An electro-optic Mach-Zehnder modulator includes a first optical waveguide forming a first arm of the Mach-Zehnder modulator, and a second optical waveguide forming a second arm thereof. The first or second optical waveguide includes capacitive segments that are spaced apart from one another, each forming an electrical capacitor. A travelling wave electrode arrangement applies a voltage across the first or second optical waveguide. The travelling wave electrode arrangement includes waveguide electrodes arranged on the capacitive segments , an electrical line extending along a part of the first or second optical waveguide, the electrical line being arranged a distance from the waveguide electrodes, and connecting arrangements, each being assigned to one of the waveguide electrodes. Each connecting arrangement includes at least two connecting structures spaced apart from one another wherein the waveguide electrodes each are electrically connected to the electrical line via the assigned two connecting structures.

A device and a method of fabricating the device are provided. The device includes an optical modulator formed in a dielectric material, a silicon substrate adjacent the dielectric material, and a metal shield formed in the dielectric material between the optical modulator and the silicon substrate. The metal shield blocks an electromagnetic field of a driving signal of the optical modulator from extending into the silicon substrate.

An electrical line arrangement, comprising a first and a second electrical line forming a coplanar strip line and at least one terminating resistor terminating the first and the second electrical line, is provided. In a first region of the electrical line arrangement the first and the second electrical line extend in a first distance from one another and in a second region of the electrical line arrangement the first and the second electrical line extend in a second distance from one another that is larger than the first distance. The terminating resistor is physically arranged at a position between the first and the second electrical line in the second region of the electrical line arrangement. At least one electrically conductive structure is arranged between the first and the second electrical line at least partially in the second region of the electrical line arrangement.

A distributed traveling-wave Mach-Zehnder modulator driver having a plurality of modulation stages that operate cooperatively (in-phase) to provide a signal suitable for use in a 100 Gb/s optical fiber transmitter at power levels that are compatible with conventional semiconductor devices and conventional semiconductor processing is described.

An optical device is described. This optical device includes an electro-optical material having an X-cut, Y-propagate orientation. In particular, a Y crystallographic direction of the electro-optical material is parallel to an optical waveguide defined in the electro-optic material and an X crystallographic direction of the electro-optical material is parallel to a vertical direction of the optical device. By applying drive signals having an angular frequency to the electro-optic material, the optical device may perform modulation, corresponding to a traveling-wave configuration, of an optical signal based at least in part on the drive signals. where the modulation involves a polarization conversion and a frequency shift. The angular frequency of the drive signals may be selected to approximately cancel electro-optic cross terms in X-Z plane of the electro-optical material. Moreover, an amplitude of the drive signals may be selected so that the optical device emulates a half-wave-plate configuration.

The MZ type optical modulator of the invention includes: a Si optical modulator including an input optical waveguide, two arm waveguides branching and guiding light input from the input optical waveguide, an output optical waveguide combining the light guided through the two arm waveguides and outputting the combined light, two signal electrodes for applying radio frequency signals that are arranged in parallel to the two arm waveguides respectively, and a DC electrode for applying a bias voltage that is provided between the two signal electrodes; and at least one ground electrode arranged in parallel to the two signal electrodes.

A velocity mismatch between optical signals and microwave electrical signals in electro-optic devices, such as modulators, may be compensated by utilizing different lengths of bends in the optical waveguides as compared to the microwave electrodes to match the velocity of the microwave signal propagating along the coplanar waveguide to the velocity of the optical signal. To ensure the electrode bends do not affect the light in the optical waveguide bends, the electrode may have to be rerouted, e.g. above or below, the optical waveguide layer. To ensure that the pair of optical waveguides have the same optical length, a waveguide crossing may be used to cross the first waveguide through the second waveguide.

A distributed traveling-wave Mach-Zehnder modulator driver having a plurality of modulation stages that operate cooperatively (in-phase) to provide a signal suitable for use in a 100 Gb/s optical fiber transmitter at power levels that are compatible with conventional semiconductor devices and conventional semiconductor processing is described.

The present invention provides an optical modulator including a substrate and a phase modulation portion on the substrate. The phase modulation portion includes an optical waveguide comprised of a first clad layer, a semiconductor layer that is laminated on the first clad layer and has a refraction index higher than the first clad layer and a second clad layer that is laminated on the semiconductor layer and has a refraction index lower than the semiconductor layer, a first traveling wave electrode, and a second traveling wave electrode. The semiconductor layer includes a rib that is formed in the optical waveguide in an optical axis direction and is a core of the optical waveguide, a first slab that is formed in the optical axis direction in one side of the rib, a second slab that is formed in the optical axis direction in the other side of the rib, a third slab that is formed in the first slab in the optical axis direction at the opposite side to the rib, and a fourth slab that is formed in the second slab in the optical axis direction at the opposite side to the rib. The first slab is formed to be thinner than the rib and the third slab, and the second slab is formed to be thinner than the rib and the fourth slab.

Provided is an optical-waveguide-element module in which a common connecting substrate is used for different optical waveguide elements and deterioration of the propagation characteristics of electrical signals in a curved section of a signal electrode is suppressed. A control electrode in an optical waveguide element is consisted of a signal electrode SL and ground electrodes GD which put the signal electrode therebetween, a connecting substrate is provided with a signal line SL1 (SL2) and ground lines GD1 (GD2) which put the signal line therebetween, the signal electrode and the signal line, and, the ground electrodes and the ground lines are respectively connected to each other using wires (WR1, WR2, and WR20 to WR22), the control electrode in which a space W1 between the ground electrodes GD at an input end or an output end of the control electrode is wider than a space W2 between the ground lines GD1 (GD2) on the optical waveguide element side in the connecting substrate, has a portion in which the space between the ground electrodes GD forms a space W3 which is narrower than the space W2 in a portion away from the input end or the output end, furthermore, the signal electrode SL in the control electrode has a curved section in a place from the input end or the output end to an operating part in which the control electrode applies an electric field to the optical waveguide, and suppression means (WR20 to WR32) for suppressing generation of a local potential difference between the ground electrodes which put the signal electrode therebetween in the curved section of the signal electrode is provided.