An optical modulator includes a plurality of Mach-Zehnder optical modulation units. Each of the plurality of Mach-Zehnder optical modulation units include a pair of first signal wirings, a pair of first ground wirings, a pair of first signal electrode pads, and a pair of first ground electrode pads. The pair of first ground electrode pads is displaced by less than the first interval from the pair of first signal electrode pads so as to separate from a center line of each of the plurality of Mach-Zehnder optical modulation units.

An optical transceiver including a submount, a Mach-Zehnder Modulator (MZM), bonding wires, and a low pass filter type matching network is provided. The MZM includes an input port and an output port and disposed on the submount. The bonding wires are coupled to the submount and the MZM. The low pass filter type matching network is coupled to the bonding wires and is configured to absorb inductance of the bonding wires at a high frequency.

An electro-optic device is provided with a substrate, an optical waveguide formed of a lithium niobate film with a ridge shape on the substrate, and an electrode that applies an electric field to the optical waveguide. The optical waveguide includes a first waveguide section provided at least in an electric field application region applied with the electric field and having a thickness of 1 μm or larger and a second waveguide section provided in a region other than the electric field application region and having a thickness of 0.3 μm or larger and less than 1 μm.

A novel transmitter is proposed that provides broadband all-optical linearization of a Mach-Zehnder interferometer (MZI) modulator for use in high linearity RF photonic links and optical up-converter and down-converter schemes. It is based on an amplitude modulated (AM) MZI modulator where part of the laser Carrier is passed around the MZI modulator and added back to the AM signal, creating a Controlled Carrier-AM (CC-AM) signal. In this new scheme, a dual output MZI modulator is utilized, and the alternative output (Carrier*) is used together with the Carrier from the laser to create a new signal, LO*, which when coherently combined with the AM signal can reduce or completely cancel its 3rd order intermodulation distortion.

An optical modulator includes: a Mach-Zehnder modulator; and a processor that controls a bias of the Mach-Zehnder modulator. The Mach-Zehnder modulator includes first and second Mach-Zehnder interferometers that are respectively formed on first and second optical paths, a phase shifter that adjusts a phase difference between the first optical path and the second optical path. The processor outputs a first bias signal for controlling an operation point of the first Mach-Zehnder interferometer, a second bias signal for controlling an operation point of the second Mach-Zehnder interferometer, and a third bias signal for controlling a phase-shift amount of the phase shifter, a low-frequency signal being superimposed on the third bias signal. The processor controls the first through third bias signals based on a frequency component of the low-frequency signal that is included in the optical signal output from the Mach-Zehnder modulator.

A semiconductor device include: a first bus waveguide; a first silicon ring optically coupled to the first bus waveguide; a backup silicon ring optically coupled to the first bus waveguide; a first heater and a second heater configured to heat the first silicon ring and the backup silicon ring, respectively; and a first switch, where the first switch is configured to electrically couple the first silicon ring to a first radio frequency (RF) circuit when the first switch is at a first switching position, and is configured to electrically couple the backup silicon ring to the first RF circuit when the first switch is at a second switching position.

In an optical waveguide element which uses a rib type optical waveguide, light propagating in the rib type optical waveguide is monitored stably and accurately. The optical waveguide element includes a rib type optical waveguide provided on a optical waveguide substrate and configured of a convex portion protruding in a thickness direction of the optical waveguide substrate and extending in a plane direction of the optical waveguide substrate, and a light receiving element configured of a light receiving part formed on a light receiving element substrate disposed on the rib type optical waveguide and configured to receive at least a part of light propagating through the rib type optical waveguide, and the light receiving element substrate is supported by at least one first convex portion having the same height as that of the rib type optical waveguide provided on the optical waveguide substrate.

A method of characterizing a traveling-wave Mach-Zehnder modulator (TWMZM) includes measuring an electrooptic parameter, such as S21, of a test structure including a test TWMZM and a first instance of electrical pads which are connected to deliver a radio frequency (RF) signal to electrooptically modulate light traveling through the test TWMZM. The electrooptic parameter is similarly measured of a reference structure including a reference TWMZM and a second instance of the electrical pads which are connected to deliver the RF signal to electrooptically modulate light traveling through the reference TWMZM. A vestigial traveling-wave electrooptic phase modulator of the reference TWMZM is shorter than a traveling-wave electrooptic phase modulator of the test TWMZM. An electrooptic characteristic of the test TWMZM, such as S21 bandwidth, is determined by operations including subtracting the measured electrooptic S21 of the reference structure from the measured electrooptic S21 of the test structure.

Optical modulators with semiconductor based optical waveguides interacting with an RF waveguide in a traveling wave structure. The semiconductor optical waveguide generally comprise a p-n junction along the waveguide. To reduce the phase walk-off between the optical signal and the RF signal, the traveling wave structure can comprise one or more compensation sections where the phase walk-off is reversed. The compensation sections can comprise a change in dopant concentrations, extra length for the optical waveguide and/or extra length for the RF waveguide. Corresponding methods are described.

Various embodiments of a coplanar waveguide (CPW) transmission line as well as a silicon-based electro-optic (E-O) modulator comprising the CPW transmission line are described. The CPW transmission line has a curved or winding shape. The silicon-based E-O modulator includes a rib optical waveguide, a beam splitter, a beam combiner, and a CPW transmission line that exhibits the winding shape. At least one of the two optical arms of the rib optical waveguide alternately and periodically extends through a first groove and a second groove of the CPW transmission line. The plurality of active sections of the rib optical waveguide are evenly distributed on both sides of the CPW transmission line to suppress undesired transmission modes. An increased length of transmission path of the rib optical waveguide is also avoided or minimized, thereby reducing the transmission speed mismatch of the E-O modulator, which is essential for achieving high-speed operation.