Abstract: A structure for effecting a transition from a passive waveguide to an active waveguide or from an active waveguide to a passive waveguide of the present invention. The inventive device comprises a first cladding; a first core disposed within the first cladding; and a ground plane disposed over the first cladding and the core. A second cladding is disposed on the ground plane. A second core is disposed on the second cladding. A third cladding is disposed on the second cladding and the second core and an electrode is disposed on top of the third cladding. The inventive structure enables the construction of a novel an advantageous switch comprising an input port; an output port; and plural waveguides disposed between the input port and the output port. Each waveguide includes a first cladding; a first core disposed within the first cladding; and a ground plane disposed over the first cladding and the core. A second cladding is disposed on the ground plane. A second core is disposed on the second cladding.

Abstract: An optical switch has a slab waveguide for eliminating polarization dependency between a TE mode optical signal component and a TM mode optical signal component. Disposed on one end of the waveguide is a first deflection portion formed of electro-optical crystal and disposed on the other end of the waveguide is a second deflection portion also formed of electro-optical crystal, in which a half waveplate is disposed at a substantially center portion between the two ends of the slab waveguide. The optical signal propagated from the first deflection portion to the second deflection portion has a TE mode component and a TM mode component thereof switched with respect to each other by the half waveplate.

Abstract: A method for forming two conductive films isolated electrically from each other on the surface of a fiber is provided. According to the method, a fiber is attached into the grooves on a silicon substrate using photoresist as glue. A photoresist pattern for a conductive film on the surface of the fiber is formed by a photolithography process. After wet-etching some amount of the fiber on the patterned area, which is needed for lifting off a metal film deposited on the unnecessary area, a metal film is deposited over whole area of the wafer. Removing photo-resist by a heated stripper solution leaves a metal film only on the patterned area of the fiber and detaches the fibers from the grooves of the wafer The second metal film on the other side of the fiber can be formed by the same procedures as the first metal film except that the deposited surface of the fiber must be attached to the grooves upside down.

Abstract: The present invention relates to nonlinear optical (NLO) materials, compositions thereof and NLO devices using polymeric matrices supporting a second order NLO material defined by the formula ED—B—EW  (I) where ED is an electron donating moiety, B is a bridging moiety, and EW is the electron withdrawing moiety (terminal acceptor group) defined by formula II, where C1 is a carbon atom linked through a double bond to a cyclic or an acylic carbon atom in the bridging moiety, and A1, A2, A3 or A4are the same or different from one another, each of which is an electron withdrawing group such as CN, COR, COOR, COOH or CH═C(R)2 where R is a C1-6 alkyl.

Abstract: A tunable Fabry-Perot filter is provided with two optical fibers each being coated with a high-reflective thin film at its one end, a silicon block for aligning the two optical fibers with each other having a pair of V-shaped grooves formed at both ends thereof, respectively, a resonant cavity medium of silicon or polymeric material having a high coefficient of thermo-optic effect, and a thermal electrode for applying heat to the resonant cavity medium.

Abstract: Electrically switchable optical elements, such as application specific integrated elements including filters, lenses and switches, are combined with wavelength locked feedback loops. Electrically Switchable Bragg Grating (ESBG) technology is combined with a wavelength locked feedback loop to provide variable focal length optical systems which automatically adjust the focal length of incident light.

Abstract: A self-aligned optical modulator that modulates an input optical signal in order to generate a modulated output optical signal includes an optical modulator device including a waveguide, a first modulating electrode, a second modulating electrode, and a two-dimensional electron (hole) gas (2DEG) proximate the first modulating electrode, the waveguide includes an input port wherein the input optical signal is introduced into the waveguide, an output port wherein the modulated output optical signal exits the waveguide, and a region of modulating propagation constant disposed along a first length of the waveguide and between the input port and the output port, wherein the input optical signal is guided by total internal reflection in the waveguide, and the waveguide is formed at least in part from an active semiconductor. The first modulating electrode is positioned proximate a first surface of the region of modulating propagation constant and electrically separated from an active semiconductor.

Abstract: The waveguide-type optical device comprises a optical transmission element 12, an optical waveguide 20 optically connected to the optical transmission element, and a slab optical waveguide 30 formed of an electrooptic material and optically connected to the optical waveguide 20. In the waveguide-type optical device, a mode field width of the optical waveguide 20 has a value which is between a mode field width of the optical transmission element and a mode field width of the slab optical waveguide, whereby the connection loss between the optical transmission element 12, such as an optical fiber, etc. and the slab optical waveguide 30 can be small.

Abstract: The present invention provides an optical attenuator comprising an optical attenuator module, an optical splitter, a detector and a control unit. Input radiation (Pi) is received at the attenuator module which is operable to attenuate the input radiation to generate corresponding attenuated radiation (Po). The detector is operable to receive a portion of the attenuated radiation (0.1 Po) and generate a corresponding electrical signal T1. The signal T1 is applied by the control unit via a first feedback loop to regulate the attenuator module so that radiation power of the attenuated radiation is maintained to a predetermined level. In a situation where an interruption of the input radiation (Pi) occurs, the control unit is operable to monitor temperature of the attenuator module using a thermistor sensor and to regulate the temperature of the module using a second feedback loop to a predetermined temperature during the interruption.

Abstract: An apparatus and associated method for altering the propagation constant of a region of deflecting propagation constant in an optical waveguide. The method comprising positioning an electrode of an electrode shape proximate the waveguide. A region of deflecting propagation constant is projected into the waveguide and corresponds, in shape, to the electrode shape by applying a voltage to the shaped electrode. The propagation constant of the region of deflecting propagation constant is controlled by varying the voltage that adjusts a deflection angle applied to an input optical signal flowing through the waveguide.

Abstract: An optical modulator has optical channels formed in a waveguide substrate in which two of the waveguide channel branches have reverse polarity relative to each other. In addition, the optical modulator has at least one of the following: 1) an electronic signal electrode and an electronic ground electrode are placed in proximity with opposite faces of the waveguide substrate, 2) a portion of said waveguide substrate is removed to afford a reduced electronic signal refractive index, and 3) the waveguide substrate has a fixing substrate attached to it with the refractive index of the fixing substrate lower than said refractive index of the waveguide substrate.

Abstract: An optical delay generator comprises a first waveguide made from electro-optically active material resonantly coupled to a second non-electro-optically active waveguide. The first waveguide contains a chirped distributed Bragg reflector structure which reflects optical signals at a specific wavelength at a specific reflection point within the structure. An electric field applied to the first waveguide changes the refractive index of the electro-optically active material and thus shifts the reflection point. Optical signals reflecting from the reflection point are resonantly coupled into the second waveguide, and are thus not affected by the electric field applied to the first waveguide. The controllable optical delay applied to the optical signals results from control over the reflection point and the round-trip travel time for an optical signal forward propagating in the first waveguide, being reflected at the reflection point, and backward propagating in the second waveguide.

Abstract: The optical device comprises a first substrate 10 having a control circuit formed on; optical waveguide layer 40 formed above the first substrate and having a refractive index changed by electro-optic effect; and second substrates 14a, 14b having prism electrodes 18 for applying voltages to the optical waveguide layer. The control circuit and the prism electrodes are electrically connected to each other via columnar conductors 20. Even in a case where thermal expansion coefficients of the control substrate and of the light deflection substrates are very different from each other, the pins are flexed corresponding to eternal forces, whereby junction is protected from being damaged in the joining processing. Thus, the optical switch can be highly reliable.

Abstract: This invention discloses a monolithic optical light modulator including a substrate having formed monolithically thereon a modulator and a light detector providing a modulating output to said modulator.

Abstract: An optical intensity modulator for high-speed RZ and NRZ data modulation based on a balanced three-arm Mach-Zehnder interferometer. The three arms are joined at the input and output sides of the device by three-way couplers. The input coupler is structured to couple approximately equal powers into the first and third arms and no more than 50% power into the second arm. In the straight sections of the arms, there is arranged an AC electrode structure for applying an RF modulation signal and a DC electrode structure for biasing the device at a working point. The AC electrode structure is arranged so that an applied modulation signal induces a negative phase shift (−&Dgr;&phgr;) in the first arm in relation to the second arm and a positive phase shift (+&Dgr;&phgr;) in the third arm in relation to the second arm.

Abstract: The invention provides an optical modulator which suppresses the loss of a microwave which advances through an electrode and of light which propagates in a waveguide and makes the losses in individual arm waveguides substantially equal to each other to suppress the deterioration of the extinction coefficient to improve the transmission quality. The optical modulator includes a substrate having an electro-optical effect and having a ridge, first and second grooves and first and second banks formed thereon, a Mach-Zehnder optical waveguide, an electrode, and first and second recesses formed at symmetrical positions with respect to the ridge on the first and second banks, respectively. The optical modulator is applied, for example, to a transmission side apparatus for a long distance optical transmission system.

Abstract: An electro-optic element comprising a ferroelectric substrate comprising a single crystal having an electro-optic effect, in which an optical waveguide is formed by thermal diffusion of titanium in a main face, and in which an axis in which said electro-optic effect is induced is parallel to said main face; a heat treated buffer layer provided on said ferroelectric substrate on a side in which said optical waveguides are formed; electrodes provided on a part of the buffer layer; and a protective film for preventing contamination of the buffer layer provided on at least the region of the buffer layer on which the electrodes are not formed.

Abstract: The invention has improved parameters when compared iwth prior art devices; pump power was decreased by four orders of magnitude and amplification of signal was increased by two orders of magnitude. The main features of the invention are the following. A nonlinear optical waveguide is made on the basis of a layered MQW-type structure, where unidirectional distributively coupled waves (Ip, Is), e.g. coupled waves having orthogonal polarizations, interact. The wavelength of optical radiation is chosen close to the wavelength of resonance in the structure. Input/output elements, taking into account the asymmetry of the cross section of the nonlinear optical waveguide, are mounted at the input and output of the nonlinear waveguide making up a compact nonlinear-optic module. A small electric current is injected across said nonlinear optical waveguide through electrodes, so as to increase the gain and decrease the pump optical power to a high degree.

Abstract: An optical waveguide comprising an MgO substrate 10, and a slab waveguide layer 24 formed on the MgO substrate 10 and including a core layer 18 of a ferroelectric or an antiferroelectric, further comprises a stress alleviating layer 12 which substantially lattice-matches with the MgO substrate and the slab waveguide layer 24 and has an average thermal expansion coefficient in the range of 7.0×10−6-14.0×10−6/° C. at the room temperature to 700° C. Accordingly, the optical waveguide device utilizing the magnesium oxide substrate can be formed without breaking the optical waveguide layer and the magnesium oxide substrate itself.

Abstract: A device for optical space switching in optical networks. The optical device comprises a broad area optical waveguide section having a number of electrodes extending over at least a portion of the length of the broad area optical waveguide section. The application of an electrical signal to an electrode causes a local change in effective refractive index of the broad area optical waveguide section, thereby causing light preferentially to propagate along a predetermined path in dependence on the configuration of the electrode. In particular the broad area waveguide device is implemented in indium phosphide (InP).

Abstract: A structure for effecting a transition from a passive waveguide to an active waveguide or from an active waveguide to a passive waveguide of the present invention. The inventive device comprises a first cladding; a first core disposed within the first cladding; and a ground plane disposed over the first cladding and the core. A second cladding is disposed on the ground plane. A second core is disposed on the second cladding. A third cladding is disposed on the second cladding and the second core and an electrode is disposed on top of the third cladding. The inventive structure enables the construction of a novel an advantageous switch comprising an input port; an output port; and plural waveguides disposed between the input port and the output port. Each waveguide includes a first cladding; a first core disposed within the first cladding; and a ground plane disposed over the first cladding and the core. A second cladding is disposed on the ground plane. A second core is disposed on the second cladding.

Abstract: An integrated-optic device comprising a photorefractive substrate, an optical waveguide channel and at least one diffractive Bragg grating integrated in the substrate and intersecting the optical waveguide channel. The diffractive Bragg grating(s) causes at least a fraction of light coupled into the optical waveguide channel to be coupled out of the optical waveguide channel.

Abstract: A lithium niobate-based electro-optic device is formed to include a parylene conformal coating layer, as a sealant against moisture. The use of parylene (preferably, parylene-C) has been found to form an acceptable moisture vapor barrier without the need for additional hermetic packaging of the electro-optic device.

Abstract: This invention discloses a selectably directable optical beam generating device including at least one light source, and at least one substrate, each having formed thereon a multiplicity of waveguides, each waveguide receiving light from the at least one light source and emitting light, the totality of light emitted by the multiplicity of waveguides producing at least one selectably directable output beam.

Abstract: This invention discloses a waveguide filter device including a necked waveguide having a relatively broad input end which receives light and allows propagation of multi-mode light waves therethrough, a narrowed neck portion at which higher modes radiate outside the waveguide and only the modes which can propagate therethrough pass therethrough and a relatively broad output end.

Abstract: The invention relates to a method and a modulator circuit for modulating light in a modulator circuit. The modulator circuit comprises a Mach-Zehnder modulator having at least one optical input and at least one optical output, said Mach-Zehnder modulator modulating light, which is fed to the input of the Mach-Zehnder modulator in response to applied electrical modulation signals from a driver circuit. According to a method of the invention, the applied modulation signal on the electrodes of the Mach-Zehnder modulator is superimposed by a pilot tone which is thus superimposed by the modulated light emitted by the Mach-Zehnder modulator. In response to the emitted modulated light, an electrical feedback circuit generates bias control signals for the bias circuit and driver control signals for the driver circuit for regulating the bias signal and the driver signal fed to the Mach-Zehnder modulator.

Abstract: An electric optical fiber grating has a central wavelength. The central wavelength of an optical fiber grating can be adjusted under strain. The filter includes a bimetal plate, an elastic structure and an solenoid to achieve the goal of switching the central wavelength of an optical fiber grating. Meanwhile, the bimetal plate can also provide proper passive compensation according to the temperature effect around them so that it is not necessary for the optical fiber grating that can switch central wavelengths, to monitor and conduct feedback control at all times. Thus it does not consume power. Therefore, the electric optical fiber grating filter can both achieve the goal of switching central wavelengths and has the advantage of not being sensitive to temperature.

Abstract: A new electro-optic (EO) phase modulator constructed from a combination of a low-loss passive polymer waveguide and a self-assembled chromophore superlattice (SAS) with an intrinsically polar microstructure. In contrast to typical polymer-based modulators, the present invention utilizes a siloxane SA methodology that enables the acentric alignment of constituent chromophores during film growth without the need for post-deposition electric field poling. The guiding layer is constructed of the SAS and the glassy polymer Cyclotene™. The use of SiO2, Cytop™ and Cyclotene™ glassy polymers, results in a straightforward device fabrication process that is compatible with the thermally and photochemically robust SAS. Thus, nanoscale control of the film architecture results in greatly simplified macroscopic device fabrication. The present invention provides a SAS-based electro-optic modulator demonstrating excellent electro-optic response properties and a &pgr; phase shift.

Abstract: The present invention includes a polarization independent optical interconnect device for selectively interconnecting a plurality of optical signals between a plurality of inputs and a plurality of outputs. The present invention may provide advantages typically associated with conventional polarization based switches, including terabit per second data rates and high speed switching, to facilitate use in fiber optic networks. Moreover, the switch of this invention is polarization independent, and therefore, may route either polarized or unpolarized light. Since both the input and output light may be unpolarized, the switch of this invention may have a high light efficiency (i.e. no losses associated with an input polarizer) and minimal insertion losses as compared to typical polarization based switches.

Abstract: This invention discloses an optical device including at least one substrate having formed thereon a multiplicity of electrically controlled waveguides; and a light receiver for directing light into the multiplicity of waveguides, the light receiver comprising a selectable polarization rotator.

Abstract: Active photonic crystal devices for controlling an optical signal is disclosed. The devices include a planar photonic crystal with a defect waveguide. In one embodiment of the invention, the propagation of the optical signal is controlled by changing a dimension of the planar photonic crystal structure. In another embodiment, the propagation of the optical signal is controlled by inserting rods into the columnar holes of the planar photonic crystal structure. In a third embodiment of the invention, the propagation of the optical signal is controlled by filling the holes of the planar photonic crystal structure with fluid.

Abstract: This invention discloses a selectably directable optical beam deflecting device including at least at least one substrate having formed thereon a multiplicity of waveguides, each waveguide receiving light and emitting light, the totality of light emitted by said multiplicity of waveguides producing at least one selectably directable output beam, and at least one multiplexer applying electrical inputs to the at least one substrate for individually controlling the light emitted by each of the multiplicity of waveguides, thereby governing the orientation of the selectably directable output beam.

Abstract: The optical deflector comprises: an optical waveguide 12 of a dielectric material having electrooptical effect; and a pair of electrodes 10, 14 opposed to each other across the optical waveguide, an electric field is applied between the opposed electrodes to change a refractive index of the dielectric material to thereby control a propagating direction of signal light propagating in the optical waveguide 12, wherein the dielectric material has a first refractive index in its initial state, has a second refractive index by application of an electric field of a first polarity, and retains as a third refractive index a refractive index obtained after the electric field has been removed. The dielectric material has the third refractive index has the first refractive index by the application of an electric field of a second polarity different from the first polarity and removal of the electric field.

Abstract: A traveling wave optical modulator includes an optical waveguide substrate made of an electro-optic and ferrodielectric single crystal in the form of an X- or Y-orientation plate_and comprising a thicker portion having a larger thickness and a thinner portion having a smaller thickness; first and second branched optical waveguide portions formed at least on the thinner portion of the optical waveguide substrate; a set of electrodes provided on at least the thinner portion of the substrate and adapted for applying voltage to the first and second optical waveguide portions to modulate a light propagating the optical waveguide portions; and a buffer layer provided to cover a part of the optical waveguide portions at the thinner portion of the substrate, the electrodes crossing on the buffer layer.

Abstract: This invention discloses a method of aligning a multiplicity of waveguides with respect to external optics.

Abstract: A signal coupler is comprised of a transmitting section and a receiving section. The receiving section includes a polymer pyroelectric film element having a greater than 1% by volume of a high thermal diffusivity material, such as aluminum nitride, to improve the thermal diffusivity of the polymer film. A preferred embodiment of the transmitting section includes a thin film resistive heater to generate thermal pulses which are coupled to the receiving section by a thin film of thermal grease disposed between the receiving section and the transmitting section.

Abstract: The present invention relates generally to electro-optically active waveguide segments, and more particularly to the use of a selective voltage input to control the phase, frequency and/or amplitude of a propagating wave in the waveguide. Particular device structures and methods of manufacturing are described herein.

Abstract: An optical modulator includes a substrate having an electrooptic effect, an optical waveguide having first and second cascading portions in the substrate, and transmitting an optical field, a first coplanar strip electrode having a first part over the first cascading portion and second and third parts extending beyond the first cascading portion, wherein the first part is approximately perpendicular to the second and third parts and has a width substantially the same as the first cascading portion, a second coplanar strip electrode having a first part over the second cascading portion and second and third parts to extend beyond the second cascading portion, and the first part being approximately perpendicular to the second and third parts, and a voltage source supplying a voltage to the first coplanar strip electrode, wherein the second coplanar strip electrode is grounded and is symmetrical to the first coplanar strip electrode.

Abstract: An electro-optic modulator is provided which comprises an electro-optic substrate, a Mach-Zehnder Interferometer optical waveguide structure, and at least two electrodes. In an embodiment of the invention, the Mach-Zehnder Interferometer optical waveguide structure has a mode transition section for reducing the optical mode size and bringing the optical mode center closer to the upper surface of the electro-optic substrate. In another embodiment, there is a laterally recessed adhesion layer disposed between the electrodes and the electro-optic substrate. The recess in this adhesion layer minimizes the dissipative effect that the adhesion layer would ordinarily have on the propagation of RF energy along the electrode. In yet another embodiment, a dual drive arrangement is described for driving an electro-optic modulator. Finally, an integrated modulator array is described.

Abstract: An optical waveguide modulator 40 has a substrate 1 made of a material with an electrooptic effect, an optical waveguide 2 to guide a lightwave 2, a travelling wave-type signal electrode 3 and the ground electrodes 4 to control the lightwave. Moreover, it has a buffer layer 6, at least a part thereof being embedded in the superficial layer of the substrate 1, having a larger width “W” than a width “&ohgr;” of the travelling wave-type signal electrode 3 only under the signal electrode 3 and its nearby part.

Abstract: A flat panel display is based on a new switching technology for routing laser light among a set of optical waveguides and coupling that light toward the viewer. The switching technology is based on poled electro-optical structures. The display technology is versatile enough to cover application areas spanning the range from miniature high resolution computer displays to large screen displays for high definition television formats. The invention combines the high brightness and power efficiency inherent in visible semiconductor diode laser sources with a new waveguide electro-optical switching technology to form a dense two-dimensional addressable array of high brightness light emissive pixels.

Abstract: An optical modulator (20) that operates as a phase modulator at high frequency and as a frequency modulator at low frequencies to provide a suitable signal-to-noise ratio over a wide frequency band. The modulator (20) includes an optical waveguide 120 and opposing RF electrodes (122, 124) formed in the waveguide (120). An RF input signal is applied to the electrodes (122, 124) to create an electric field that changes the index of refraction of the waveguide (120) to affect the propagation speed of an optical carrier signal (126), and thus provide the modulation. The electrodes (122, 124) are long velocity-matched electrodes that provide the RF loss versus RF frequency needed to produce the desired V&pgr; versus RF frequency over the entire bandwidth. The lower V&pgr; at lower RF frequencies will emphasize the lower frequencies and improve the low-frequency fidelity of the optical link by boosting the low-frequency signals above the excess link noise generated in the demodulator (12).

Abstract: This invention discloses a selectably directable optical beam deflecting device including at least at least one substrate having formed thereon a multiplicity of waveguides, each waveguide receiving light and emitting light, the totality of light emitted by said multiplicity of waveguides producing at least one delectably directable output beam, and at least one multiplexer applying electrical inputs to the at least one substrate for individually controlling the light emitted by each of the multiplicity of waveguides, thereby governing the orientation of the selectably directable output beam.

Abstract: An apparatus for interfacing optical signals to an optical fiber has a layered interface element with a first electrically conductive layer defining a first surface, a photoactive material layer in intimate contact with the first layer on a second surface opposite the first surface, a second electrically conductive layer in intimate contact with the photoactive material layer, confining the photoactive material layer between the first and second electrically conductive layers, and a third surface angularly disposed to the first surface and intersecting the photoactive material layer; and a pressure element having a contact surface translatable toward the first surface of the interface element, to urge an optical fiber positioned across the interface element into the first surface, and by local deformation of the optical fiber also into the third surface, creating thereby an intimate contact region between an edge of the photoactive layer intersecting the third surface and the optical fiber.

Abstract: An apparatus and associated method for altering the propagation constant of a region of filtering propagation constant in an optical waveguide. The method comprising positioning an electrode of an electrode shape proximate the waveguide. An altered region of filtering propagation constant is projected into the waveguide that corresponds, in shape, to the electrode shape by applying a voltage to the shaped electrode. The propagation constant of the region of filtering propagation constant is controlled by varying the voltage. Such filter embodiments as an Infinite Impulse Response filter and a Finite Impulse Response filter may be provided.

Abstract: An apparatus and associated method for altering the propagation constant of a region of deflecting propagation constant in an optical waveguide. The method comprising positioning an electrode of an electrode shape proximate the waveguide. A region of deflecting propagation constant is projected into the waveguide and corresponds, in shape, to the electrode shape by applying a voltage to the shaped electrode. The propagation constant of the region of deflecting propagation constant is controlled by varying the voltage that adjusts a deflection angle applied to an input optical signal flowing through the waveguide.

Abstract: A self-aligned optical modulator that modulates an input optical signal in order to generate a modulated output optical signal includes an optical modulator device including a waveguide, a first modulating electrode, a second modulating electrode, and a two-dimensional electron (hole) gas (2DEG) proximate the first modulating electrode, the waveguide includes an input port wherein the input optical signal is introduced into the waveguide, an output port wherein the modulated output optical signal exits the waveguide, and a region of modulating propagation constant disposed along a first length of the waveguide and between the input port and the output port, wherein the input optical signal is guided by total internal reflection in the waveguide, and the waveguide is formed at least in part from an active semiconductor. The first modulating electrode is positioned proximate a first surface of the region of modulating propagation constant and electrically separated from an active semiconductor.

Abstract: This invention discloses an optical waveguide-lens including at least one substrate having formed thereon a multiplicity of electrically controlled, phase-shifting waveguides and an electrical control signal source providing electrical signals to said multiplicity of waveguides to cause them to have a desired lens functionality.

Abstract: A directional optical coupler is shown and described, which includes an optical cell that is made of a first transparent conductor, a second transparent conductor and an electro-optical member interposed between the two transparent conductors, the electro-optical member having an index of refraction which can be varied only along one crystal axis by application of an electric field.

Abstract: The present invention relates to a method and a device for modulating optical signals based on modulating bending losses in bend, quantum well semiconductor waveguide sections. The complex refractive index of the optical active semiconducting components of the waveguide section is modulated by applying a variable electric or electromagnetic field. The modulation of the complex refractive index results in a modulation of the refractive index contrast and the absorption coefficient for the waveguide at the frequency of the light. By carefully adjusting the composition of the semiconducting components and the applied electric field in relation to the frequency of the modulated radiation, the bending losses (and possibly coupling losses) will provide extinction of light guided by the bent waveguide section. The refractive index contrast may be modulated while keeping the absorption coefficient substantially constant and small, whereby the guided light can be modulated only by bending losses.