An optical modulator circuit includes first and second electrodes, first and second p-n junction segments (PNJSs), and first and second optical waveguides. The first PNJS includes a first modulating p-n junction (MPNJ) in series with a first non-modulating device (NMD) that are connected to the first and second electrodes, respectively, where the first NMD includes a first substantially larger capacitance than the first MPNJ. The second PNJS includes a second NMD in series with a second MPNJ that are connected to the first and second electrodes, respectively, where the second NMD includes a second substantially larger capacitance than the second MPNJ. The first and second optical waveguides superimpose the first and second MPNJs, respectively, where the first and second MPNJs are configured to modulate a refractive index of the first and second optical waveguides, respectively, based on the substantially larger capacitance of the first NMD and the second NMD.

An electro-optical modulator device is provided. The electro-optical modulator device comprises at least one electro-optical modulator having a first and a second optical waveguide and an electrode arrangement for applying a voltage across the optical waveguide, wherein the electrode arrangement comprises a plurality of first waveguide electrodes and a plurality of second waveguide electrodes arranged on top of the first and the second optical waveguide, respectively, wherein the first and second waveguide electrodes are capacitively coupled to one another; and at least one driver unit for supplying a voltage to the electrode arrangement; and an electrical connection between the driver unit and the electrode arrangement. The electrical connection between the driver unit and the electrode arrangement comprises a flexible coplanar strip line.

A technique for tuning a silicon photonics (SiP) based nested (parent/child) Mach-Zehnder modulator (MZM). The technique includes a sequence of applying dither tones on individual arms of the child MZMs, observing changes in the output of the MZM, and adjusting the MZM until reaching the null points for the child MZMs and the quad point for the parent MZM.

The present invention relates to telecommunication techniques and integrated circuit (IC) devices. More specifically, embodiments of the present invention provide an off-quadrature modulation system. Once an off-quadrature modulation position is determined, a ratio between DC power transfer amplitude and dither tone amplitude for a modulator is as a control loop target to stabilize off-quadrature modulation. DC power transfer amplitude is obtained by measuring and sampling the output of an optical modulator. Dither tone amplitude is obtained by measuring and sampling the modulator output and performing calculation using the optical modulator output values and corresponding dither tone values. There are other embodiments as well.

An electro-optical modulator is provided. The electro-optical modulator comprises at least one optical waveguide, an electrode arrangement for applying a voltage across the optical waveguide. The electrode arrangement comprises a first and a second electrical line and at least two terminating resistors terminating the first and the second electrical line. The electrode arrangement comprises at least one capacitive structure that capacitively couples, but galvanically separates the two terminating resistors. The capacitive structure comprises at least two electrically conductive layers physically arranged at a position between the first and the second electrical line, wherein the at least two layers are separated by at least one dielectric layer.

This optical modulation element includes a first optical waveguide, a second optical waveguide, a first electrode for applying an electric field to the first optical waveguide, and a second electrode for applying an electric field to the second optical waveguide. The first optical waveguide and the second optical waveguide each include a ridge-shaped portion protruding from a first surface of a lithium niobate film. A first interaction length L.sub.1 that is a length of a part of the first electrode overlapping the first optical waveguide in a longitudinal direction is 0.9 mm or more and 20 mm or less. A second interaction length L.sub.2 that is a length of a part of the second electrode overlapping the second optical waveguide in the longitudinal direction is 0.9 mm or more and 20 mm or less.

In photonic integrated circuits implemented in silicon-on-insulator substrates, non-conductive channels formed, in accordance with various embodiments, in the silicon device layer and/or the silicon handle of the substrate in regions underneath radio-frequency transmission lines of photonic devices can provide breaks in parasitic conductive layers of the substrate, thereby reducing radio-frequency substrate losses.

An optical IQ modulator (IQM) including two parallel Mach-Zehnder modulators (MZM1, MZM2) generates single sideband data signals. A control unit (18) generates additional optical single sideband pilot signals (PS1, PS2) positioned in a lower and a higher sideband respectively, and also further pilot signals (PS3, PS4) in both sidebands. A IQ modulator output signal (MOS) converted into electrical monitoring signals (MOS) and monitored. A control unit (18) selects control signals (CS12, CS3, CS4) and controls the IQ modulator via its bias ports (6, 7, 8) till the power transfer functions (PTF) of the Mach-Zehnder modulators (MZM1, MZM2) and the phase difference (ΔΦ) between their output signals is optimized.

There is provided an optical transmitter including a memory, a processor coupled to the memory and the processor to generate an electric signal, an optical generator to generate light, an optical modulator to modulate the light with the electric signal to create an optical signal, a first voltage electrode to apply a first voltage to the optical signal, a second voltage electrode to apply a second voltage to the optical signal to which the first voltage is applied, and a detector to detect an optical power of the optical signal to which the second voltage is applied, wherein the processor stops generating the electric signal, controls the first voltage electrode to change the first voltage after the stop of generating the electric signal, and controls the second voltage electrode to change the second voltage according to the detected optical power after the change of the first voltage.

The substrate-type optical waveguide includes a rib-slab type core. A depletion layer exists in a rib part and, in any cross section of the core, a width of a first slab part is set to be greater than a width of a second slab part.