Methods and devices that provide a variable-bandwidth optical filter with frequency tuning are disclosed. A universal variable bandwidth optical filter architecture is disclosed, based on microring resonators that can vary both operation wavelength and bandwidth with no extra complexity relative to conventional wavelength tunable filters. The filter architecture provides a universal filter design for any arbitrary shape of filter response, such as second-order, fourth-order, sixth-order, and so on. The filter characteristics—insertion loss, in-band ripple, and out-of-band rejection level—may be maintained over the bandwidth tuning range. There is no need for extra heaters to tune the filter's operating bandwidth, as the same heaters used to tune the filter frequency can be used to tune filter bandwidth. The device can be used as an add/drop filter.

Examples herein relate to optical systems. In particular, implementations herein relate to an optical system including an optical transmitter configured to transmit optical signals. The optical transmitter includes a first optical source coupled to an input waveguide and configured to emit light having different wavelengths through the input waveguide. The optical transmitter includes a Mach-Zehnder interferometer that includes a first arm and a second arm. The MZI further includes a first optical coupler configured to couple the emitted light from the input waveguide to the first and second arms and an array of two or more second optical sources coupled to the first arm. Each of the two or more second optical sources are configured to be injection locked to a different respective wavelength of the emitted light transmitted from the first optical source. The MZI further includes a second optical coupler configured to combine the emitted light from the first and second arms after propagating therethrough.

An optical filter system, preferably including an optical input, one or more sets of filters, and/or a control module. A method for optical filter operation, preferably including operating an optical filter system in a normal mode, assessing filter alignment, and/or shifting filter assignments.

An electro-optic receiver includes a polarization splitter and rotator (PSR) that directs incoming light having a first polarization through a first end of an optical waveguide, and that rotates incoming light from a second polarization to the first polarization to create polarization-rotated light that is directed to a second end of the optical waveguide. The incoming light of the first polarization and the polarization-rotated light travel through the optical waveguide in opposite directions. A plurality of ring resonators is optically coupled the optical waveguide. Each ring resonator is configured to operate at a respective resonant wavelength, such that the incoming light of the first polarization having the respective resonant wavelength optically couples into said ring resonator in a first propagation direction, and such that the polarization-rotated light having the respective resonant wavelength optically couples into said ring resonator in a second propagation direction opposite the first propagation direction.

A multi-channel laser source, including: a bus waveguide coupled, at an output end of the bus waveguide, to an output of the multi-channel laser source; a first semiconductor optical amplifier; a first back mirror; a first wavelength-dependent coupler, having a first resonant wavelength, on the bus waveguide; a second semiconductor optical amplifier; a second back mirror; and a second wavelength-dependent coupler, on the bus waveguide, having a second resonant wavelength, different from the first resonant wavelength. In some embodiments the first semiconductor optical amplifier is coupled to the bus waveguide by the first wavelength-dependent coupler, which is nearer to the output end of the bus waveguide than the second wavelength-dependent coupler, the second semiconductor optical amplifier is coupled to the bus waveguide by the second wavelength-dependent coupler, and the first wavelength-dependent coupler is configured to transmit light, at the second resonant wavelength, along the bus waveguide.

An electro-optical chip includes a plurality of transmit macros, each of which includes an optical waveguide and a plurality of ring resonators positioned along the optical waveguide. An optical distribution network is implemented onboard the electro-optical chip and includes a plurality of optical inputs and a plurality of optical outputs. The optical distribution network conveys a portion of light received at a subset of the plurality of optical inputs to one or more of the plurality of optical outputs, such that light conveyed to said one or more of the plurality of optical outputs includes wavelengths of light conveyed to said subset of the plurality of optical inputs. The subset of the plurality of optical inputs includes at least two of the plurality of optical inputs. Each of the plurality of optical outputs is optically connected to the optical waveguide in a corresponding one of the plurality of transmit macros.

An optical element including a plurality of first circuits, the optical element includes a first cascade circuit in which one or more of first circuits are connected in cascade, a second cascade circuit in which one or more of first circuits are connected in cascade, and a combiner circuit configured to connect the first cascade circuit and the second cascade circuit. A first circuit included in the plurality of first circuits includes a first cascade structure in which N (N is an integer of 1 or larger) of 2-input and 2-output phase shifters and (N+1) of 2-input and 2-output couplers are alternately connected in cascade, and a first controller configured to control the N phase shifters in a direction in which optical input power decreases, the first controller being connected to one of two outputs of the first cascade structure.

A method and system for locking the resonance frequency of ring resonators by using laser sources to emit a plurality of different wavelengths, applying a tagging signal to each of the wavelengths, multiplexing the tagged wavelengths using a wavelength division multiplexor, coupling the multiplexed tagged wavelengths onto a bus waveguide, detecting the multiplexed tagged wavelengths with a first photodetector disposed before a first ring resonator and a second photodetector disposed after a last ring resonator of a plurality of ring resonators, sending the signals detected by the first and second photodetector to a processor, which identifies and processes the tagging signals, generating a control signal for each ring resonator, by the processor and applying the control signals to phase shifters on each ring resonator of the plurality of ring resonators to tune and align the resonance wavelengths of the ring resonators with the wavelengths of the corresponding laser sources.

A photonics transceiver is described herein, wherein the photonics transceiver exhibits improved areal bandwidth density and improved energy per bit consumption relative to conventional photonics transceivers. The photonics transceiver achieves an areal bandwidth density of at least 5 Tbps/mm.sup.2 with an energy consumption of less than 500 fJ/bit (sum of energy consumed for both a transmitted bit and a received bit). The photonics transceiver is a multi-chip module, where chips in the multi-chip module are tightly integrated with one another. The multi-chip module includes light source, photodetector, photonics, and control/logic chips. The photonics chip includes transparent conducting oxide integrated optical modulators and multiplexers and demultiplexers based on MEMS-tunable optical ring resonators.

A wavelength calibration method for a microring filter includes selecting N wavelengths from M wavelengths, and performing operations on the microring filter for each of the N wavelengths, thereby obtaining N sets of calibrated voltages, and obtaining, based on N sets of calibrated voltages, M−N sets of calibrated voltages corresponding to M−N wavelengths of the M wavelengths. The operating include adjusting thermal tuning power of the plurality of microrings in response to one set of voltages, and obtaining a plurality of sets of voltages that enable monitored optical power to have an extreme value, and using the plurality of sets of voltages as a reference, adjusting the thermal tuning power of the plurality of microrings in response to another set of voltages, and determining one of the N sets of calibrated voltages from the plurality of sets of voltages.