Abstract: A system, e.g. a reconfigurable electro-optical network, includes input and output waveguides. The input waveguide is configured to receive a first input optical signal including a first modulated input wavelength channel. The output waveguide is configured to receive a carrier signal including an unmodulated output wavelength channel. An input microcavity resonator is configured to derive a modulated electrical control signal from the modulated input wavelength channel. A first output microcavity resonator is configured to modulate the output wavelength channel in response to the control signal.

Abstract: An optical modulation apparatus, including: a Mach-Zehnder optical modulator having two light waveguides, two output light waveguides, and a join-and-branch portion located therebetween; a drive circuit configured to output a modulation signal to modulation electrodes provided respectively on the two light waveguides as a differential signal, the modulation signal modulating lights propagated in the two light waveguides; a phase adjustment circuit configured to control first phase control signals to be output to phase adjustment electrodes provided respectively on the two light waveguides, and adjust phases of lights propagated in the two light waveguides; a phase shift control circuit configured to switch second phase control signals to be output to phase shift electrodes provided respectively on the two light waveguides, and change phases of the lights propagated in the two light waveguides; and a signal polarity reversal circuit configured to reverse a polarity of the differential signal.

Abstract: A semiconductor-based optical modulator is presented that includes a separate phase control section to adjust the amount of chirp present in the modulated output signal. At least one section is added to the modulator configuration and driven to create a pure “phase” signal that will is added to the output signal and modify the ei? term inherent in the modulation function. The phase modulation control section may be located within the modulator itself, or may be disposed “outside” of the modulator on either the input waveguiding section or the output waveguiding section. The phase control section may be formed to comprise multiple segments (of different lengths), with the overall phase added to the propagating signal controlled by selecting the different segments to be energized to impart a phase delay to a signal propagating through the energized section(s).

Abstract: An electro-optic modulator includes a substrate, a pair of transmission lines, a first strip-shaped electrode, and a pair of second strip-shaped electrodes. The substrate includes a surface and a reversely-polarized portion. The transmission lines are formed in the surface and extend substantially in parallel with each other. One of the transmission lines is formed within the reversely-polarized portion and the other is out of the reversely-polarized portion. The first strip-shaped electrode is formed on the surface and covers the transmission lines. The second strip-shaped electrodes are positioned at two sides of the first strip-shaped electrodes and parallel with the first strip-shaped electrode.

Abstract: An optical device includes a first waveguide extended in one direction. A second waveguide is positioned at a side of the first waveguide. The second waveguide includes the first conductive semiconductor layer, the second conductive semiconductor layer, and the undoped semiconductor layer positioned between the first conductive semiconductor layer and the second conductive semiconductor layer, wherein the undoped semiconductor layer has a refractive index larger than those of the first conductive semiconductor layer and the second conductive semiconductor layer. First and second electrodes are connected to the first conductive semiconductor layer and the second conductive semiconductor layer of the second waveguide, respectively.

Abstract: An electro-optic waveguide polarization modulator (20) comprising a waveguide core (4) having first and second faces defining a waveguide core plane, a plurality of primary electrodes (22, 24) arranged at a first side of the waveguide core plane and out of said plane, and at least one secondary electrode (26) arranged at a second side of the waveguide core plane and out of said plane, wherein the electrodes (22, 24, 26) are adapted in use to provide an electric field having field components (13, 15) in two substantially perpendicular directions within the waveguide core (4) so as modulate the refractive index thereof such that electromagnetic radiation propagating through the core (4) is converted from a first polarization state to a second polarization state.

Abstract: Disclosed herein is an optical frequency shifter (1) provided with: an electro-optical substrate (3) having a main surface (3a); an optical waveguide structure (2) formed in the substrate (3) and having two waveguide portions (7), which are spaced apart by a distance (S) such as to ensure mutual optical coupling therebetween; and an electrode structure (10) arranged above the main surface (3a) of the substrate (3) and having at least a first electrode (11). The substrate (3) has a Z-cut crystalline structure with Z crystal axis orthogonal to the main surface (3a) and comprises two oppositely poled portions (20, 21) having opposite orientations of the Z crystal axis; the two waveguide portions (7) are arranged underneath the first electrode (11), each in a respective one of the two oppositely poled portions (20, 21).

Abstract: In an optical modulator, respective lights for where one input light has been branched, are input via a curved waveguide to a plurality of optical modulation sections arranged in parallel on the same substrate. In a Mach-Zehnder type optical waveguide, a spacing between the pair of branching waveguides of the adjacent optical modulation sections, is formed so as to become wider in the vicinity of a border of an input side polarization inversion region than in the vicinity of a start point of an interaction portion. As a result, even if a signal electrode of the optical modulation sections shifts at the boundary portion of the polarization inversion region, the spacing between the signal electrodes does not become narrow, and hence the radius of curvature of curved waveguides for guiding the input light to the respective optical modulation sections can be increased, so that it becomes possible to apply input light to the optical modulation sections at low loss.

Abstract: An optical switch structure and a method for fabricating the optical switch structure provide at least two ring waveguides located and formed supported over a substrate. At least one of the at least two ring waveguides includes at least one PIN diode integral with the ring waveguide as a tuning component for an optical switch device that derives from the optical switch structure. The PIN diode includes different doped silicon slab regions internal to and external to the ring waveguide, and an intrinsic region there between that includes the ring waveguide. The method uses two photolithographic process steps, and also preferably a silicon-on-insulator substrate, to provide the ring waveguides formed of a monocrystalline silicon semiconductor material.

Abstract: The present invention is a method and an apparatus for dynamic manipulation and dispersion in photonic crystal devices. In one embodiment, a photonic crystal structure comprises a substrate having a plurality of apertures formed therethrough, a waveguide formed by “removing” a row of apertures, and a plurality of pairs of lateral electrical contacts, the lateral electrical contact pairs extending along the length of the waveguide in a spaced-apart manner. The lateral electrical contact pairs facilitate local manipulation of the photonic crystal structure's refractive index. Thus, optical signals of different wavelengths that propagate through the photonic crystal structure can be dynamically manipulated.

Abstract: The invention discloses a device for selecting pulses comprising an optical waveguide for guiding the optical radiation along an axis; comprising a first electro-optical modulator designed to modulate the optical transparency of the waveguide; comprising a second electro-optical modulator designed to modulate the optical transparency of the waveguide, wherein the first modulator and the second modulator are arranged one after the other on the axis of the waveguide, and further comprising at least one control circuit designed to actuate the first modulator and the second modulator at offset times, and characterized in that a substrate of a semiconductive material is provided, the waveguide and the at least one control circuit are arranged on the substrate.

Abstract: An optical modulator includes a modulator that modulates an input light of light by using an input signal. The optical modulator further includes a compensation circuit that compensates the phase of a signal light in accordance with an input current, the signal light being the input light modulated by the modulator. The optical modulator further includes a detector that detects the difference between the phase of the signal light compensated by the compensation circuit and the phase of an input signal that is input to the modulator. The optical modulator further includes an adjustment circuit that adjusts, in accordance with the phase difference detected by the detector, the input current that is input to the compensation circuit.

Abstract: The invention provides a semiconductor optical modulator including a two-step mesa optical waveguide having a first clad layer (101); a mesa-like core layer (102) formed over the first clad layer (101); and a second clad layer (103) formed into a mesa shape over the core layer (102), and having a mesa width smaller than that of the core layer (102). The two-step mesa optical waveguide includes a multi-mode optical waveguide region to which an electric field is applied or into which an electric current is injected, and a single-mode optical waveguide region to which the electric field is not applied and into which the electric current is not injected. When the mesa width of the core layer in the multi-mode optical waveguide region is defined as Wmesa1, and the mesa width of the core layer in the single-mode optical waveguide region is defined as Wmesa2, Wmesa1>Wmesa2 is satisfied.

Abstract: In a light control element comprising a thin plate having a thickness of 10 [mu]m or less and exhibiting electro optic effect, an optical waveguide formed on the thin plate, and a control electrode for controlling light passing through the optical waveguide, the control electrode includes a first electrode and a second electrode so arranged as to sandwich the thin plate, and the first electrode has a coplanar electrode consisting of a first signal electrode and a ground electrode, while the second electrode has a second signal electrode. Modulation signals having mutually inverted amplitudes are inputted to the first signal electrode of the first electrode and the second signal electrode of the second electrode such that the modulation signals cooperate to apply an electric field to the optical waveguide.

Abstract: An optical amplifier includes a passive waveguide region and an active waveguide region. The passive waveguide region is configured to receive an incident optical signal and adjust a mode of the optical signal. The active waveguide region is integrated to the passive waveguide region and configured to perform gain modulation on the optical signal received from the passive waveguide region by changing density of carriers in response to a current applied to the active waveguide region. Internal loss of the active waveguide region is adjusted to produce a resonance effect and thereby to increase bandwidth of the active waveguide. Therefore, the optical amplifier can have a wide bandwidth under a low-current condition.

Abstract: A transmission line and method for implementing includes a plurality of segments forming an electrical path and a continuous optical path passing through the segments. Discrete inductors are formed between and connect adjacent segments. The inductors are formed in a plurality of metal layers of an integrated circuit to balance capacitance of an optical modulator which includes the transmission line to achieve a characteristic impedance for the transmission line.

Abstract: An electro-optic modulator includes a substrate comprising a surface, a pair of transmission lines formed in the surface and extending substantially in parallel with each other, a pair of first strip electrodes formed on the surface and covering the respective transmission lines, and a pair of second strip electrodes positioned at two sides of the first strip electrodes and parallel with the first strip electrodes.

Abstract: An optical waveguide device includes: a substrate which has an electro-optical effect; an optical waveguide which is formed on the substrate and/or inside the substrate; and an in-substrate electrode which is formed of a metal and provided inside the substrate.

Abstract: A new High-Z optical modulator has a waveguide and electrodes on a substrate, a buffer layer with a low dielectric constant between the waveguide and the substrate, and a substance between the waveguide and the substrate with a dielectric constant lower than a dielectric constant of the substrate to the side and below the plane of the waveguide, thereby improving electro-optic field overlap, increasing RF speed and increasing transmission line impedance. The material with a dielectric constant lower than the substrate extends between the waveguide and the electrodes to a depth below the waveguide equal to or greater than the lateral distance between the waveguide and electrodes. This material may be air and may be introduced by cutting away portions of the substrate around the waveguide with a precision dicing saw. The electrodes may be placed even with the waveguide or below the waveguide on the cut-away portion of the substrate.

Abstract: An optical XOR gate is formed as a photonic integrated circuit (PIC) from two sets of optical waveguide devices on a substrate, with each set of the optical waveguide devices including an electroabsorption modulator electrically connected in series with a waveguide photodetector. The optical XOR gate utilizes two digital optical inputs to generate an XOR function digital optical output. The optical XOR gate can be formed from III-V compound semiconductor layers which are epitaxially deposited on a III-V compound semiconductor substrate, and operates at a wavelength in the range of 0.8-2.0 ?m.

Abstract: A terahertz-wave element includes a waveguide (2, 4, 5) that includes an electro-optic crystal and allows light to propagate therethrough, and a coupling member (7) that causes a terahertz wave to enter the waveguide (2, 4, 5). The propagation state of the light propagating through the waveguide (2, 4, 5) changes as the terahertz wave enters the waveguide (2, 4, 5) via the coupling member (7).

Abstract: A digital data transmission device is provided comprising optical waveguide architecture, a sideband generator, a modulation controller, an optical filter, a data mapping unit, and a phase controller. The optical waveguide architecture is configured to direct an optical signal through the sideband generator and the optical filter. The sideband generator comprises an electrooptic interferometer comprising first and second waveguide arms. The modulation controller is configured to generate an electrical drive signal to drive the sideband generator at a control voltage that is substantially larger than V? to generate optical frequency sidebands about a carrier frequency of the optical signal. The optical filter is configured to discriminate between the optical frequency sidebands and the optical carrier frequency such that optical sidebands of interest can be directed through the optical waveguide architecture as an optical millimeter wave signal.

Abstract: A pluggable light source device connects in a plug-in engaging manner with an optical modulating device that includes an optical modulator component. The pluggable light source includes a light generator to generate an optical signal to be output from the light source device, and a connection member disposed at a connecting end of the light source device. The connection member includes an optical connector, where the optical connector of the light source device is configured to engage with a corresponding optical connector of the optical modulating device when the connecting end of the light source device is connected via a plug-in engagement with a connection member of the optical modulating device so as to facilitate input of optical signals from the light generator to the optical modulator component.

Abstract: An object of the invention is to provide a traveling-wave-type optical modulator capable of adjusting the frequency characteristics of an electric/optical conversion response over a wide frequency band, preventing the occurrence of jitter, and improving optical transmission characteristics. A traveling-wave-type optical modulator 20 includes: a substrate that has an electro-optical effect; an optical waveguide that is formed on the substrate; a modulating electrode that controls the modulation of a light wave traveling through the optical waveguide and includes a signal electrode portion 21 and a ground electrode portion; an input interface 22 that is connected to an input side of the signal electrode portion; a terminator 23 that is connected to the end of the signal electrode portion; and an adjustment filter 31 that is provided between the input interface and the signal electrode portion and adjusts frequency characteristics. It is preferable that the adjustment filter 31 be a passive filter.

Abstract: A method for manufacturing a modulator device is provided. The method includes providing an at least partially completed modulator having a top and a bottom and a substrate; fixedly mounting the top of the modulator on a mechanical support; removing from the bottom of the modulator a portion of the substrate, thereby forming a groove in the substrate; and separating the modulator with the groove from the mechanical support; wherein the reduced thickness of the substrate in the area of the groove restricts the flow of energy leakage into the substrate.

Abstract: Provided is an electro-optic modulating device. The electro-optic modulating device includes an optical waveguide with a vertical structure and sidewalls of the vertical structure are used to configure a junction.

Abstract: An optical control element capable of efficiently removing unnecessary higher mode light without complicating a manufacturing process of the optical control element is provided. The optical control element includes a substrate having an electro-optical effect, optical waveguides that are formed on the substrate, and a control electrode that controls light waves propagating through the optical waveguides, and the optical waveguides include an output waveguide portion which derives fundamental mode light, and a subsidiary waveguide portion which is connected to the output waveguide portion and derives higher mode light, and removal means is formed in contact with the subsidiary waveguide portion, for removing the higher mode light propagating through the subsidiary waveguide portion.

Abstract: An athermal ring optical modulator includes a first clad layer, a ring optical resonator, a second clad layer, an input-output optical waveguide, a first conduction type region, and a second conduction type region. The ring optical resonator has a rib optical waveguide with a convex portion formed on a semiconductor slab layer. The semiconductor slab layer is formed on the first clad layer. The second clad layer covers an upper side of the rib optical waveguide. The input-output optical waveguide couples optically with the ring optical resonator. The first and second conduction type regions are formed in the semiconductor slab layer inside and outside the ring optical resonator, respectively. In addition, the second clad layer includes a material having a negative thermo-optical coefficient. The semiconductor slab layer outside the convex portion is thinner than the semiconductor slab layer inside the convex portion.

Abstract: An optical device includes an active component on a base. The active component is a light sensor and/or a light modulator. The active component is configured to guide a light signal through a ridge of an active medium extending upwards from slab regions of the active medium. The slab regions are on opposing sides of the ridge. The active medium includes a doped region that extends into a lateral side of the ridge and also into one of the slab regions. The depth that the doped region extends into the slab region is further than the depth that the doped region extends into the ridge.

Abstract: An optical control device is provided which can suppress crosstalk between electrodes without increasing the entire size of the device itself. The optical control device includes a substrate having an electro-optical effect, an optical waveguide formed in the substrate, and a modulation electrode modulating optical waves propagating in the optical waveguide. The modulation electrode includes at least two signal electrodes and ground electrodes arranged to interpose the signal electrodes therebetween. The optical control device further includes an electrical connection member that electrically connects the ground electrode disposed between the two signal electrodes to other ground electrodes and that is disposed to cross over part of the signal electrode.

Abstract: An optical modulator includes a first coupler that branches an input light into two and outputs a first output light and a second output light; a first Mach-Zehnder interferometer (MZI) that modulates the intensity of the first output light from the first coupler and outputs a third output light; a second MZI that modulates the intensity of the second output light from the first coupler and outputs a fourth output light; a second coupler that combines the third output light from the first MZI and the fourth output light from the second MZI, branches a combined light into two, and outputs a fifth output light and a sixth output light. The interaction length of a branch of the first coupler and that of the second coupler are set such that the wavelength dependence of the splitting ratio of the first coupler is inversely related to that of the second coupler.

Abstract: An electro-optic modulator comprising a first region of silicon material and a second region of non-silicon material. The second region may at least partially overlap the first region to create a lateral overlap region. An optical waveguide of the modulator may be included in the lateral overlap region and comprise of both the silicon and the non-silicon material. The refractive index of at least one of the silicon material and the non-silicon material within the optical waveguide may change based on an electrical difference applied between electrical contacts of the modulator.

Abstract: Optical devices having a first semiconductor slab including a first lateral boundary for an optical mode and a second semiconductor slab above and asymmetrically overlapping the first lateral boundary included in the first semiconductor slab and including an edge of a second lateral boundary for the optical mode. The second lateral boundary is disposed above and to a side of the first lateral boundary. The first semiconductor slab is of a silicon material while the second semiconductor slab is of a III-V material. A first and a second electrical contact are coupled to the second semiconductor slab, one on each lateral side of the second lateral boundary. The optical device further includes an optical waveguide region formed by the first and second lateral optical mode boundaries, wherein a complex refractive index of the optical waveguide region changes based on an electrical difference applied between the first and second electrical contacts.

Abstract: A transmission line and method for implementing includes a plurality of segments forming an electrical path and a continuous optical path passing through the segments. Discrete inductors are formed between and connect adjacent segments. The inductors are formed in a plurality of metal layers of an integrated circuit to balance capacitance of an optical modulator which includes the transmission line to achieve a characteristic impedance for the transmission line.

Abstract: In an electro-optic device, a stack structure including a first silicon layer of a first conductivity type and a second silicon layer of a second conductivity type has a rib waveguide shape so as to form an optical confinement area, and a slab portion of a rib waveguide includes an area to which a metal electrode is connected. The slab portion in the area to which the metal electrode is connected is thicker than a surrounding slab portion. The area to which the metal electrode is connected is set so that a range of a distance from the rib waveguide to the area to which the metal electrode is connected is such that when the distance is changed, an effective refractive index of the rib waveguide in a zeroth-order mode does not change.

Abstract: A semiconductor optical modulator includes a substrate; and a mesa portion having a first cladding layer disposed on the substrate, a core layer disposed on the first cladding layer, and a second cladding layer disposed on the core layer, the first cladding layer having a first conductivity type, the second cladding layer having a second conductivity type reverse to the first conductivity type. The core layer includes a first multi quantum well structure made from a first conductivity type semiconductor layer and a second multi quantum well structure made from an i-type semiconductor layer in which no impurity is intentionally doped. The second multi quantum well structure is disposed on the first cladding layer. The first multi quantum well structure is disposed on the second multi quantum well structure. The second cladding layer is disposed on the first multi quantum well structure.

Abstract: An optical system includes modulators positioned on a base. Each modulator includes a modulator waveguide that receives a light signal and guides the received light signal through the modulator. The system also includes drive electronics in electrical communication with the modulators. The drive electronics apply electrical energy to each of the modulators such that an electrical field is generated within the modulator waveguide so as to modulate one of the light signals into a modulated signal. The system includes multiple drive paths that each has a length from a contact pad on the drive electronics to a location where the electrical field is formed in one of the modulator waveguides. The modulators are configured such that the drive path length for each of the modulators is less than 0.5 mm.

Abstract: An optical system includes modulators positioned on a base. Each modulator includes a modulator waveguide that receives a light signal and guides the received light signal through the modulator. The system also includes drive electronics in electrical communication with the modulators. The drive electronics apply electrical energy to each of the modulators such that an electrical field is generated within the modulator waveguide so as to modulate one of the light signals into a modulated signal. The system includes multiple drive paths that each has a length from a contact pad on the drive electronics to a location where the electrical field is formed in one of the modulator waveguides. The modulators are configured such that the drive path length for each of the modulators is less than 0.5 mm.

Abstract: A light control device with a reduced electric loss is provided which can suppress a phenomenon of electrically reflecting a high-frequency signal even when it employs a dielectric anisotropic substrate. A light control device includes a signal electrode formed on a dielectric anisotropic substrate and ground electrodes disposed with the signal electrode interposed therebetween. Here, the signal electrode includes at least two signal electrode portions disposed in directions in which the dielectric constant of the substrate is different from each other and a curved connecting portion connecting the at least two signal electrode portions. The connecting portion is configured so that the characteristic impedance in parts connected to the at least two signal electrode portions is equal to that of the corresponding signal electrode portion, and the characteristic impedance in the connecting portion between the at least two signal electrode portions continuously varies.

Abstract: A silicon-based optical modulator exhibiting improved modulation efficiency and control of “chirp” (i.e., time-varying optical phase) is provided by separately biasing a selected, first region of the modulating device (e.g., the polysilicon region, defined as the common node). In particular, the common node is biased to shift the voltage swing of the silicon-based optical modulator into its accumulation region, which exhibits a larger change in phase as a function of applied voltage (larger OMA) and improved extinction ratio. The response in the accumulation region is also relatively linear, allowing for the chirp to be more easily controlled. The electrical modulation input signal (and its inverse) are applied as separate inputs to the second region (e.g., the SOI region) of each arm of the modulator.

Abstract: An optical device includes an active component on a base. The active component is a light sensor and/or a light modulator. The active component is configured to guide a light signal through a ridge of an active medium extending upwards from slab regions of the active medium. The slab regions are on opposing sides of the ridge. The active medium includes a doped region that extends into a lateral side of the ridge and also into one of the slab regions. The depth that the doped region extends into the slab region is further than the depth that the doped region extends into the ridge.

Abstract: An optical coherent transceiver comprising a polarization and phase-diversity coherent receiver and a polarization and phase-diversity modulator on the same substrate interfaced by three grating couplers, on grating coupler coupling in a signal, one grating coupler coupling in a laser signal, and a third grating coupler coupling out a modulated signal.

Abstract: In an optical semiconductor device related to the present invention, a first light source outputting light having a first polarization, a second light source outputting light having a second polarization, a first optical modulator being optically connected to an output side of the first light source and modulating the light that is output from the first light source to output a light signal, a second optical modulator being optically connected to an output side of the second light source and modulating the light that is output from the second light source to output a light signal, and an optical multiplexer coupling the light signal that is output from the first optical modulator with the light signal that is output from the second optical modulator to output a coupled light signal, are integrated on a semiconductor substrate together.

Abstract: A digital integrated optical modulator, in particular for a fiber optical signal transmission or measuring device, having two waveguide arms and electrodes that are arranged along both waveguide arms in or on an optical substrate, wherein the arrangements of the electrodes along the two waveguide arms are different from each other.

Abstract: Included is an apparatus comprising a first circuit component comprising a plurality of optical devices each having an optical input port and an optical output port. All of the optical input ports and all of the optical output ports are positioned on a first side of the circuit component. Also included is a circuit component comprising a plurality of optical devices. The circuit component further comprises a plurality of electrical inputs coupled to the optical devices and positioned on a first side of the circuit component. The circuit component also comprises a plurality of optical input ports coupled to the optical devices and positioned on a second side of the circuit component that does not share any edges with the first side.

Abstract: An electro-optic device 200 comprising a substrate in which first and second waveguides 202, 203 are formed. The device also comprises first and second electrodes 204, 205 comprising an optically transparent conductive material and including primary portions 204a, 205a overlying the first and second waveguides 202, 203 for electrically biasing the first and second waveguides. The device is configured such that one of the first and second electrodes includes one other portion 204b, 205b arranged alongside the primary portion 204a, 205a of the other of the first and second electrodes. This arrangement improves the electro-optic efficiency of the device without the need for a buffer layer in the electrodes.

Abstract: Provided are a semiconductor optical modulator and a semiconductor Mach-Zehnder optical modulator of high efficiency and high reliability.

Abstract: An electro-optic device, comprising a layer of light-carrying material; and a rib, projecting from the layer of light-carrying material, for guiding optical signals propagating through the device. The layer of light-carrying material comprises a first doped region of a first type extending into the rib, and a second doped region of a second, different type extending into the rib such that a pn junction is formed within the rib. The pn junction extends substantially parallel to at least two contiguous faces of the rib, resulting in a more efficient device. In addition, a self-aligned fabrication process can be used in order to simplify the fabrication process and increase reliability and yield.

Abstract: Provided is a semiconductor optical device, which has a buried heterostructure structure and is formed in a structure capable of reducing a parasitic capacitance to further improve characteristics thereof, and also provided are an optical transmitter module, an optical transceiver module, and an optical transmission equipment. The semiconductor optical device includes a modulator portion for modulating light input along an emitting direction and radiating the modulated light, the modulator portion including: a mesa-stripe structure, which includes an active layer and extends in the emitting direction; and a buried layer provided adjacent to each side of the mesa-stripe structure, in which a distance between a lower surface of the buried layer and a lower surface of the active layer is 20% or more of a distance between the lower surface and an upper surface of the buried layer.

Abstract: A doping profile for a modulator facilitates rapidly changing the carrier density in a waveguide. The carrier density change causes rapid changes in the index of refraction of the waveguide. Example modulators include a ring modulator and a Mach Zender modulator. A charge reciprocating section may be provided to control the amount of injected charge.