Methods and systems for a distributed Mach-Zehnder Interferometer (MZI) with an integrated feed forward equalizer (FFE) may include a photonic chip comprising an optical modulator having diode drivers, local voltage domain splitters, and delay elements, where each is distributed along a length of the optical modulator. Outputs of the delay elements may be coupled to inputs of the local domain splitters, and outputs of the local voltage domain splitters may be coupled to inputs of the diode drivers. A feed forward equalization (FFE) module comprising a configurable delay element with inverted outputs coupled to one of the delay elements along the length of the modulator, may be coupled to a local voltage domain splitter. An input electrical signal may be received and delayed using the delay elements and coupled to the local domain splitters, and input electrical signals for the diode drivers may be generated using the local domain splitters.

An optical dispersion compensator integrated with a silicon photonics system including a first phase-shifter coupled to a second phase-shifter in parallel on the silicon substrate characterized in an athermal condition. The dispersion compensator further includes a third phase-shifter on the silicon substrate to the first phase-shifter and the second phase-shifter through two 22 splitters to form an optical loop. A second entry port of a first 22 splitter is for coupling with an input fiber and a second exit port of a second 22 splitter is for coupling with an output fiber. The optical loop is characterized by a total phase delay tunable via each of the first phase-shifter, the second phase-shifter, and the third phase-shifter such that a normal dispersion (>0) at a certain wavelength in the input fiber is substantially compensated and independent of temperature.

Carrier suppression (CS-M-PAM) may be applied to M-PAM modulated optical signals to improve transmission reach. Additional rescaling of CS-M-PAM, referred to as adaptive CS-M-PAM, may further improve transmission reach by reducing low level symbol interference.

The present disclosure relates to a surveying instrument including a chassis, an optical system having an optical axis, a stage attached to the chassis and an optical component. The optical system may be adapted to receive and/or transmit light. The optical component is located at, or in proximity to, the optical axis. The received and/or transmitted light passes through the optical component. The stage includes an actuating member arranged to act on the optical component for movement thereof. The actuating member may be responsive to temperature so as to induce a displacement of the optical component relative to the chassis along the optical axis in response to a temperature change.

Modulation electrodes, bias electrodes, and bias electrodes are disposed in this order in a light wave-travelling direction in an optical modulation region modulating light having a wavelength. On the other hand, in an optical modulation region modulating light having a wavelength, the bias electrodes, the bias electrodes, and the modulation electrodes are disposed in this order in the light wave-travelling direction. That is, an order of the modulation electrodes and the bias electrodes in a longitudinal direction of a substrate is changed for each of the wavelengths.

In an optical waveguide device having a plurality of intersections between a convex optical waveguide and a signal electrode, the generation of disturbance modulation at the intersections is effectively reduced, thereby achieving good operating characteristics. An optical waveguide device includes a substrate on which an optical waveguide is formed, an intermediate layer formed on the substrate, and a signal electrode and a ground electrode formed on the intermediate layer, in which the optical waveguide includes a protruding portion extending on the substrate, the signal electrode has an action portion that extends along the optical waveguide and controls a light wave propagating through the optical waveguide, and an intersection that crosses over the optical waveguide, and the intermediate layer is formed such that a thickness at the intersection is thicker than a thickness at the action portion.

An optical modulator includes first and second waveguides; a first phase shifter provided in at least one of the first and second waveguides and configured to control a phase of the laser beam; a first optical element configured to combine the laser beam propagating through the first waveguide and the laser beam propagating through the second waveguide and separate the combined laser beam into two laser beams; a third (fourth) waveguide on which one (the other) of the laser beams separated by the first optical element is incident; a second phase shifter provided in at least one of the third and fourth waveguides and configured to control a phase of the laser beam; and a second optical element configured to combine the laser beam propagating through the third waveguide and the laser beam propagating through the fourth waveguide and emit the laser beam in the superposition state.

An optical device may comprise a laser configured to generate an optical beam and a Mach-Zehnder Interferometer (MZI) configured to amplify the optical beam. The MZI may comprise a first coupler and a second coupler connected via a plurality of arms of the MZI. An arm, of the plurality of arms, may provide an optical path for part of the optical beam and may comprise a semiconductor optical amplifier (SOA) configured to amplify the part of the optical beam and a phase shifter configured to adjust a phase of the part of the optical beam.

An on-chip Fourier transform spectrometer based on a double-layer spiral waveguide comprises, in order, a waveguide input coupler, a 1?N optical splitter, N double-layer waveguide Y-branch structures, N double-layer spiral waveguides with incremental lengths, N double-layer waveguide Y-branch structures arranged in opposite directions, and N germanium-silicon detectors. The group index difference between the odd mode and the even mode in the double-layer waveguide makes the double-layer spiral waveguide function like an asymmetric Mach-Zehnder interferometer. N double-layer spiral waveguides with incremental lengths are used to achieve a spatial heterodyne based Fourier transform spectrometer. Spectral reconstruction from the measured interference fringes can be achieved by a regression algorithm. The invention meets the application need for miniaturization and portability of Fourier transform spectrometers, and has lower temperature sensitivity compared with the existing on-chip spectrometers on the silicon platform.

An optoelectronic oscillator (OEO) is disclosed comprising an electronically tunable filter for transposing narrow pass band characteristics of a surface acoustic wave (SAW) filter to a microwave frequency to provide mode selection in the OEO. An OEO is disclosed comprising a set of optical domain components, a downconverter in communication with an output of the optical domain components, and a set of radio frequency (RF) domain components in communication with an output of the downconverter. The set of RF domain components comprises a tunable filter operating at a filter center frequency and having an output coupled to the set of optical domain components for communicating a mode selection result. The tunable filter including a tuner; and a sub-filter. The sub-filter operating at a fixed center frequency to provide mode selection and adjacent mode suppression with respect to the tunable filter center frequency. The sub-filter center frequency being lower than the tunable filter center frequency, and a ratio of the tunable filter center frequency to a bandwidth of the sub-filter being at least 1000:1.