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 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 thermally tunable waveguide including an optical waveguide and a heater is provided. The optical waveguide includes a phase shifter. The heater is disposed over the optical waveguide. The heater includes a heating portion, pad portions and tapered portions. The heating portion overlaps with the phase shifter of the optical waveguide. The pad portions are disposed aside of the heating portion. Each of the pad portions is connected to the heating portion through one of the tapered portions respectively.

A photonic integrated circuit (PIC) for determining a wavelength of an input signal is disclosed. The PIC comprises: a substrate; a first Mach-Zehnder Interferometer (MZI) disposed over the substrate, comprising first optical waveguides having a first optical path length difference, and configured to receive a first output optical signal from a light source. The PIC also comprises a second Mach-Zehnder Interferometer (MZI) disposed over the substrate, comprising second optical waveguides having a second optical path length difference, which is greater than the first optical path length difference, and configured to receive a second output optical signal from the light source.

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.

A demultiplexer for use in a wavelength division multiplexed system. The demultiplexer comprises: an input waveguide, configured to receive a wavelength division multiplexed signal; a demultiplexing element, configured to demultiplex the multiplexed signal received from the input waveguide into a plurality of multi-mode demultiplexed signal components; a multi-mode output waveguide, the multi-mode output waveguide being coupled to the demultiplexing element and configured to receive one of the multi-mode demultiplexed signal components; and a splitter, coupled to the multi-mode output waveguide, and configured to split the received multi-mode demultiplexed signal component into two single-mode outputs.

The application provides a interface light path structure with all polarization-maintaining function. A first polarization-maintaining-transferring device includes a first port, a second port, and a third port, wherein the first port receives a first polarized light output by the polarization beam-splitting device, the second port is connected to the first Faraday rotation mirror, and the third port is connected to a first port of the first polarization-maintaining coupler. A second polarization-maintaining-transferring device includes a first port, a second port, and a third port, wherein the first port receives a second polarized light output by the polarization beam-splitting device, the second port is connected to the second Faraday rotation mirror, and the third port is connected to a second port of the first polarization-maintaining coupler.

An on-chip interferometer and a spectrometer including the interferometer are provided. An on-chip interferometer includes a waveguide for propagation of an optical signal including an input waveguide; at least two interferometer arms having one or more slot waveguides; and an output waveguide; wherein the input waveguide is split into the at least two interferometer arms which are recombined into the output waveguide; and a control mechanism configured for controlling a relative time delay between optical signals propagating in the two interferometer arms by modifying one or more slot widths of one or more of the slot waveguides; and wherein the relative time delay is at least 1, 2, 5, or at least 10 fs or at least one optical period of the longest optical wavelength of the optical signal.

A signal generator includes a photonic circuit configured to output a sequence of solitons at a known rate. The solitons illuminate a high-speed photodiode that, in response, generates an electrical signal, such as a sinusoidal signal, which can be provided as input to a direct digital synthesizer configured to output successive phases of a selected waveform in response to electrical stimulus.

Fabrication-tolerant on-chip multiplexers and demultiplexers are provides via a lattice filter interleaver configured to receive an input signal including a plurality of individual signals and to produce a first interleaved signal with a first subset of the plurality of individual signals and a second interleaved signal with a second subset of the plurality of individual signals; a first Bragg interleaver configured to receive the first interleaved signal and produce a first output signal including a first individual signal of the plurality of individual signals and a second output signal including a second individual signal of the plurality of individual signals; and a second Bragg interleaver configured to receive the second interleaved signal and produce a third output signal including a third individual signal of the plurality of individual signals and a fourth output signal including a fourth individual signal of the plurality of individual signals.