antenna. The reflective layer, the conductive pattern, and the nano-antenna are electrically insulated from each other.

A self-fit optical filter includes a dual fiber collimator, a diffraction grating for spatially dispersing the input light beam into a plurality of sub-beams, a cylindrical lens for focusing each of the sub-beams at a saturable absorber which becomes saturated dependent on intensity of light, and a reflector for reflecting the sub-beams back along their optical paths. A method of filtering includes: demultiplexing an input beam into a plurality of sub-beams having distinct center wavelengths, at least partially absorbing one or more of the sub-beams by using a saturable absorber while allowing other sub-beams to pass through, substantially unattenuated, and multiplexing the sub-beams into an output optical signal.

Some implementations described herein include a photonics integrated circuit device including a photonics structure. The photonics structure includes a waveguide structure and an optical attenuator structure. In some implementation, the optical attenuator structure is formed on an end region of the waveguide structure and includes a metal material or a doped material. In some implementations, the optical attenuator structure includes a gaussian doping profile within a portion of the waveguide structure. The optical attenuator structure may absorb electromagnetic waves at the end of the waveguide structure with an efficiency that is improved relative to a spiral optical attenuator structure or metal cap optical attenuator structure.

A diffraction grating pattern is formed in the first insulating film on the active layer by electron beam lithography, and at the same time an end facet formation pattern whose end portion corresponds to a position of an emission end facet of the optical modulator is formed in the first insulating film on the optical absorption layer by electron beam lithography. A second insulating film is formed on the end facet formation pattern. The diffraction grating formation layer is etched using the first and second insulating films as masks to form a diffraction grating, and is embedded with an embedded layer. The second insulating film is removed. A third insulating film is formed on the diffraction grating and the embedded layer not to cover the end facet formation pattern. The optical absorption layer is etched using the first and third insulating films as masks to form the emission end facet.

Some implementations described herein include a photonics integrated circuit device including a photonics structure. The photonics structure includes a waveguide structure and an optical attenuator structure. In some implementation, the optical attenuator structure is formed on an end region of the waveguide structure and includes a metal material or a doped material. In some implementations, the optical attenuator structure includes a gaussian doping profile within a portion of the waveguide structure. The optical attenuator structure may absorb electromagnetic waves at the end of the waveguide structure with an efficiency that is improved relative to a spiral optical attenuator structure or metal cap optical attenuator structure.

In a semiconductor device, first dummy patterns including a different material from transmission lines (first optical waveguide and second optical waveguide) are formed in a first region close to the transmission lines, and second dummy patterns, which include the same material as the transmission lines and do not function as the transmission lines, are formed in a second region apart from the transmission lines.

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 device includes an optical isolator disposed between adjacent optical waveguides along a direction. The optical isolator has vertical or horizontal dimensions that are different than at least one of the optical waveguides. The vertical and horizontal dimensions are greater than vertical and horizontal dimensions of at least one of the waveguides. In various embodiments, the structure of the optical isolator can be a planar structure, a columnar periodic structure, or a grating structure. The material of the optical isolator can be a metallic material or a dielectric material. In some embodiments, the optical isolator and the optical waveguides are used to enhance the performance of an optical multiplexing device.