Abstract: A reflective semiconductor optical amplifier light source is disclosed. The reflective semiconductor optical amplifier light source includes a transmissive type semiconductor optical amplifier for creating and amplifying spontaneous emission light, a reflector for reflecting amplified spontaneous emission light outputted from the semiconductor optical amplifier such that amplified spontaneous emission light is reflected back into the semiconductor optical amplifier, and a bandpass filter having a predetermined wavelength band width for limiting wavelength bands of the amplified spontaneous emission light capable of passing through the bandpass filter. In one aspect of the invention, the bandpass filter is interposed between the semiconductor optical amplifier and the reflector. In another aspect, a polarization filter is imposed to limit the reflected emission light to a predetermined polarization.

Abstract: An optical signal processing method is disclosed that enables improvements of a signal to noise ratio of an optical signal and reduction of size and power of an optical signal processing device. The optical signal processing method includes steps of dividing an input optical signal into a first polarization optical component and a second polarization optical component orthogonal to the first polarization optical component; supplying the first polarization optical component to a first gain device whose gain saturates at a first value; supplying the second polarization optical component to a second gain device whose gain saturates at a second value less than the first value; combining output light from the first gain device and output light from the second gain device; and outputting the combined optical signal through a polarization element.

Abstract: This disclosure is concerned with digital optical circuits, including an optical astable multivibrator. In one example, an optical astable multivibrator is provided that includes a lasing semiconductor optical amplifier (LSOA), such as a VLSOA for example. The LSOA is optically coupled to a time delay component and includes a pump input, amplifier input, amplifier output, and a ballast laser output. The time delay component includes an input that is optically coupled with the ballast laser output of the LSOA. The time delay component further includes an output that is optically coupled with the amplifier input of the LSOA. The output of the LSOA is a clock signal having a periodic square waveform whose frequency is determined by the time delay component.

Abstract: An intergrated optical device comprises a vertically lasing semiconductor optical amplifier (VLSOA) and an optical element integrated onto a common substrate. Example optical elements include waveguides, unguided transparent regions, and active optical devices (including additional VLSOAs). The integrated device may be fabricated using a number of different methods, including based on selective area epitaxy, impurity induced disordering, etch and fill and silicon optical bench.

Abstract: A gain-clamped semiconductor optical amplifier having photo detectors which are integrated on a single crystal substrate can detect optical intensities at input/output terminals of the optical amplifier. The semiconductor optical amplifier includes a first conductive semiconductor substrate, a semiconductor optical amplifier formed on the semiconductor substrate so as to have a horizontal-direction lasing structure, and a first and a second photo detector formed respectively at positions of the semiconductor substrate spaced horizontally from an input side and an output side of the semiconductor optical amplifier so as to measure intensities of an input signal and an output signal of the semiconductor optical amplifier.

Abstract: An amplified laser comprising a semiconductor laser and semiconductor optical amplifier (SOA) mounted on a substrate such that an optical signal generated by the laser is optically coupled to the SOA. The SOA and laser are electrically coupled in a series configuration or a parallel configuration such that a single DC lead is needed to provide operational power and a single lead is needed to provide ground to both optical components. Additionally, a monolithic distributed feedback semiconductor laser (DFB) and SOA device comprising a substrate, a diffraction grating formed on the substrate, an active layer waveguide extending over the substrate and grating, a semiconductor layer formed over the active layer, and an electrical contact layer including varying resistive elements formed on the semiconductor layer. Either device may be contained in an industry standard 7-PIN electro-absorption modulated laser (EML) package.

Abstract: After forming domain inverted layers 3 in an LiTaO3 substrate 1, an optical waveguide is formed. By performing low-temperature annealing for the optical wavelength conversion element thus formed, a stable proton exchange layer 8 is formed, where an increase in refractive index generated during high-temperature annealing is lowered, thereby providing a stable optical wavelength conversion element. Thus, the phase-matched wavelength becomes constant, and variation in harmonic wave output is eliminated. Consequently, with respect to an optical wavelength conversion element utilizing a non-linear optical effect, a highly reliable element is provided.

Abstract: Systems and methods for tuning a DBR stack for an optical amplifier. The DBR layers in a mirror of the optical amplifier have a duty cycle that can be altered to tune a location of a channel drop in a gain spectrum. In addition to changing the duty cycle, the DBR stacks can be segmented. The segmented DBR stacks and/or the selected duty cycle tunes a location of a channel drop outside of a range of wavelengths of interest.

Abstract: An optical amplifier includes a first optical path, second optical path, semiconductor optical amplifier, and multi-mode interference 3-dB coupler. The first optical path guides oscillation light. The second optical path guides signal light. The semiconductor optical amplifier causes oscillation on the first optical path. The multi-mode interference 3-dB coupler crosses the first and optical paths in the gain medium of the semiconductor optical amplifier.

Abstract: A semiconductor optical amplifier for amplifying input optical signals is disclosed. The optical amplifier includes a substrate; a first active layer laminated on the substrate for generating pumping lights; a second active layer laminated on the substrate being gain-clamped by the pumping light and amplifying the input optical signals; and a grating formed on an upper portion of the substrate, adjacent to a boundary between the first active layer and the second active layer, for partially allowing the transmission of the pumping lights to the second active layer and partially reflecting the pumping lights.

Abstract: An optical amplifier is disclosed comprising a signal semiconductor optical amplifier having a waveguide, forming at least part of a signal path between an input and an output, extending along a signal active region for amplification of a signal. The amplifier also includes a control active region of semiconductor material having a gain which is controllable independently from the gain of the signal active region. The amplifier also includes a laser cavity containing both the signal active region and the control active region and being capable of clamping the gain of the signal active region, and the control active region is arranged not to amplify a signal in the signal path within a predetermined signal band.

Abstract: An optical amplifier having a uniform gain profile uses a photonic crystal to tune the density-of-states of a gain medium so as to modify the light emission rate between atomic states. The density-of-states of the gain medium is tuned by selecting the size, shape, dielectric constant, and spacing of a plurality of microcavity defects in the photonic crystal. The optical amplifier is particularly useful for the regeneration of DWDM signals in long optical fibers.

Abstract: An improved gain-clamped optical amplifier is disclosed. A series of laser cavities are placed along the amplifier axis. The laser cavities are designed such that the carrier densities of the amplifier decline toward the signal output end. Since the gain clamping amplitudes at positions along the amplifier can be different, we have the freedom to optimize the optical gain at all location, to minimize the noise impact at the signal input end, and to maximize the saturation output power at the signal output end. In addition, carrier levering effect realized by gain/loss wings further lowers the noise figure, and extends the optical gain and saturation output power. An ideal optical amplifier with high linear gain, small noise figure, and large saturation output power and extended dynamic range is then achieved. Energy saving is the bonus of using the invented amplifiers.

Abstract: A wavelength conversion device includes a photodetector for generating a photocurrent in response to the detection of radiation at a first wavelength. An avalanche multiplier amplifies the signal photocurrent and feeds this to a light emitting element that produces radiation at a second wavelength shorter than the first wavelength and corresponding to the detected radiation at the first wavelength. The components are assembled together in an integrated stacked arrangement either by epitaxial growth or wafer fusion of the individual components. The device is useful as an image intensifier or thermal imaging device.

Abstract: An optical bandwidth source for generating amplified spontaneous emission (ASE) across a selected wavelength range, the optical bandwidth source including a waveguide having a first end and a second end, and comprising a plurality of separate wavelength gain subsections arranged in a serial configuration between the first end and the second end so as to collectively form an active waveguide between the first end and the second end; wherein each of the wavelength gain subsections is configured to produce ASE across a wavelength range which is less than, but contained within, the selected wavelength range, whereby the plurality of separate wavelength gain subsections collectively produce ASE across the selected wavelength range.

Abstract: An improved optical transmitter comprises a vertically lasing semiconductor optical amplifier (VLSOA) coupled to an external modulator and/or a laser source. The VLSOA, external modulator and laser source are discrete devices or alternatively integrated onto a common substrate. The integrated optical transmitter may be fabricated using a number of different methods, including based on selective area epitaxy, impurity induced disordering, etch and fill and silicon optical bench.

Abstract: An optical function device capable of controlling an optical signal with another optical signal, wherein a modulated input light Iin of a wavelength ?1 is coupled with a bias light Ibias of a wavelength ?2, and the thus coupled input and bias lights are input to a first semiconductor optical amplifying element 48, so that the bias light Ibias is intensity-modulated in a phase reversed with respect to the input light Iin, while the input light Iin is cut by a first wavelength extracting element 56. A control light Ic of the wavelength ?1 is coupled with the intensity-modulated bias light Ibias of the wavelength ?2, and the thus coupled control and bias lights are input to a second optical amplifying element 50, so that the once reversed bias light Ibias of the wavelength ?2 is intensity-modulated with respect to the control light Ic of the wavelength ?1, and is extracted as an output light by a second wave extracting element 50.

Abstract: CMOS optical receiver and optical transmitters are described. The optical receiver is formed from a CMOS CCD which is modified to immediately output all information indicative of incoming light, i.e., with no transfer gate. The optical transmitter is formed of a modulation window device. Both the optical transmitter and optical receiver are located on-chip with a microprocessor and form the I/O for the microprocessor. Since the modified I/O is serial, a serial to parallel converter, and parallel to serial converter are provided.

Abstract: Systems and methods for extending a linear range of a semiconductor optical amplifier (SOA). A feedback layer is included in an SOA. The optical mode of the SOA is distributed between the feedback layer and the active region. As output optical power increases, the mode confinement of the active region increases and the mode is drawn from the feedback layer into the active region. The increase in the mode confinement offsets a loss of material gain such that the linear range of the SOA is extended. In one embodiment, the modal gain increases an higher output optical powers.

Abstract: High power, low degree of polarization superluminescent diodes (SLDS) are described. A semiconductor optical amplifier (SOA) which amplifies light in substantially one polarizaton state can be used to create a SLD by combining the output from both sides of this polarization sensitive SOA in a manner which results in a depolarized output.

Abstract: A reflective semiconductor optical amplifier includes a substrate, a waveguide with a buried heterostructure formed by sequentially laminating a lower cladding, an active layer, and an upper cladding on the substrate, the waveguide including, sequentially, respective straight line, curved and tapered waveguide regions. A current blocking layer surrounds the waveguide to prevent electric current from flowing outside the active layer. Selectively etching portions of the current blocking layer and the substrate around the waveguide forms a trench to reduce parasitic capacitance. Further features include a window region on one end of the tapered waveguide region, an anti-reflection surface on one end of the window region, and a high-reflection surface on one end of the straight line waveguide region.

Abstract: An optical crossbar switch is described that minimizes the number of electrical components and optimizes the conversion between optical and electrical signals. Utilizing various characteristics of lasing semiconductor optical amplifiers, the optical crossbar switch provides optical components in place of traditionally used electrical components. For example, an optical buffer is described that delays an optical signal a sufficient amount of time for a path to be created for the optical signal through the optical crossbar. Additionally, a monitor/detector circuit utilizes a ballast laser signal emitted from a lasing SOA during amplification of an optical signal in order to convert optical routing information to an electrical equivalent. As a result of the multiple uses of lasing semiconductor optical amplifiers, the bandwidth of the described optical crossbar switch is greater than traditional optical crossbar switches currently in use.

Abstract: A multi-section filter is provided for use in processing optical signals and other signals that can be readily projected from one filter section to another. Filters of the invention can be configured in numerous forms, including IIR and FIR filters and both linear and 2D active optical lattice filters. Filter sections are coupled together by means of four direction couplers and surface grating couplers, and may be implemented as GSE photonic integrated circuit devices.

Abstract: A clock recovery system and related method are disclosed. One example of the clock recovery system includes an optical detector and lasing SOA that are arranged so that the optical detector detects ballast laser light emitted by the lasing SOA. The optical detector includes an output that is connected to a first input of a phase detector that includes both first and second inputs. A filter is included in the clock recovery system as well and has an input and an output, the input being connected to the output of the phase detector. Finally, this example of the clock recovery system includes an oscillator having an input and an output arranged so that the input of the oscillator is connected to the output of the filter, and the output of the oscillator is connected with the second input of the phase detector.

Abstract: A gain-clamped semiconductor optical amplifier uses the Raman amplification principle. A Raman amplifier and a gain clamped semiconductor optical amplifier are integrated onto an optical amplifier module. The gain-clamped semiconductor optical amplifier includes: an optical fiber having Raman gain characteristics; and a gain-clamped semiconductor optical amplifier for providing a pumping light to the optical fiber by laser oscillation using a distributed Bragg reflector (DBR) lattice. The DBR has input and output terminals asymmetrical to each other, at least for amplifying a signal light Raman-amplified by the optical fiber.

Abstract: An optical amplification device includes a depolarizer for reducing the polarization sensitivity requirements on an SOA by changing the input to the SOA from having an arbitrary (unknown) polarization state to a known (depolarized) state. The depolarizer receives an input optical signal and outputs a depolarized, optical signal, and a semiconductor optical amplifier (SOA) receives the depolarized optical signal and outputs an amplified optical signal.

Abstract: An active optical device with reduced axial carrier depletion is disclosed. This active optical device includes a substrate layer; a p-doped active layer coupled to the substrate, a semiconductor layer coupled to the active layer, an electrical contact coupled to the substrate layer, and an electrical contact coupled to the semiconductor layer. The p-doped active layer has a central interaction region and a transverse diffusion region. The transverse diffusion region supplies additional carriers to the central interaction region in response to carrier depletion in the central interaction region caused by the interaction of the carriers with a light beam. Also a method of operation and a method of manufacture for the active optical device is disclosed.

Abstract: An all-optical linear feedback circuit for use, for example, as a maximal length pseudo random bit sequence generator includes an all-optical logic circuit that is capable of generating 2N?1 bit maximal length pseudo random bit sequences on an optical channel at high data rates e.g. 80 Gbit/s. In the pseudo random bit sequence generator of the present invention, intensity-dependent phase modulation of at least one included semiconductor optical amplifier (SOA) is implemented. The maximum data rate is limited by the fast gain recovery time of the carriers in the SOA. An optical logic gate of the pseudo random bit sequence generator of the present invention may be constructed using various nonlinear elements that provide ultra-fast intensity-dependent phase modulation.

Abstract: A VLSOA is used as a wavelength converter. The signal is input to the VLSOA, and the laser output carries the signal on a second wavelength.

Abstract: A switching element capable of being used in an optical processing device includes an optical signal separator operable to separate a multiple wavelength optical signal into one or more optical signal wavelengths. The switching element further includes a plurality of semiconductor optical amplifiers located on a single semiconductor substrate. The plurality of semiconductor optical amplifiers operable to perform an optical switching operation on at least one of the optical signal wavelengths. The switching element also includes a controller operable to generate a control signal that affects the optical switching operation performed by one or more of the plurality of semiconductor optical amplifiers.

Abstract: An optical amplifier with damped relaxation oscillation. A large distance between mirrors in a VLSOA increases damping for the relaxation oscillation. Alternatively, a feedback loop damps out relaxation oscillations.

Abstract: A transverse Bragg resonance waveguide is comprised of a waveguiding channel, and on at least two opposing sides of the channel two periodic index media; and a means for providing gain in the periodic index media. In one embodiment the waveguiding channel is planar and is sandwiched on two opposing sides by the periodic index media. In another embodiment the waveguiding channel is cylindrical and is surrounded by the periodic index media. The means for providing gain in the periodic index media is electrical or optical pumping. The periodic index media comprises a periodic lattice of regions having an index of refraction distinct from the channel, such as an array of transverse holes defined in a planar semiconductor substrate in which the channel is also defined, or an array of longitudinal holes defined in a cylindrical semiconductor fiber in which the channel is also longitudinally defined.

Abstract: The present invention relates to a method of embodying all-optical XOR logic gate by using semiconductor optical amplifier, and more particularly, to a technique to embody all-optical XOR logic gate utilizing the cross-gain modulation (XGM) characteristic of semiconductor optical amplifiers controllable with input currents, illumination signal, and pumping signal. The method of all-optical XOR logic element in accordance with the present invention is characterized to obtain operational characteristic of the all-optical XOR logic element by inputting pump-signal and illumination signal concurrently into two semiconductor optical amplifiers and then summing the two output signals having XGM characteristic arising from gain saturation and wavelength conversion of the semiconductor optical amplifiers.

Abstract: A method and apparatus for providing optical 3R regeneration involving: 1) generating an encoded optical clock signal from at least an optical signal; 2) introducing the encoded clock signal into a delay interference section of a regenerator such that an amplitude modulated clock signal is produced; andoutputting the amplitude modulated clock signal wherein the output amplitude modulated clock signal preserves information present within the input optical signal.

Abstract: An improved optical receiver comprises a vertically lasing semiconductor optical amplifier (VLSOA) coupled to a photodetector. The VLSOA and photodetector are discrete devices or alternatively integrated onto a common substrate. The integrated optical receiver may be fabricated using a number of different methods, including based on selective area epitaxy, impurity induced disordering, etch and fill and silicon optical bench.

Abstract: Optical systems and devices are provided that include or facilitate the ability to provide early detection of the failure of an optical transmitter such as a laser. Such detection may be made with reference to various aspects of the operation and performance of the optical transmitter. For example, some of the optical systems and devices employ wavelength shift information to make determinations concerning potential failure of an optical transmitter. Other optical systems and devices use information concerning the efficiency with which an incoming pump current is converted into the ballast laser signal changes to make determinations concerning potential failure of an optical transmitter.

Abstract: The invention relates to a semiconductor optical amplifier including a buried guide active structure (12), characterized in that the guide active structure (12) is subjected to an external stress to render the gain of said amplifier insensitive to the polarization of the light to be amplified, said external stress coming from a force induced by a deposit of a material (50) against a ridge (15) surrounding said guide active structure (12).

Abstract: An active optical device with reduced axial carrier depletion is disclosed. This active optical device includes a substrate layer; a p-doped active layer coupled to the substrate, a semiconductor layer coupled to the active layer, an electrical contact coupled to the substrate layer, and an electrical contact coupled to the semiconductor layer. The p-doped active layer has a central interaction region and a transverse diffusion region. The transverse diffusion region supplies additional carriers to the central interaction region in response to carrier depletion in the central interaction region caused by the interaction of the carriers with a light beam. Also a method of operation and a method of manufacture for the active optical device is disclosed.

Abstract: A multi-stage tunable gain optical amplifier device amplifies an optical signal by a gain amount which can be adjusted in one of the stages of the amplifier. The multi-stage amplifier includes at least two optical amplifier stages coupled in series, one of which is a tunable gain amplifier stage. The optical amplifier stages are characterized by a design parameter which varies from stage to stage. In a preferred embodiment, the design parameter includes a noise figure and a saturable power, with both parameters increasing as the optical signal propagates from stage to stage. As a result, the multi-stage tunable gain optical amplifier can achieve better noise performance and higher output power than a single stage optical amplifier with a constant noise figure and saturable power.

Abstract: An optical amplifier has two amplifying sections formed in a semiconductor structure. The two amplifying sections have different ratios of gain for two polarization states (e.g., TE and TM). Thus the amplifier as a whole has a gain ratio determined by the gains of the two amplifying sections. The two amplifying sections are separately electronically controllable so as to control the gains of the two amplifying sections and thus the gain ratio of the amplifier as a whole. Such an amplifier can be made by quantum well intermixing.

Abstract: An optical amplifier has a spatially varying absorption spectrum formed in a monolithic InGaAsP structure whose quantum well active structure has modified effective bandgap properties. The effective bandgap properties can be modified by rapid thermal annealing to cause the diffusion of defects from one or two InP defect layers into the quantum well active structure. Multiple such optical amplifiers, having their effective bandgap properties modified to provide different gain spectra, can be monolithically formed in a single semiconductor structure for broadband amplification, in which case their individual gain spectra can be controlled to control the total gain spectrum dynamically. Alternatively, the optical amplifier can be used in a Mach-Zehnder wavelength converter for broadband wavelength conversion.

Abstract: A resonant-cavity light-emitting diode includes a semiconductor light-emitting layer sandwiched between an under and an upper semiconductor distributed Bragg reflector mirror layer, which are formed on the substrate, a light extracting section formed on the upper semiconductor distributed Bragg reflector mirror layer and having an opening to extract light from the semiconductor light-emitting layer, and a groove formed by removing portions of the semiconductor light-emitting layer, under and upper semiconductor distributed Bragg reflector mirror layers which lie in a peripheral portion of the opening of the light extraction section and reach the under semiconductor distributed Bragg reflector mirror layer, the inner wall of the groove being formed to reflect part of light emitted from the semiconductor light-emitting layer into the groove.

Abstract: Optical amplifier according to the present invention is provided with an EDF, a light source device having a semiconductor laser element that generates an excitation beam and a housing that accommodates this, and an optical multiplexer having an input optically coupled with light source device, an input that receives the signal beam, and an output that provides an excitation beam and signal beam to EDF. Semiconductor laser element has an active layer, provided between cladding layers and including compound semiconductors of mutually different conductivity types, that includes a compound semiconductor and is constructed such that the oscillation wavelength at 20° C. of this semiconductor laser element is less than 1470 nm but not less 1440 nm. If this is done, the change of gain in EDF with respect to oscillation wavelength can be made satisfactorily small and the NF can be made satisfactorily small.

Abstract: The invention relates to an optical amplifier device including a semiconductor optical amplifier component (1) including a guide active structure (12), characterized in that the guide active structure (12) is subjected to a stress external to said component (1) coming from integrating said component (1) in said device, and in that said component (1) has a controlled sensitivity to the state of polarization of the light to be amplified in order to render the gain of said optical amplifier device insensitive to the polarization of said light to be amplified.

Abstract: A gain-clamped semiconductor optical amplifier capable of providing constant gain for output optical signals at substantially all times is disclosed. In particular, the gain-clamped semiconductor optical amplifier according to the present invention comprises a active waveguide having an input and output side; clad layers surrounding the active waveguide; and a grating, which is formed partially at both end parts under the input and output sides of the active waveguide.

Abstract: An optical radiation amplifier, including an input port which receives the optical radiation and a first semiconductor optical amplifier (SOA), which is coupled to receive the optical radiation from the input port and is adapted to amplify the optical radiation to produce amplified optical radiation in response to a first current injected into the first SOA. The amplifier also includes an electro-absorption modulator (EAM), which is coupled to receive the amplified optical radiation and is adapted to modulate the amplified optical radiation in response to a modulation voltage applied to the EAM so as to produce modulated radiation. There is a second SOA, which is coupled to receive the modulated radiation and is adapted to amplify the modulated radiation in response to a second current injected into the second SOA.

Abstract: There is provided a non-linear optical device for enhancing the bandwidth accessible in the nonlinear generation of an optical signal. The device comprises a planar optical waveguide, the planar optical waveguide being operative to generate an optical output from an optical input having an input bandwidth by means of a non-linear optical process, the optical output having a wavelength within an accessible bandwidth, wherein the planar optical waveguide is operative to enhance the accessible bandwidth such that the ratio of the accessible bandwidth to the input bandwidth is at least 4. The device is particularly applicable to broad optical continuum generation, but may also be used in a parametric oscillator or amplifier arrangement with broad tuning range.

Abstract: An active optical device with reduced axial carrier depletion is disclosed. This active optical device includes a substrate layer; a p-doped active layer coupled to the substrate, a semiconductor layer coupled to the active layer, an electrical contact coupled to the substrate layer, and an electrical contact coupled to the semiconductor layer. The p-doped active layer has a central interaction region and a transverse diffusion region. The transverse diffusion region supplies additional carriers to the central interaction region in response to carrier depletion in the central interaction region caused by the interaction of the carriers with a light beam. Also a method of operation and a method of manufacture for the active optical device is disclosed.

Abstract: Techniques for amplifying light produced by a quantum cascade laser are described. An assembly according to the present invention includes an optical amplifier having an optical input and an optical output. The optical output has an area significantly greater than that of the optical output and the geometry of the amplifier is such that the amplifier widens from the optical input to the optical output. The optical amplifier is formed of a layered waveguide structure which achieves quantum confinement of electrons and photons within the active region. A distributed feedback laser is suitably coupled to the optical amplifier at the optical input of the amplifier. The widening of the amplifier makes available a large number of electrons, so that the amplifier is able to produce many photons resulting from stimulated transitions caused by introduction of light to the optical input of the amplifier, even if the great majority of the transitions occur nonradiatively.

Abstract: A semiconductor optical amplifier (SOA) apparatus and related methods are described. The SOA comprises a signal waveguide for guiding an optical signal along a signal path, and further comprises one or more laser cavities having a gain medium lying outside the signal waveguide, the gain medium being sufficiently close to the signal waveguide such that, when the gain medium is pumped with an excitation current, the optical signal traveling down the signal waveguide is amplified by an evanescent coupling effect with the laser cavity. When the gain medium is sufficiently pumped to cause lasing action in the laser cavity, gain-clamped amplification of the optical signal is achieved.