Abstract: The present invention relates to an electrochronic element including the following elements: an electrode (E1), an electrochromic functional layer (FS), an ion-conducting electrolyte (EY) a layer with high electrical charge capacity (SK), a counter-electrode (E2), the electrochromic functional layer (FS) being a nanoporous doped semiconductor layer having structure sizes smaller than 50 nm.

Abstract: An optical modulator drive circuit provides a different approach to driving an optical modulator than presently employed, resulting in a reduction in power dissipation of the drive circuit by as much as 80%. Therefore, this invention dissipates as little as 20% of power of the present drive circuits known in the art. The optical modulator may be a semiconductor electro-absorption modulator but the principle of the invention can be applied any other type of electro-optic modulator that relies on a voltage to modulate an optical signal.

Abstract: This invention relates to a semiconductor device and method for switching or modulating optical signals. The semiconductor device has a photodetector having a low electrical capacitance Cd, a detector absorbing layer for absorbing an optical signal beam, a modulator having a low capacitance Cm and a modulator absorbing layer exhibiting an electric field-dependent absorption coefficient. The modulator absorbing layer is used for absorbing an optical power beam, which is to be modulated or switched. The device has a low resistivity region between the photodetector and the modulator such that the electric field-dependent absorption coefficient is altered uniformly and rapidly throughout the modulator absorbing layer during absorption of the optical signal beam in the detector absorbing layer. The device is equipped with a high resistivity element in series with the low resistivity region for minimizing a net charge flow to and from the device.

Abstract: An exemplary monolithic stabilized monolithic transmissive active optical device, such as an electroabsorption modulator (EAM), a variable optical attenuator (VOA), or a semiconductor optical amplifier (SOA), with an output optical tap, includes: a substrate; a waveguide layer; a semiconductor layer. The waveguide layer is coupled to the substrate and includes an active medium, which interacts with a predetermined wavelength of light, and is responsive to an electric signal. The electric signal is applied between the substrate and the semiconductor layer. The waveguide layer includes an output optical tap section and an active section adjacent to the output optical tap section. These sections include portions of the active medium. Further embodiments of the present invention incorporate temperature as well as bias control to improve performance of exemplary monolithic transmissive active optical devices. Additional embodiments include exemplary methods of manufacture and methods of operation.

Abstract: There is provided an optical modulator in which positive holes produced in the valence band are not piled up, the electrostatic capacity can be decreased, the frequency response characteristic is improved, and which is capable of operating at a high speed. In an optical modulator comprising: an n-type clad layer; a stripe-like modulation layer elongated in the direction of light propagation and formed on the top surface of the n-type clad layer; a buffer layer formed on the top surface of the modulation layer; and a p-type clad layer formed on the top surface of the buffer layer, the buffer layer has its composition the band gap energy of which is higher by an energy due to a p-type acceptor level than that of the modulation layer, thereby to remove a difference in band gap energy between the modulation layer and the buffer layer.

Abstract: Provided is a micro-electromechanical assembly including an out-of-plane device formed on a device layer of a single crystal silicon substrate. A ribbon structure is formed on the device layer, where the ribbon structure has at least one of a width or depth, which is less than the width or depth of the out-of-plane device. A connection interface provides a connection point between a first end of the out-of-plane device and a first end of a ribbon structure, wherein the ribbon structure and out-of-plane device are integrated as a single piece.

Abstract: The optical domain optical signal sampling device is for sampling an optical signal-under-test and comprises a semiconductor saturable absorber, an optical sampling pulse source, an optical signal input and a light detector. The optical sampling pulse source is arranged to illuminate the semiconductor saturable absorber with optical sampling pulses. The optical signal input is arranged to illuminate the semiconductor saturable absorber with the optical signal-under-test. The light detector is arranged to receive optical samples of the optical signal-under-test output by the semiconductor saturable absorber in response to the optical sampling pulses.

Abstract: The present invention provides a device, a method of making the device, and a system incorporating the same. In one embodiment, the device includes a substrate that has first and second opposing surfaces and first and second thicknesses, wherein the second thickness is less than the first thickness, and the first surface is substantially planar. The device further includes a conductive trace having an input end and an output end and located over the first surface of the substrate, wherein at least one of the input end or output end is aligned with the second substrate thickness.

Abstract: An optical device including a substrate, a distributed feedback (DFB) semiconductor laser formed on the substrate and including a diffraction grating having an asymmetrical &lgr;/4 phase shift region, the diffraction grating extending along an optical axis of the DFB semiconductor laser, and a field absorbing modulator integrated with the DFB semiconductor laser on the substrate for modulating a light wave emitted from the DFB semiconductor laser, the optical modulator having a facet reflection rate between 0.01 and 0.02% at an output end thereof, the diffraction grating having a &kgr;L value between 1 and 1.2. The proper combinations of the &kgr;L value of the diffraction grating and the reflection rate of the output facet of the modulator of the DFB semiconductor laser can fabricate the source for integrating the modulator having the excellent quality with a higher yield and lower cost.

Abstract: An optical device includes a grounded base and an optical modulator chip having a top surface, a back surface and side surfaces. The optical modulator chip is positioned on the grounded base with the back surface facing the grounded base. The optical modulator chip includes a first ground electrode, a signal electrode and a second ground electrode located over the top surface of the optical modulator chip. The first and second ground electrodes of the optical modulator chip are interconnected with resistive layers on a surface of the optical modulator chip.

Abstract: The present invention uses quantum interference of one and two photon absorption from a multiple color fields to optically inject ballistic spin currents in unbiased photoconductors. The spin currents can be generated with and without an accompanying electrical current and can be controlled using the relative phase of the colors. In one aspect of the there is provided a method of generating spin currents in a photoconductor material comprising producing a first coherent light beam having a first frequency &ohgr;1 and a second coherent light beam having a frequency twice the first frequency 2&ohgr;1, polarizing the first and second coherent light beams to have a preselected polarization with respect to each other, and simultaneously irradiating a selected region of the photoconductor material with the first coherent light beam and the second coherent light beam to generate a spin current in the photoconductor.

Abstract: A micro-mechanical optical modulator having a movable membrane that is spaced from a multi-layer mirror that is disposed on a substrate. The multi-layer mirror includes an anti-reflection layer that is disposed on the substrate, and a coating layer that is disposed on the anti-reflection layer. The combined thickness of the membrane and the coating layer is equal to an integer multiple of one-half of the operating wavelength of the modulator. This thickness restriction is different than prior art Fabry-Perot cavity modulators, which typically independently restrict membrane thickness and coating layer thickness, each to multiples of one quarter of the operating wavelength. By relaxing the requirements imposed by the prior art on layer thickness, modulator performance parameters can be optimized. Specifically, optical bandwidth can be traded for insertion loss and vice versa, as suits the specifics of a particular application.

Abstract: An apparatus and method of fabricating and operating a micro-electromechanical systems (MEMS) integrated optical structure is disclosed. Micro-optics is integrated with MEMS actuators to provide a building block for a micro-optical communication device. Such micro-optical communication device may realize a variety of optical communication systems including optical interconnects, laser communications, or fiber optic switches. In accordance with one aspect of the present invention, a micro-optical element such as a micro-lens is advantageously integrated with an actuator such as MEMS comb drive actuator to form a MEMS lens assembly. The MEMS lens assembly is further coupled to an optical source which may provide a MEMS integrated micro-optical communication device. This integration substantially obviates the generally needed external or manual positioning of the micro-optical element to align a light beam or an optical signal being emitted from the optical source.

Abstract: An improved electro-absorption semiconductor modulator using an external modulation, in which a multi-quantum well (MQW) structure for absorbing a light beam is provided to increase an optical absorption capability according to an electric field, thus increasing an optical power difference between ON and OFF states. Accordingly, the electro-absorption semiconductor modulator includes a semiconductor substrate; a lower cladding layer deposited over the semiconductor substrate; a multi-quantum well (MQW) layer comprised of barrier layers and undoped well layers stacked, in succession, predetermined times on the lower cladding layer, the barrier layers being doped with an impurity; an upper cladding layer deposited over the multi-quantum well layer; and, an ohmic contact layer deposited over the upper cladding layer. The impurity comprises an n-type dopant such as silicon and has a doping density of 1017/cm3.

Abstract: Mach-Zehnder modulator with index tuned multimode interference couplers comprising a substrate, an optical input waveguide on the substrate for receiving a light signal, and an input multimode interference coupler. The input multimode interference coupler splits the received light and propagates it down two separate waveguides. Also, the input multimode interference coupler contains electrodes that allow the index of refraction to be tuned. These waveguides contain phase shift regions so that the light signals can be combined at the output multimode interference coupler out of phase. This allows the modulation of the light signal. Also, the output multimode interference coupler contains electrodes that allow the index of refraction to be tuned. The modulated light signal is then outputted through an output waveguide. The tuning of the index of refraction for the input and output multimode interference couplers eliminates the sensitivity of the areas to variations in their geometry.

Abstract: An optical structure includes a substrate having semiconductor material and a grating structure. The grating structure has the property of emitting at least one frequency band so that light having a frequency from that frequency band cannot propagate in the grating structure. The grating structure has a configuration of pores and a defective region. The pores are disposed outside the defective region in a periodic array, and the periodic array is disturbed in the defective region. A surface of the grating structure is provided with a conductive layer at least in the vicinity of the defective region. A method for producing the optical structure is also provided.

Abstract: A light modulating switch (210) including a switching element (218) having a first portion (226) of electro-optic material to which first and second electrodes (213, 224) are associated. A second portion (228) is composed of material having an index of refraction matching that of the first portion (226) when no voltage is applied to electro-optically activate the first portion (226), but the index of refraction of the second portion (228) is less than the index of refraction of the first portion (226) when the first portion (226) is electro-optically activated by application of voltage to the electrodes (213, 224).

Abstract: A method for enhancing the optical performance of a reflective spatial light modulator by micro-planarizing surfaces within the SLM, such as the reflective surface of each pixel, by gas-cluster-ion-beam bombardment.

Abstract: In the monolithically integrated photonic circuit, light travels through multiple quantum well channel waveguides and is coupled into and out of the devices that reside in common on a single semiconductor substrate. Each device, which is co-planar with any other device on the substrate, is comprised of a quantum well channel waveguide of a pre-determined length and an electrical contact pad mounted on the waveguide that facilitates the application of electric field to the device. The function of any particular device as an optical source, an optical modulator or a photo-detector is determined by the bias mode of electric field applied to that particular device. The circuit is comprised of multiple rows of such devices. Each of these rows contains at least three devices which function as an optical source, an optical modulator and a photo-detector, respectively, and are separated from each other by electrical isolation gaps.

Abstract: A band discontinuity reduction layer having a band gap energy larger than that of that of an MQW (multiple quantum well) absorption layer and smaller than that of a p-InP clad layer is provided between the MQW absorption layer and the p-InP clad layer. In addition, a band discontinuity reduction layer having a band gap energy larger than that of the MQW absorption layer and smaller than that of an n-InP clad layer is provided between the MQW absorption layer and the n-InP clad layer. Consequently, as a pile-up of carriers is suppressed, a semiconductor light modulator with an enhanced response speed can be obtained.

Abstract: A resonance-type semiconductor optical modulator has an asymmetrical electrode structure in which the microwave power is applied to the semiconductor optical modulation element via a resonator. The resulting higher modulation voltage provides high modulation efficiency while controlling the amount of power consumption. The semiconductor optical modulation element includes an open-ended stub, a short-ended stub connected to the open-ended stub, a feeding line connected to both stubs and common electrodes. The stubs are formed in contact and the semiconductor optical modulation element is connected to the open-ended stub.

Abstract: An improved SLM that is capable of detecting when light incident on the SLM exceeds a predetermined threshold. A diode is fabricated around, or within the pixel array. Light incident on the array (and the diode) results in a current increase through the diode, which may detected and used to initiate a disable signal to control circuitry of the SLM.

Abstract: A multilevel light-intensity modulating circuit for suppressing the amplitude distortion regarding intermediate levels, caused by the conversion from a multilevel electric signal to a multilevel modulated optical signal. The circuit comprises a section for distributing an input optical carrier into n-channel optical carriers; n light-intensity modulators for modulating intensities of the optical carriers by using input two-level electric signals; a control section for producing a phase difference between the n-channel two-level modulated optical signals; a control section for assigning a different light intensity to each of the n-channel two-level modulated optical signals; and a section for combining the n-channel two-level modulated optical signals obtained via the control sections, and outputting a 2n-level modulated optical signal. The phase difference and the different light intensity are defined in advance so as to produce the 2n-level modulated optical signal.

Abstract: Light from a laser diode is directed by mirrors on angled surfaces of an optical unit through a first lens at an optical disc. Light returns from the disc on a parallel path through a second lens and is directed at a photodetector. A semiconductor device controls the operation of the laser diode and receives signals form the photodetector for processing. The optical unit is formed from one or two glass elements cut from a larger glass wafer or wafers using photolithographic techniques. The mirrors are formed by thin films deposited on angled glass surfaces formed by selective plasma etching of the wafers. At least one mirror is partially reflective and is formed by depositing a thin film of titanium nitride.

Abstract: An optical modulator which is suitable for use in high-speed optical communications and simultaneously satisfies demands for incident light of higher intensity and lower chirp. An absorption layer having a multi-quantum-well structure includes a well layer having a first bandgap energy, and a barrier layer having a second bandgap energy, the second bandgap energy being greater than the first bandgap energy and no less than 0.946 eV.

Abstract: Drive circuitry to provide a DC bias voltage and a high frequency modulation current to an electroabsorption modulator (EAM), including a high frequency modulation current source, a coupling capacitor, and a first DC lead. The drive circuitry may include termination circuitry. One lead of the high frequency modulation current source is electrically coupled to the first semiconductor type contact of the EAM and the other lead of the high frequency modulation current source is electrically coupled to an AC ground. The coupling capacitor includes a first electrode electrically coupled to the second semiconductor type contact of the EAM, a second electrode electrically coupled to the AC ground, and a dielectric layer between the electrodes. The first DC lead is electrically coupled to the EAM-side capacitor electrode and configured to be coupled to a first DC potential.

Abstract: According to the present invention, a feature of a waveguide type optical element and a method of manufacturing the same is to selectively diffuse Zn on a light absorption layer using an undope InP layer. Therefore, since impurity diffusion area is made on the light absorption layer under a ridge part, a depletion layer becomes thin in a thickness direction and an electric field can strongly be applied. Thereby, an extinction ratio characteristic of a device can be improved.

Abstract: An electro-optic modulator and associated method are provided. The electro-optic modulator includes an optical waveguide comprised of two pairs of coplanar modulation strips, the strips being driven by a controller circuit which applies voltages of equal amplitude and opposite polarity to the strips of each pair. The voltage applied to the first pair of strips may differ from the voltage applied to the second pair of strips, so that a chirp factor may be adjusted if desired. The modulator and associated method exhibit reduced drive voltage requirements.

Abstract: According to the voltage-current characteristic of a diode mounted on a high-frequency circuit substrate, a waveform of an applied electric signal is shaped into a desired waveform and applied to an electroabsorbing light modulating semiconductor element. The waveform of the modulated output light output from the optical modulator is highly improved although the extinction characteristic of the light modulating semiconductor element is not linear.

Abstract: Electro-optic elements are formed in metal oxide films, such as lithium niobate, on a substrate such as lithium niobate for utilization in electro-optical devices. The electro-optic elements include trenches in the lithium niobate selected to improve the performance of the device. Traveling wave modulators may be formed with a waveguide having first and second arms, electrodes over the lithium niobate layer, and trenches formed in the layer to focus the electric field in the waveguide, resulting in improved modulator performance.

Abstract: A system for performing real time optical comparisons using an optical correlator permits comparing a sampled image to a wide variety of reference images through the utilization of a multiple quantum well spatial light modulator which is utilized to rapidly present a large number of reference images for correlation. The utilization of the multiple quantum well spatial light modulator as the spatial light modulator in a van der Lugt image correlator in combination with a spectrometer permits optical comparisons at 300,000 frames per second versus 10,000 frames per second, the best case for liquid crystal based spatial light modulators.

Abstract: A device is provided for generating a photonic signal having a phase different from an input photonic signal that is incident on the device. The input photonic signal has an signal frequency, signal bandwidth, and a signal intensity. The device comprises a plurality of material layers. The material layers are arranged such that the device exhibits a photonic band gap structure. The photonic band gap structure exhibits a transmission band edge that corresponds to the input photonic signal frequency. A second photonic signal is generated at a second photonic frequency preferably close to a second band edge. The interaction of the input photonic signal with the second photonic signal generates a phase shift of order &pgr; for relatively small input intensities.

Abstract: An electrophoretic display device includes a first display electrode and a second display electrode placed on a first substrate, and a second substrate placed in opposition to the first substrate through a bulkhead. Auxiliary display electrodes (projections), each of a projecting structure, are provided on the first display electrode and the second display electrode and along lines of portions where an absolute value of a horizontal component of an electric field generated over the first display electrode and the second display electrode, becomes minimum. A space formed by the first substrate, the second substrate, and the bulkhead is filled with a transparent insulating liquid, and colored electrophoretic particles are dispersed in the insulating liquid.

Abstract: An exemplary monolithic stabilized monolithic transmissive active optical device, such as an electroabsorption modulator (EAM), a variable optical attenuator (VOA), or a semiconductor optical amplifier (SOA), with an output optical tap, includes: a substrate; a waveguide layer; a semiconductor layer. The waveguide layer is coupled to the substrate and includes an active medium, which interacts with a predetermined wavelength of light, and is responsive to an electric signal. The electric signal is applied between the substrate and the semiconductor layer. The waveguide layer includes an output optical tap section and an active section adjacent to the output optical tap section. These sections include portions of the active medium. Further embodiments of the present invention incorporate temperature as well as bias control to improve performance of exemplary monolithic transmissive active optical devices. Additional embodiments include exemplary methods of manufacture and methods of operation.

Abstract: Micro fabricated arrays of optical modulators of both a surface electrode and machined mesa nature where the small structure size and low capacitance electrical connections permit each modulator element to be individually electrically addressed thus providing modulator optical rise and fall response times in the low and sub nanosecond range. Both sparsely spaced and closely packed arrays are achieved.

Abstract: An apparatus and method for filtering an optical input is disclosed. In an illustrative embodiment, an optical input is split into polarization components along separate paths. The polarization components are then fed into a first electro-optic device that includes a set of electrodes across which a voltage is applied to adjust a wavelength transmission characteristic of the device. A section of the first device positioned between the electrodes preferably has a birefringence that is adjusted depending on the voltage applied across the electrodes. The adjusted components of the optical input are thereafter combined to produce an optical output. Accordingly, the optical input can be attenuated based on the voltage applied to electrodes of the first electro-optic device.

Abstract: A method and apparatus for modulating an optical signal using a micromechanical modulator are disclosed. The modulator comprises a membrane, which includes a first and a second layer, a substrate layer, and a substrate, spaced from the membrane to form an air gap. The layers of the membrane are characterized in that there is a relationship between the refractive indices of the layers and the refractive index of the substrate. The membrane is suspended in a first position over the substrate by a flexible support arrangement. Bias is applied to the membrane and the substrate to create an electrostatic force to move the membrane towards the substrate to a second position. The reflectivity of the device to an optical signal changes as the membrane moves from the first position to the second position, thereby modulating the signal.

Abstract: A conductive substrate supports an array of multi-channel optical attenuating devices. Each attenuating device includes a membrane with an optically transparent portion And a flexible support for positioning the optically transparent portion of the membrane spaced from the substrate for defining an air gap. The air gap constitutes a cross-shaped gap-chamber having a horizontally and vertically elongated chambers extended from a central intersection area functioning as an optical active area. A voltage bias circuit applies an electrical bias between the conductive substrate and the membrane to adjust and control an air-gap thickness at the optical active area between the conductive substrate and the membrane. Each of the devices can be manufactured on the same silicon wafer using the same process and can be individually controlled to accommodate different wavelength attenuation at each channel. Production costs, and time and efforts required for aligning the array to optical fibers are also reduced.

Abstract: An optical modulator that modulates light through the back side of a flip chip packaged integrated circuit die. In one embodiment, an optical modulator includes a p-n junction having a side wall that is substantially vertical or perpendicular relative to a surface of the integrated circuit die. A charged region is generated at the p-n junction and is modulated in response to an electrical signal of the integrated circuit die. An optical beam is directed through the back side, of the semiconductor substrate and through the charged region along the side wall p-n junction. The optical beam is deflected off a deflector back through the charged region along the side wall back out the back side. In one embodiment, the side wall p-n junction is provided with a metal oxide semiconductor (MOS) gate structure. In another embodiment, the side wall p-n junction is provided by an n− (or p−) well in a p− (or n−) epitaxy layer of the semiconductor substrate.

Abstract: An optical modulator and a semiconductor laser device including the optical modulator, both reducing variations in the refractive index of an optical modulator or making variations negative without an increase in loss or a decrease in extinction ratio, as well as an optical communications system increasing an interval of distance at which modulated light is transmitted, by use of the optical modulator and the semiconductor laser device including the optical modulator. The optical modulator includes a semiconductor substrate of a first conductivity type; a light absorption layer on the semiconductor substrate and having a multiple quantum well structure, the multiple quantum well structure including a first well layer and second well layers. The peak wavelength of the absorption spectrum of the second well layers is shorter than the peak wavelength of the absorption spectrum of the first well layers A semiconductor cladding layer of the second conductivity type is on the light absorption layer.

Abstract: A photonic band gap structure device and method for delaying photonic signals of a predetermined frequency and a predetermined bandwidth by a predetermined delay is provided. A Fabry-Perot delay line device has several regions of periodically alternating refractive material layers which exhibit a series of photonic band gaps and a periodicity defect region, interposed between the regions of periodically alternating refractive material layers. The Fabry-Perot delay line device imparts a predetermined delay to photonic signals that pass therethrough. The introduction of the periodicity defect region into this photonic band gap structure creates a sharp transmission resonance within the corresponding photonic band gap of the structure and causes at least an order of magnitude improvement in photonic signal delay for a band-edge delay line device of similar size. Variable photonic delays to multiple photonic signals are also generated by this Fabry-Perot delay line device.

Abstract: A forming method and a structure of a high efficiency electro-optics device are disclosed. In the present invention, the cell-fixing surface between the die carrier and the electro-optics cell is decreased to increase the light emitting and absorbing regions of the electro-optics device. Thus, the operating efficiency and the sensitivity of the electro-optics device is increased substantially. Especially, the present invention has the advantage of fully showing the efficacy of device using the transparent substrate. Furthermore, when the electro-optics cell is fixing on the cell-fixing surface by utilizing the eutectic or metal-melting bonding method, a result of self-alignment can be achieved. Thus, the accuracy of the packaging device is increased substantially, thereby reducing the loss caused by the failure of poor cell-fixing while in mass production and meanwhile increasing the accuracy of fixing cell. Therefore, the present technology is quite suitable for use in the packaging of high precision.

Abstract: A semiconductor device for modulating an optical power light beam with an optical signal light beam contains a detector diode for absorbing the signal beam and a quantum well modulator diode for absorbing the power beam. Both diodes are reverse biased, allowing for absorption of the power beam at photon energies below the band gap energy of the quantum well layer. Absorption of the signal beam creates carriers that screen the field in the detector diode, lowering the bias voltage. Because top and bottom layers of the entire structure are made to be highly conductive, overall voltage is fixed, leading to a simultaneous change of voltage in the modulator diode, altering absorption by electroabsorption mechanisms. In a first embodiment, the diodes are oriented such that decreased voltage in the detector diode leads to decreased voltage in the modulator diode; the device is used as an optically controlled optical switch.

Abstract: A light modulating switch (210) including a switching element (218) having a first portion (226) of electro-optic material to which first and second electrodes (213, 224) are associated. A second portion (228) is composed of material having an index of refraction matching that of the first portion (226) when no voltage is applied to electro-optically activate the first portion (226), but the index of refraction of the second portion (228) is less than the index of refraction of the first portion (226) when the first portion (226) is electro-optically activated by application of voltage to the electrodes (213, 224).

Abstract: This relates to an electro-modulating device (10) for modulating light from a light source, as part of an opto-electronic communication network. The electro-modulating device (10) has a modulating medium (16) for modulating light passing therethrough by varying an electric field applied across the modulating medium (16), an optical input-output surface (21), a light reflector (28), and electrodes (15, 17) for applying the varying electric field across the modulating medium (16). The input-output surface (21), the medium (16) and the reflector (28) are arranged so that light enters the medium (16) through the input-output surface (21), travels through the medium (16) towards the reflector (28), is reflected by the reflector (28) to travel back through the medium (16) towards the input-output surface (21), and exits the medium (16) through the input-output surface (21).

Abstract: A semiconductor device includes a quantum well lamination structure having at least one quantum well layer and at least two barrier layers alternately laminated, the quantum well layer forming a quantum well relative to electron and hole and the barrier layer forming a potential barrier relative to electron and hole. The height of the quantum well layer and the height of the potential barrier of a valence band at the interface between the quantum well layer and the barrier layer are set so that the number of quantum levels relative to hole on the valence band side of the quantum well layer is two or three in the state that the intensity of an electric field generated in the quantum well layer is zero. The semiconductor device is provided with a means for applying an electric field in the quantum well lamination structure in a thickness direction.

Abstract: The optical domain optical signal sampling device is for sampling an optical signal-under-test and comprises a semiconductor saturable absorber, an optical sampling pulse source, an optical signal input and a light detector. The optical sampling pulse source is arranged to illuminate the semiconductor saturable absorber with optical sampling pulses. The optical signal input is arranged to illuminate the semiconductor saturable absorber with the optical signal-under-test. The light detector is arranged to receive optical samples of the optical signal-under-test output by the semiconductor saturable absorber in response to the optical sampling pulses.

Abstract: A device for switching an optical beam in an optical switch. In one embodiment, the disclosed optical switch includes an optical switching device disposed in a well region in a semiconductor substrate layer. In one embodiment, the well region has a higher doping concentration than the semiconductor substrate layer in which the well region is disposed. The optical switching device is optically coupled to an optical input port and an optical output port of the integrated circuit die.

Abstract: The present invention relates to an optical short pulse generator using an EA modulator. In addition to continuous wave light for generating an optical short pulse train, pump light for generating a pile up is injected into this EA modulator. Generating a pile up increases the number of photo-carriers which accumulate in the light absorption layer without being swept out to the clad layer, and this increases the change in the light absorption quantity when a sinusoidal electric field is applied to the EA modulator. The EA modulator in accordance with the present invention has excellent extinction characteristics so that it can generate an optical short pulse train whose loss is small and pulse width is very small. According to one preferred embodiment of the present invention, the pump light is injected into the light absorption layer of the EA modulator, not from the end face where continuous wave light is injected, but from the end face where the optical short pulse train is emitted.

Abstract: The present invention relates to a modulated light source (10), in particular for use as part of an opto-electronic communication network. The modulated light source (10) has a laser (12) and an external electro-optic modulator (16) for modulating the intensity of light produced by the laser (12). A temperature sensor (30) senses the temperature of the laser (12) and the modulator (16). A control circuit connected to the temperature sensor (30) adjusts the bias on the modulator (16) so that the band edge of the modulator follows the changes in wavelength of the laser (12) as the laser (12) warms up during operation. This avoids the need for a cooling element to keep the temperature of the laser (12) constant.