The present invention discloses a directional photonic coupler (1) with independent tuning of the coupling factor and phase difference. The coupler comprises: two waveguides (4, 5), with respective propagation constants “β.sub.1, β.sub.2”, on which phase shifters (6, 7) configured to modify the propagation coefficients are located. Both phase shifters are configured such that, by independent modification (differential or unique) of the propagation coefficients, the power coupling factor (K) between an input signal (2a or 2b) and the output signals (3b and 3a) is tuned, and by equal and simultaneous modification of the propagation coefficients, the common phase difference of the optical output signals (3 a, 3b) is tuned. A third phase shifter (15) can be used to retune the phase difference at the input/output of one of the waveguides. The coupler is of particular interest in PIC circuits, coupled resonators, Mach-Zehnder interferometers and mesh structures.

A wavelength division multiplexing filter comprises: a first multi-order Mach-Zehnder interferometer comprising a plurality of first-order Mach-Zehnder interferometers, and a second multi-order Mach-Zehnder interferometer comprising a plurality of first-order Mach-Zehnder interferometers; wherein the first multi-order Mach-Zehnder interferometer and the second multi-order Mach-Zehnder interferometer are included in a group of multiple multi-order Mach-Zehnder interferometers arranged within a binary tree arrangement, the binary tree arrangement comprising: a first set of a plurality of multi-order Mach-Zehnder interferometers, the first set including the first multi-order Mach-Zehnder interferometer, and having an associated spectral response with a first spacing between adjacent passbands, and a second set of at least twice as many multi-order Mach-Zehnder interferometers as in the first set, the second set including the second multi-order Mach-Zehnder interferometer, and having an associated spectral response with a second spacing between adjacent passbands that is twice the first spacing.

A wavelength demultiplexer includes a photonic circuit and a control circuit that adjusts wavelength characteristics of the photonic circuit. The photonic circuit converts two orthogonal polarized waves contained in the incident light into two same polarized waves, which are supplied to a first optical demultiplexing circuit and a second optical demultiplexing circuit provided in the photonic circuit and having the same configuration. The photonic circuit supplies a total output power of monitor lights extracted from the same positions in the first optical demultiplexing circuit and the second optical demultiplexing circuit to the control circuit. The control circuit controls a first wavelength characteristic of the first optical demultiplexing circuit and a second wavelength characteristic of the second optical demultiplexing circuit based on the total output power of the monitor lights.

A waveguide division multiplexer and demultiplexer includes a first-stage Mach-Zehnder interferometer (MZI) and two second-stage MZIs. The first-stage MZI includes two input ends and two output ends, in which one of the inputs is configured to receive an input optical beam with a first center wavelength and a second center wavelength, and the output ends are configured to respectively transmit first-stage output optical beams respectively with the first center wavelength and the second center wavelength. One input terminals of the second-stage MZI are configured to respectively receive the first-stage output optical beams, and one output terminals of the second-stage MZI are configured to transmit second-stage output optical beams with the first and second center wavelengths, respectively. Each second-stage MZI is configured in cross-state condition.

A Mach-Zehnder interferometer (MZI) filter comprising one or more passive compensation structures are described. The passive compensation structures yield MZI filters that are intrinsically tolerant to perturbations in waveguide dimensions and/or other ambient conditions. The use of n+1 waveguide widths can mitigate n different sources of perturbation to the filter. The use of at least three different waveguide widths for each Mach-Zehnder waveguide can alleviate sensitivity of filter performance to random width or temperature variations. A tolerance compensation portion is positioned between a first coupler section and a second coupler section, wherein the tolerance compensation portion includes a first compensation section having a second width, a second compensation section having a third width and a third compensation section having a fourth width, wherein the fourth width is greater than the third width and the third width is greater than the second width.

A silicon photonic integrated chip and a wavelength division multiplexer that includes at least two polarization control structures and at least one polarization-independent Mach-Zehnder interferometer on a silicon substrate are provided. The polarization control structure includes two input ports and one output port. The Mach-Zehnder interferometer includes two input ports and one optical signal output port for outputting a multiplexed optical signal. The output ports of the polarization control structures are connected to the input ports of the Mach-Zehnder interferometer. The polarization control structures have large bandwidths for increasing an optical bandwidth of the wavelength division multiplexer and reducing an optical loss. A quantity of phase shift arms that require tuning feedback is reduced to lower overall power consumption of the wavelength division multiplexer. Reliability and yields of the wavelength division multiplexer are enhanced due to a large manufacturing tolerance and good stability of the polarization control structures.

Systems and methods here may include improved tunable lasers having a tunable filter and a tunable channel selector that can control precisely the wavelength and the bandwidth of the light emitted by the laser, while suppressing light that may otherwise be emitted by the laser outside the desired wavelength and bandwidth with unidirectional ring lasers having a resonator of which forms a ring and where light propagates only in one of the two possible directions.

Methods, devices, and systems for processing information are disclosed. An example device may comprise a metastructure comprising a plurality of physical features configured to transform an analog signal according to a kernel of an integral equation. The device may comprise one or more waveguides coupled to the metastructure and configured to recursively supply a transformed analog output signal of the metastructure to an input of the metastructure to iteratively cause one or more transformed analog signals output from the metastructure to converge to an analog signal representing a solution to the integral equation.

An approach for realizing low-power, high-port-count optical switching systems, such as OXCs, WXCs, and ROADMs is presented. Optical switching systems in accordance with the present disclosure include arrangements of frequency-filter blocks, each of which includes a cascaded arrangement of tunable couplers and tunable Mach-Zehnder Interferometers (MZIs) that provides a substantially flat-top broadband transfer function for the frequency-filter block. The tunability for these devices is achieved by operatively coupling a low-power-dissipation phase controller, such as a stress-optic phase controller or liquid-crystal-based phase controller with one arm of the device, thereby enabling control over the coupling coefficient of the device.

In some embodiments, the present disclosure relates to a device having a first waveguide and a second waveguide arranged over a substrate. The first waveguide has a first input terminal and a first output terminal, wherein the first input terminal is configured to receive light. The second waveguide is arranged laterally beside the first waveguide and has a second input terminal and a second output terminal. The second input terminal of the second waveguide is configured to receive light. The first waveguide further includes a first portion that has a different structure than surrounding portions of the first waveguide. The second waveguide further includes a second portion that has a different structure than surrounding portions of the second waveguide. The first waveguide is spaced apart at a maximum distance from the second waveguide at the first portion and the second portion.