Abstract: A novel electroabsorption modulator based on tuning the Fermi level relative to mid-gap states in a semiconductor. The modulator includes a semiconductor waveguide that has an input port and an output port. Between the input port and the output port is a section of the waveguide that functions as an electroabsorptive region. Adjacent to the electroabsorptive region are electrical contacts. In operation by adjusting voltages on the electrical contacts, the quasi-Fermi level in the electroabsorptive region of the semiconductor waveguide is brought above or below mid band-gap electronic states. As these states transition between occupancy and vacancy, the absorption coefficient for optical radiation in the electroabsorptive region of the semiconductor changes.

Abstract: A polarization-tracking device having a waveguide grating that serves as a polarization splitter and an optical fiber-to-waveguide coupler. The polarization-tracking device also has an optical mixing circuit configured to receive light from the waveguide grating and a control circuit for tuning the optical mixing circuit. Based on an optical feedback signal received from the optical mixing circuit, the control circuit can configure the latter to produce two optical output signals that represent, e.g., two independently modulated polarization components of a polarization-multiplexed optical input signal or two principal states of polarization of an optical input signal that has been subjected to polarization-mode dispersion. Certain embodiments of the polarization-tracking device lend themselves to convenient implementation in a photonic integrated circuit and are configurable to provide endless polarization control.

Abstract: A system for integrated power combiners is disclosed and may include receiving optical signals in input optical waveguides and phase-modulating the signals to configure a phase offset between signals received at a first optical coupler, where the first optical coupler may generate output signals having substantially equal optical powers. Output signals of the first optical coupler may be phase-modulated to configure a phase offset between signals received at a second optical coupler, which may generate an output signal having an optical power of essentially zero and a second output signal having a maximized optical power. Optical signals received by the input optical waveguides may be generated utilizing a polarization-splitting grating coupler to enable polarization-insensitive combining of optical signals. Optical power may be monitored using optical detectors. The monitoring of optical power may be used to determine a desired phase offset between the signals received at the first optical coupler.

Abstract: A focus enhancing electromagnetic wave propagating device includes a main body formed with a main wave-propagating structure (MS) for focusing an electromagnetic wave into a focusing light spot, and an auxiliary wave-propagating channel (AC) for allowing the wave to propagate toward the focusing light spot. A phase difference is present between the wave after traveling through the MS at its exit end and the wave after traveling through the AC at its exit opening, such that constructive interference is generated at the focusing light spot therebetween. The required phase difference is a function of a distance between the focusing light spot and the exit end of the MS, a distance between the focusing light spot and the exit opening of the AC, velocities of the wave after traveling through each of the MS and the AC, and angular frequencies of the wave after traveling through each of the MS and the AC.

Abstract: In an optical modulator, lights that have been branched by an input optical branching section are input via curved waveguides to a plurality of optical modulation sections arranged in parallel on the same substrate. In the optical modulation sections, optical branching sections of an MZ type optical waveguide are arranged shifted to an output side in the longitudinal direction (x direction) of the substrate, corresponding to an arrangement of input ends of signal electrodes. As a result, even if the input ends of the signal electrodes of the respective optical modulation sections are arranged side by side with a predetermined spacing on one side face of the substrate, input light can be applied to the respective optical modulation sections at low loss, without incurring an increase in the drive voltage.

Abstract: A system and method for producing an 8-QAM-modulated signal are disclosed. The methodology, in an exemplary expedient, generally comprises splitting light from a CW laser into two parts; modulating the first part with a first signal and modulating the second part with a second signal; phase shifting the modulated second part by about ?/4; combining the modulated first part with the phase shifted and modulated second part to produce a four-level modulated signal; and phase modulating the four-level modulated signal with a third signal with a phase modulation of (0, ?/2). Several variations of this method are described herein.

Abstract: A hermetically packaged integrated optical circuit includes an integrated optical circuit and a hermetically sealed container, which defines a volume. The integrated optical circuit is secured within the volume. The hermetically packaged integrated optical circuit further includes a fill gas comprising oxygen disposed within the volume of the hermetically sealed container.

Abstract: A system and method for producing a 16-QAM-modulated signal are disclosed. The methodology, in an exemplary expedient, generally comprises splitting light from a CW laser into two parts; modulating the first part with a first signal and modulating the second part with a second signal; phase shifting the modulated second part by about ?/2; combining the modulated first part with the phase shifted and modulated second part to produce a four-level modulated signal; phase modulating the four-level modulated signal with a third signal with a phase modulation of about (0, ?/2) to produce an 8-QAM-modulated signal, and thereafter modulating that signal with a fourth signal with a phase-modulation of about (0, ?) to produce the 16-QAM-modulated signal.

Abstract: An RF signal processing device which includes a countermeasure set connected to the processing device. The RF signal processing device shifts an incoming RF signal by ninety degrees and combines the phase shifted RF signal with RF jamming signals from a jammer. The processing device next transmits the RF signal including the RF jamming signals from the jammer.

Abstract: A silicon based optical modulator apparatus can include a lateral slab on an optical waveguide, the lateral slab protruding beyond side walls of the optical waveguide so that a portion of the optical waveguide protrudes from the lateral slab towards a substrate.

Abstract: A Mach-Zehnder interferometer type optical modulator includes a first end facet and a reflecting portion opposing the first end facet; a single optical coupler including input and output ports, the optical coupler being disposed between the first end facet and the reflecting portion; first and second optical waveguides that are connected to the input ports of the optical coupler; third and fourth optical waveguides that are connected to the output ports of the optical coupler; and a phase shifting section disposed between the optical coupler and the reflecting portion. The phase shifting section includes a first optical waveguide structure constituting part of the third optical waveguide; a first upper electrode on the first optical waveguide structure; a second optical waveguide structure constituting part of the fourth optical waveguide; and a second upper electrode on the second optical waveguide structure.

Abstract: The objects of the present invention are to shorten a cavity length of an optoelectronic oscillator and to integrate on a semiconductor or SiO2-substrate. An optoelectronic oscillator 10 have an optoelectronic loop comprising a semiconductor laser 11, an optical waveguide 12 guiding laser light emitted from the semiconductor laser, a photodetector 13 detecting laser light guided by the optical waveguide and outputting an electrical signal, an amplifier 14 amplifying the electrical signal outputted from the photodetector, generating an amplified signal and formed on a semiconductor substrate 15. Laser light emitted from the semiconductor laser 11 is controlled by generated amplified signal and it oscillates with a fundamental oscillation frequency determined by a delay time of carrier in the optoelectronic loop circuit or one of the high harmonic components of integral multiples of a fundamental oscillation frequency.

Abstract: A Mach-Zehnder interferometer type optical modulator includes first and third optical waveguides; input and output optical couplers; and a phase shifting section disposed between the input and output optical couplers. The phase shifting section includes first and second optical waveguide structures each including an n-type semiconductor section, a core layer and a cladding layer. The cladding layer of the first optical waveguide structure includes a first section disposed on the core layer, and second and third sections disposed on the first section. The second and third sections are juxtaposed to each other in a direction that intersects a waveguiding direction. The first and second sections are composed of a p-type semiconductor, and the third section is composed of an undoped semiconductor.

Abstract: A transmitter apparatus (2) is described that comprises one or more lasers (4), modulation means (10) to intensity modulate radiation output by each of said one or more lasers (4), and output means for outputting the modulated radiation produced by the modulation means into, for example, an optical fiber (22). The apparatus comprises hollow core optical waveguides (20) formed in a substrate (18) which, in use, guide radiation from the one or more lasers (4) to the modulation means (10) and from the modulation means (10) to the output means. An associated receiver apparatus (30) is also described that comprises one or more detectors (32) and one or more optical fiber attachment means, the one or more optical fiber attachment means being arranged to receive one or more one optical fibers (42). The receiver is characterized in that radiation is guided from the one or more optical fibers (42) to the one or more detectors (32) by at least one hollow core optical waveguide (40) formed in a substrate.

Abstract: An optical modulator having a high stability is provided. In the optical modulator according to the present invention, a phase modulation by an electro-optic effect is made on an optical substrate of an electro-optic material while the setting of an operating point by a thermal-optic effect is made on a planar lightwave circuit (PLC) substrate of quartz, silicon, or the like. Such configuration can suppress the influence of thermal drift or the like because no heat is applied directly to the optical substrate of the electro-optic material. In addition, breakage and warpage of the substrate due to heat are also mitigated. Further, quartz used for the PLC has a low thermal conductivity, approximately one-fifth of that of the LN substrate (approximately 1 W/(m·K)), and therefore, a desired phase difference can be maintained with a low power consumption, and thus, the operating point becomes stabilized.

Abstract: A planar waveguide circuit comprises a first optical splitter to receive an input optical signal, a second optical splitter to receive a reference optical signal, a first optical signal combiner, and a second optical signal combiner. First and second optical waveguides are provided to couple first and second outputs of the first optical splitter to respective inputs of the first and second optical signal combiners. Third and fourth optical waveguides are provided to couple first and second outputs of the second optical splitter to respective inputs of the first and second optical signal combiners. A phase-shifter is provided located to affect the phase of an optical signal propagating in one of the third and fourth optical waveguides. The first and second optical splitters and the first and second optical signal combiners are arranged such that the first, second, third and fourth optical waveguides do not intersect one another.

Abstract: A Mach-Zehnder type optical modulator includes an optical waveguide formed in an electro-optical substrate, an input section that inputs light to the optical waveguide, a plurality of branch modulation sections that generate branched input light, extend from the input section and modulate the branched input light, an interference photocoupler including a plurality of input ports and a plurality of output ports, the input ports being coupled to the branch modulation sections, and an output photocoupler including a plurality of input ports coupled to the output ports of the interference photocoupler and also including a plurality of output ports.

Abstract: An optical frequency COM generator generating an optical frequency COM having flat spectrum characteristics using a single modulator. The optical frequency COM generator has a drive signal system (11) and a bias signal system (14) which drive a first drive signal (9), a second drive signal (10) and bias signals (12, 13) to satisfy the following expression (I). ?A+??=?/2 (I). (where, ?A and ?? are defined as ?A?(A1?A2)/2 and ???(?1??2)/2, respectively, A1 and A2 represent the amplitudes of the first and second drive signals when they are inputted to the electrodes of the first and second drive signals, respectively, and ?1 and ?2 represent the phases of bias voltages applied to first and second waveguides, respectively.

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 (with one segment on each arm, driven by the same input signal), 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: The present invention provides a device is provided for use with a first through fourth light beams. The device includes a first through fourth waveguides and first through fourth light scattering portions. The first waveguide has a length and a width and is arranged to receive the first light beam, wherein the length is larger than the width. The second waveguide is parallel with the first waveguide and is arranged to receive the second light beam. The third waveguide is disposed perpendicularly to and intersecting with the first waveguide and the second waveguide. The third waveguide is arranged to receive the third light beam. The fourth waveguide is parallel with the third waveguide and is disposed perpendicularly to and intersecting with the first waveguide and the second waveguide. The fourth waveguide is arranged to receive the fourth light beam. The first light scattering portion is disposed at the intersection of the first waveguide and the third waveguide.

Abstract: This invention provides a versatile unit cell as well as programmable and reconfigurable optical signal processors (such as optical-domain RF filters) that are constructed from arrays of those unit cells interconnected by optical waveguides. Each unit cell comprises an optical microdisk, an optical phase shifter, and at least one input/output optical waveguide, wherein the microdisk and the phase shifter are both optically connected to a common waveguide.

Abstract: A phase modulation waveguide structure includes one of a semiconductor and a semiconductor-on-insulator substrate, a doped semiconductor layer formed over the one of a semiconductor and a semiconductor-on-insulator substrate, the doped semiconductor portion including a waveguide rib protruding from a surface thereof not in contact with the one of a semiconductor and a semiconductor-on-insulator substrate, and an electrical contact on top of the waveguide rib. The electrical contact is formed of a material with an optical refractive index close to that of a surrounding oxide layer that surrounds the waveguide rib and the electrical contact and lower than the optical refractive index of the doped semiconductor layer. During propagation of an optical mode within the waveguide structure, the electrical contact isolates the optical mode between the doped semiconductor layer and a metal electrode contact on top of the electrical contact.

Abstract: An optical resonator configured to be tuned using a charge-based memory cell includes an optical cavity configured to transmit light and receive injected charge carriers; a charge-based memory cell in proximity to or within the optical cavity, the memory cell containing a number of trapped charges which influence the resonant optical frequency of the optical resonator. A method of tuning an optical resonator includes applying a voltage or current to a charge-based memory cell to generate a non-volatile charge within the memory cell, the nonvolatile charge changing a resonant frequency of the optical resonator.

Abstract: Embodiments of the present invention provide for enhanced monitoring of optical signal characteristics of an optical signal propagating in a signal channel of a photonic integrated circuit. The optical signal characteristics can be obtained with minimal signal loss in the optical signal path and reduced RF crosstalk, while the electrostatic discharge threshold for the photonic integrated circuit is increased, due to the inclusion of a second electro-optic element electrically coupled to a first electro-optic element as part of the signal channel.

Abstract: A mach-zehnder optical modulator includes a substrate having electrooptical effect, wherein: the substrate has an inputting waveguide portion, two intermediate waveguide portions, an outputting waveguide portion and a sub optical waveguide portion, the inputting waveguide portion being branched and coupled to the two intermediate waveguide portions, the two intermediate waveguide portions being combined and coupled to the outputting waveguide portion, the sub optical waveguide being provided on at least one side of the outputting optical waveguide portion and having a given distance from the outputting optical waveguide portion, the sub optical waveguide portion guiding an off-light emitted from a combining portion of the two intermediate waveguide portions; and a width of a starting point of the sub optical waveguide portion is larger than the outputting waveguide portion.

Abstract: Provided is an optical device delaying light by using negative Goos-Hanchen shift. The optical device includes an optical waveguide adapted to guide and emit an incident light, a first reflection layer disposed at one side of the optical waveguide, and a second reflection layer disposed at the other side of the optical waveguide. At least one of the first and the second reflection layers is made of a material having characteristics of negative Goos-Hanchen shift.

Abstract: An optical modulator comprises a bulk-silicon substrate comprising a trench having a predetermined width and a predetermined depth. A bottom cladding layer is formed in the trench, and a plurality of waveguides and a phase modulation unit are formed on the bottom cladding layer. A top cladding layer is formed on the plurality of waveguides and the phase modulation unit.

Abstract: In an optical modulation device, an inverter inverts power of a modulation signal light and generates the inverted modulation signal light. A first nonlinear medium phase-modulates a modulated light by a nonlinear optical effect of the modulation signal light. A second nonlinear medium phase-modulates the modulated light by the nonlinear optical effect of the inverted modulation signal light. An optical interference part controls interference between output light from the first nonlinear medium and that from the second nonlinear medium, and produces the phase-modulated modulated light.

Abstract: An optical device includes a substrate having an electro-optical effect; a main waveguide provided on the substrate; a first Mach-Zehnder part having first waveguides provided on the substrate and coupled with the main waveguide, and first DC electrodes provided between the first waveguides and on the first waveguides and used to generate DC electric fields in the first waveguides; and second Mach-Zehnder parts respectively associated with the first waveguides and comprising second waveguides coupled with each of the first waveguides and second DC electrodes used to generate DC electric fields in the second waveguides, at least one of the second Mach-Zehnder parts being configured to have no second DC electrode provided between the second waveguides and have the second DC electrodes on the second waveguides.

Abstract: A frequency up-conversion system includes an optical splitter, an optical modulator, an optical phase-shifter, and an optical coupler. In one embodiment of the present disclosure, the optical splitter is configured to split an optical wave into a first optical wave and a second optical wave, the optical modulator is configured to modulate the first optical wave to form a modulation wave, the optical phase-shifter is configured to shift the phase of the second optical wave by a predetermined phase to form a shifting wave, and the optical coupler is configured to couple the modulation wave and the shifting wave. In one embodiment of the present disclosure, the optical modulator and the optical phase-shifter are connected in a parallel manner.

Abstract: A communication system capable of employing polarization-dependent phase modulators with a reversing configuration that preserves security against disturbance of a polarization state at a transmission path but without using Faraday mirrors and a communication method using the same are provided. A quantum cryptography system of the present invention includes a first station 1, a transmission path 2, and a second station 3. The first station 1 has means for emitting time-divided optical pulses into the transmission path 2 and measuring a phase difference between the optical pulses returning from the transmission path 2. The transmission path 2 is a medium of light.

Abstract: An optical modulator device comprising an interferometer. The interferometer includes an input optical coupler, an output optical coupler, and two or more controllable optical waveguides located on a substrate. Each controllable optical waveguide connects the input optical coupler to the output optical coupler and has two-state modulator along a segment thereof. The two or more controllable optical waveguides are connected to transmit an output to the output optical coupler, substantially different light amplitudes and/or phases when the two-state modulators of the two controllable optical waveguides are in different states, as driven by data streams having different information content. The two or more controllable optical waveguides are configured to modulate the light amplitudes and/or phases in a substantially same manner when the two-state modulators are in identical states.

Abstract: The invention relates to waveguide optical modulators wherein two or more waveguides are modulated with specific modulation strengths using a single straight signal electrode or a single multi-segment signal electrode. Modulation strengths for each of a plurality of waveguides modulated by a single multi-segment electrode are matched over a wide modulation frequency range. Linearized output characteristics with respect to second and third order distortions arc achieved in one aspect of the invention.

Abstract: An optical apparatus that provides extraordinary light transmission through a sub-wavelength-sized light transmitting region of the apparatus includes a core region of dielectric material having a complex dielectric constant, ?1, surrounded by a metallic cladding material having a complex dielectric constant, ?2, wherein the core region has a maximum dimension, 2a, further wherein 2a is less than ?, where ? is the free-space wavelength of light incident on an input side of the apparatus, and further wherein |?1| is greater than 0.5|?2|, ?1 has a positive real part, and ?2 has a negative real part, whereby the incident light will be transmitted by and exit the apparatus from an output side with extraordinary transmission.

Abstract: A modulator includes an electro-optical substrate and a first and second waveguide formed of a doped semiconductor material positioned on a surface of an electro-optical substrate forming a slot therebetween. A doping level of the semiconductor material being chosen to make the first and second waveguide conductive. A dielectric material is positioned in the slot which increases confinement of both an optical field and an electrical field inside the slot. A refractive index of the semiconductor material and a refractive index of the dielectric material positioned in the slot being chosen to reduce the V?·L product of the modulator.

Abstract: A digital phase modulator for a fiber-optic measurement device. A predetermined total number of electrodes of different lengths are arranged in parallel and on both sides of a light guidance path in or on an optical substrate. The electrodes are arranged in two or more triples along the light guidance path. In each case, two electrodes of successive length within a triple have the same length ratio with respect to one another. Such length ratio is chosen, in particular, to be ?=1.618. The electrode lengths of this triple are chosen such that the smallest step widths of the output value range of the phase modulator can be formed by subtraction between the values of at least two larger electrodes. This allows the resolution of the phase modulator to be increased from 9 bits to 11 bits without change in chip size.

Abstract: A Mach-Zehnder modulator has an optical splitting element splitting an input optical signal into two optical signals that are conveyed by two optical waveguide arms, and an optical combining element combining the two optical signals into an output optical signal. Two traveling wave electrodes (TWEs) carry an electrical modulation signal to induce a change in phase of these two optical signals, and include a number of pairs of modulation electrodes positioned adjacent to the waveguide arms. At least some of the electrodes in one waveguide arm have a different shape (e.g., length or width) than the electrodes in the other waveguide arm to alter the effectiveness of the electrodes in inducing a phase change in the two optical signals.

Abstract: Provided is an electro-optic device. The electro-optic device includes an input Y-branch comprising a first input branch and a second input branch, an output Y-branch comprising a first output branch and a second output branch, a first optical modulator and a second optical modulator connected in series between the first input branch and the first output branch, and a third optical modulator connecting the second input branch to the second output branch. The first optical modulator comprises a PIN diode, and each of the second optical modulator and the third optical modulator comprises a PN diode.

Abstract: According to aspects of embodiments, an optical device includes a first coupler configured to split an optical signal; a second coupler configured to cause optical signals to interfere with each other, a first waveguide configured to couple the first coupler to the second coupler, the first waveguide includes a first phase shifter region having a section narrower in width than an end of the first phase shifter region, the second waveguide includes a second phase shifter region having a section wider in width than an end of the second phase shifter region.

Abstract: A method and system for generating an optical frequency comb that employs a dual parallel modulator that inputs an optical signal at a center frequency of a desired optical frequency comb and an RF signal at a frequency corresponding to a desired spacing of the teeth of the optical frequency comb. The amplitudes of the teeth of the optical frequency comb are controlled by controlling the amplitudes of the two RF inputs to the DPM and the phase shift between the two RF inputs. In some embodiments, the three bias voltages for the three interferometers in the DPM are also controlled. In some embodiments, all three interferometers are all biased at the same point (e.g., quadrature). Preferably, but not necessarily, the three interferometers of the DPM are formed on a single substrate.

Abstract: An optical waveguide device includes; a substrate having an electro-optic effect, and a first optical waveguide and a second optical waveguide formed substantially in parallel on a top face of the substrate. A groove is formed for cutting only the first optical waveguide, of the first optical waveguide and the second optical waveguide. The groove penetrates from the top face to a bottom face of the substrate. Such a groove can be formed for example by fixing a side face of the substrate on the second optical waveguide side to a supporting base of a dicing machine so that the first optical waveguide is positioned on an upper side and the second optical waveguide is positioned on a lower side, and advancing the dicing saw from the bottom face side to the top face side of the substrate.

Abstract: In a multilevel light intensity modulator of the invention, input light is branched into n (n is an integer of 2 or more), and respectively sent to n branching waveguides. On the branching waveguides are respectively provided MZI light modulating sections. The MZI light modulating sections branch the input light into two at a branching ratio different from 0.5:0.5, and respectively output a binary optical signal with a quenching ratio being deteriorated, by on/off driving with a binary electric signal. Then by coupling the light output from the MZI light modulating sections, an optical signal with the light intensity modulated to a 2n value not including the zero level is output. As a result quaternary or higher level light intensity modulation which does not include the zero level, can be realized by a practical configuration using a binary electric signal.

Abstract: It is intended to suppress the influence of a photorefractive phenomenon or the coupling of stray light to signal light. A Mach-Zehnder waveguide type optical modulator is provided which includes a thin plate 1 with a thickness of 20 ?m or less formed of a material having an electro-optical effect, an optical waveguide 2 formed on a front surface or a rear surface of the thin plate, and a modulation electrode modulating light passing through the optical waveguide. The optical waveguide includes an input optical waveguide 21, branched optical waveguides 23 to 28, and an output optical waveguide 30. The branched optical waveguide includes an input branching portion (region B) in which the input optical waveguide is branched into a plurality of optical waveguides, an output merging portion (region D) in which the plurality of optical waveguides connected to the output optical waveguide are merged, and a parallel portion (region C) formed between the input branching portion and the output merging portion.

Abstract: It is an object of the present invention to provide an optical frequency comb generator to generate an optical frequency comb with flat spectral properties using a single modulator. The optical frequency comb generator comprises: a drive signal system (11) and a bias signal system (14) for driving a first drive signal (9), a second drive signals (10), and bias signals (12,13) in accordance with the following Formula (I): ?A±??=?/2??(I) (where ?A and ?? are defined, respectively, as ?A=(A1?A2)/2 and ??=(?1??2)/2, A1 and A2 indicate, respectively, optical phase shift amplitudes guided by the first drive signal and the second drive signal when input into the electrodes, and ?1 and ?2 indicate, respectively, the phases of the bias signals applied to the first waveguide and the second waveguide).

Abstract: A light control element includes three or more silicon thin-film layers (522, 524, 526) placed on a first dielectric layer (521), second dielectric layers (523, 52) placed between the three or more silicon thin-film layers (522, 524, 526), and a third dielectric layer (529) placed to surround the silicon thin-film layers and the second dielectric layers. The three or more silicon thin-film layers are arranged to partially overlap with one anther. In the part where the silicon thin-film layers overlap, the second dielectric layers are placed between the silicon thin-film layers. In the three or more silicon thin-film layers, the silicon thin-film layers adjacent to each other have different conductivity types.

Abstract: An exemplary optical modulator includes an interferometer. The interferometer includes an input optical coupler, an output optical coupler, and two or more controllable optical waveguides. Each controllable optical waveguide connects the input optical coupler to the output optical coupler and has an electro-absorption modulator along a segment thereof. Two of the controllable optical waveguides are connected to transmit to an output of the output optical coupler light of substantially different maximum amplitude.

Abstract: An optical modulator, including: a substrate; an optical waveguide embedded in the substrate; a traveling wave electrode mounted on the substrate and having a traveling wave applied thereon so that a light wave is modulated by the traveling wave with an electro-optic effect. The traveling wave electrode includes a center electrode and ground electrodes; in which the optical waveguide has a plurality of interaction optical waveguides that form a Mach-Zehnder optical waveguide that modulates the light wave in a phase modulation manner when the traveling wave is applied to the traveling wave electrode, the interaction optical waveguides form a region where respective widths of the interaction optical waveguides are different from each other, and the center electrode and the ground electrodes are positioned such that interaction efficiencies between the high frequency electric signal and the light wave guided in the respective interaction optical waveguides are substantially equal to each other.

Abstract: Optical signal processor (1) comprising an optical waveguide loop (3), and first and second phase modulator loops (6, 7), each of the first and second phase modulator loops is in optical communication with the optical waveguide loop, and the first and second phase modulator loops each comprises a respective control signal input port (8, 9) to control phase modulation applied by the phase modulation loops, and the optical waveguide loop comprising two input ports (20a, 20b) to direct input signals (10, 11) in opposite senses in the optical waveguide loop and further comprising an output port (20c) to output resulting signals. The first and second phase modulator loops may comprise nonlinear optical loop mirrors. The processor may be an optical logic gate device.

Abstract: A light control element is provided with a thin board having electro-optical effects; an optical waveguide formed on the thin board; and a control electrode for controlling light that passes through the optical waveguide. The light control element performs speed matching between a microwave signal applied to the control electrode and the light, impedance matching of the microwaves, reduction of a driving voltage and high speed operation. In the control electrode of the light control element, a signal electrode and a grounding electrode are arranged on an upper side of the thin board, and on a lower side of the thin board, a second electrode including the grounding electrode is arranged. The second electrode is arranged not to exist below the signal electrode, especially for achieving impedance matching.

Abstract: The optical phase modulator of the present invention comprises: a main Mach-Zehnder interferometer having first and second main optical waveguide path arms, and whose initial phase difference in the used wavelength is ?; a first sub Mach-Zehnder interferometer having first and second sub optical waveguide path arms that are formed in said first main optical waveguide path arm, and whose initial phase difference in the used wavelength is 0; and a second sub Mach-Zehnder interferometer having third and fourth sub optical waveguide path arms that are formed in said second main optical waveguide path arm, and whose initial phase difference in the used wavelength is 0.