Abstract: This surface emitting semiconductor device 1 comprises a first conductivity type semiconductor region, an active layer, a second conductivity type semiconductor layer and current block semiconductor region. The first conductivity type semiconductor region is provided on a surface made of GaAs semiconductor. The active layer is provided on the first conductivity type semiconductor region. The active layer has a side surface. The second conductivity type semiconductor layer is provided on the active layer. The second conductivity type semiconductor layer has a side surface. The current block semiconductor region is provided on the side surface of the active layer and on the side surface of the second conductivity type semiconductor layer. The active layer is made of III-V compound semiconductor including at least nitrogen element as a V group element.

Abstract: Provided are a reflective semiconductor optical amplifier (R-SOA) and a superluminescent diode (SLD). The R-SOA includes: a substrate; an optical waveguide including a lower clad layer, an active layer independent of the polarization of light, and an upper clad layer sequentially stacked on the substrate, the optical waveguide comprising linear, curved, and tapered waveguide areas; and a current blocking layer formed around the optical waveguide to block a flow of current out of the active layer, wherein the linear and curved waveguide areas have a single buried hetero (BH) structure, and the tapered waveguide area has a dual BH structure.

Abstract: The wavelength converter comprises (1) an optical multiplexer for multiplexing an amplitude-modulated first light and reference light, which is continuous light having a wavelength different from the wavelength of the first light, (2) an optical fiber for propagating the multiplexed light therethrough to generate a third light by a non-linear optical phenomenon, and (3) an optical filter having a pass wavelength range set such that a pulse time width of the third light is 20% or more narrower than a pulse time width of the first light after the third light has passed through the optical filter, or (3?) an optical filter having a pass wavelength range set such that a cross point of an eye pattern of the third light is lower than a cross point of an eye pattern of the first light after the third light has passed through the optical filter.

Abstract: On the upstream side of a quantum dot optical amplifier, a polarization beam splitter with one input and two outputs is provided. Two optical fibers connected to output sections of the polarization beam splitter are connected to input sections of the quantum dot optical amplifier in a state that both of the optical fibers have an electric field whose direction being adjusted to maximize its gain, and one optical fiber is twisted by 90° to the other optical fiber. On the downstream side of the quantum dot optical amplifier, a polarization beam splitter with two inputs and one output is provided. Between two optical fibers connected to the polarization beam splitter, one is twisted by 90° to the other. This twisting direction is reverse to the twisting direction of the two optical fibers connected to the input sections of the quantum dot optical amplifier.

Abstract: The field of the invention is that of devices for regenerating optical signals. It applies more particularly to systems for high-throughput long distance transmission by optical fibres of digital data. While propagating, optical signals necessarily experience attenuation and degradation of their signal/noise ratio. To compensate for these degradations, wholly-optical regeneration devices are generally used. The object of the invention is to ensure regeneration which in large part eliminates noise, without using auxiliary optical devices. This regeneration is ensured by a structure with saturable optical absorbent comprising an optical cavity of thickness L comprising at least one layer of active material of Henry factor ?H and of maximum absorption variation ?? such that the thickness L equals about 2?/(?H, ??).

Abstract: A regenerator for restoring the originally encoded optical phase of a differential-phase-shift-keyed signal. In an embodiment, the regenerator simultaneously provides limiting amplification and reduces amplitude noise based on a phase-sensitive optical amplifier that combines a weak signal field of a degraded input data with a strong pump field supplied by a local oscillator in a nonlinear interferometer. The two fields interact through degenerate four-wave mixing, and optical energy is transferred from the pump to the signal and vice versa. The phase sensitive nature of the optical gain leads to amplification of a specific phase component of the signal, determined by the input pump-signal phase difference and the incident signal phase is restored to two distinct states, separated by 180° according to the original encoding. Simultaneously, gain saturation of the pump wave by the signal wave results in limiting amplification of the signal wave for removing signal amplitude noise.

Abstract: The field of the invention is that of devices for regenerating optical signals. It applies more particularly to systems for high-throughput long distance transmission by optical fibers of digital data. While propagating, optical signals necessarily experience attenuation and degradation of their signal/noise ratio. To compensate for these degradations, wholly-optical regeneration devices are generally used. The object of the invention is to ensure regeneration which in large part eliminates noise, without using auxiliary optical devices. This regeneration is ensured by a structure with saturable optical absorbent comprising an optical cavity of thickness L comprising at least one layer of active material of Henry factor ?H and of maximum absorption variation ?? such that the thickness L equals about 2?/(?H ??).

Abstract: An optical wavelength converter includes: a first branch passage and a second branch passage receiving direct current light, one of the first branch passage and the second branch passage receiving input signal light; wavelength converting semiconductor optical amplifiers inserted into the first branch passage and the second branch passage, respectively; and a signal amplifying semiconductor optical amplifier for amplifying the input signal light, which is coupled with a port through which the input signal light is input to one of the first branch passage and the second branch passage. In the optical wavelength converter, differential gain of the signal amplifying semiconductor optical amplifier at a wavelength of the input signal light is less than differential gain of the wavelength converting semiconductor optical amplifier at the wavelength of the direct current light.

Abstract: The invention provides a device and a method for extending the bandwidth of short wavelength and long wavelength fiber optic lengths. The invention provides for an optical transmitter package device comprising: a laser diode; and a semiconductor optical amplifier connected directly after and in close proximity to the laser diode, wherein the semiconductor optical amplifier is adapted to operate in a frequency domain such that the semiconductor optical amplifier filters and reshapes optical wavelengths from the laser diode, and wherein the semiconductor optical amplifier is biased below an amplification threshold for the semiconductor optical amplifier. The device may also comprises a feedback circuit which comprises an optical splitter, wherein the feedback circuit samples reshaped optical output from the semiconductor optical amplifier and dynamically adjusts one or both of the semiconductor optical amplifier and the laser diode.

Abstract: An optical amplifier including: an amplifier having an input port and an output port, which is disposed along a main signal line of the optical amplifier; a dummy laser generation circuit having an output coupled to the main signal line and operative for inputting a dummy signal into the amplifier; a first optical detector for detecting a power level of the dummy signal into the amplifier and outputting a first power level signal; a second optical detector for detecting an amplified power level of the dummy signal output by the amplifier and outputting a second power level signal; a memory device for storing calibration data regarding the gain characteristics of the amplifier; and a gain control circuit which receives inputs from the first optical detector and second optical detector, and has an output coupled to the amplifier. The gain control circuit operates to control the gain of the amplifier based on the first power level signal, the second power level signal and the calibration data.

Abstract: A semiconductor optical amplifier (SOA) with efficient current injection is described. Injection current density is controlled to be higher in some areas and lower in others to provide, e.g., improved saturation power and/or noise figure. Controlled injection current can be accomplished by varying the resistivity of the current injection electrode. This, in turn, can be accomplished by patterning openings in the dielectric layer above the current injection metallization in a manner which varies the series resistance along the length of the device.

Abstract: A gain-clamped semiconductor optical amplifier is disclosed. The amplifier includes a gain waveguide for amplifying an optical signal input to the gain waveguide, and a grating layer, in contact with the gain waveguide, having a first grating disposed at a first end portion.

Abstract: The present disclosure relates to the use of III-nitride wide bandgap semiconductor materials for optical communications. In one embodiment, an optical device includes an optical waveguide device fabricated using a III-nitride semiconductor material. The III-nitride semiconductor material provides for an electrically controllable refractive index. The optical waveguide device provides for high speed optical communications in an infrared wavelength region. In one embodiment, an optical amplifier is provided using optical coatings at the facet ends of a waveguide formed of erbium-doped III-nitride semiconductor materials.

Abstract: Wavelength converter and methods are based on cross-gain modulation. The wavelength converter has two semiconductor optical amplifiers to perform double cross-gain modulations and double inversions. The first semiconductor optical amplifier performs a first cross-gain modulation on a first continuous wave light using the input light as a modulating light to generate an inverted first-stage cross-gain modulated light. The second semiconductor optical amplifier performs a second cross-gain modulation on a second continuous wave light using the first-stage cross-gain modulated light as a modulating light to generate a double-inverted output light. The output light is non-inverted with respect to the input light.

Abstract: A vertical cavity semiconductor optical photoamplifer (VCSOA) is used as a modulating retro-reflector (MRR) as a pixel in an array. The boundary of the cavity in the VCSOA forms a mirror for reflecting an incident light as an amplified output.

Abstract: An apparatus, including an optical ring resonator having a waveguide ring with substantially straight waveguide segments and bent waveguide segments. The bent waveguide segments are optically coupled to the substantially straight waveguide segments and have optical cores with substantially smaller cross-sectional areas than the substantially straight waveguide segments. The bent waveguide segments change a propagation direction of received light by more than ½ of a right angle.

Abstract: An optical pulse position modulation receiver relying on the gain dynamics in a semiconductor optical amplifier (SOA). Optical PPM signal pulses and periodic optical clock pulses at a different frequency and/or polarization than the signal pulses are coupled into an SOA. Due to the high optical power of the clock pulses, the SOA gain will drop to a small value after each clock pulse. The SOA will then amplify each signal pulse that follows the clock pulse, and the gain will depend on the delay between the signal pulse and the preceding optical clock pulse. The optical output of the SOA can then be converted to an electrical signal by a photodetector.

Abstract: Monitoring of the input power is performed on-chip and is used to monitor and maintain performance, detect failure and trigger network protection strategies. An optical power-monitoring technique uses a photodetector monolithically integrated with the semiconductor optical amplifier—Mach-Zehnder interferometer circuit to monitor the P2R device and keep the output stable while the input power varies.

Abstract: A semiconductor tunable laser (10) and an interferometer (12) coupled to the tunable laser (10) are monolithically fabricated in a semiconductor heterostructure. The laser also comprises a buried ridge stripe waveguide laser. The interferometer (12) has a semiconductor optical amplifier (38) coupled in each arm. A cross-gain semiconductor optical amplifier converter is coupled to the interferometer (12). The semiconductor optical amplifier (38) coupled in each arm is biased so that an optical path length difference between the two arms is in antiphase which results in destructive interference. The output of the tunable laser (10) is coupled to a coupler. A semiconductor optical amplifier (38) is used as a gain controller for the semiconductor optical amplifiers in the interferometer (12) to allow wavelength conversion over a larger range of input signal powers.

Abstract: An optical amplifier is disclosed having a relatively high gain and low noise figure across the broadband wavelength range. In an exemplary embodiment, the optical amplifier comprises an optical fiber including a core doped with a fluorescent material, the optical amplifier having an associated first noise figure. The optical amplifier also comprises a semiconductor optical amplifier portion being optically coupled to the optical fiber, the semiconductor optical amplifier portion having an associated second noise figure, wherein the first noise figure is less than the second noise figure.

Abstract: An optical integrated device includes a plurality of input optical waveguides connected respectively to a plurality of input ports provided on one end face of the optical integrated device, a single output optical waveguide connected to an output port, an optical coupler for optically coupling signal lights propagated along the plural input optical waveguides to the single output optical waveguide, and a semiconductor optical amplifier gate array formed from a plurality of semiconductor optical amplifiers provided on the input optical waveguides, respectively, and each having an electrode on the surface thereof. The optical integrated device further includes a plurality of signal lines formed on the surface of the optical integrated device in such a manner as to extend from the electrodes to an end face of the optical integrated device on which none of the input ports and the output port is provided.

Abstract: A semiconductor device, comprising a semiconductor stacking body configured so as to sandwich an active layer by a p-type semiconductor layer and an n-type semiconductor layer and having plural regions along the active layer, plural electrodes provided on the p-type semiconductor layer or the n-type semiconductor layer and provided one for each of the plural regions, and a switch operatively connected to at least one of the plural electrodes for switching bias voltage application directions, is configured such that each of the plural regions is forward biased by a voltage applied via the electrode and becomes an amplification region when the switch is turned to one side, and is backward biased by a voltage applied via the electrode and becomes an attenuation region when the switch is turned to the other side.

Abstract: Provided is an apparatus and method for simultaneous optical wavelength conversion and optical clock signal extraction using semiconductor optical amplifiers (SOAs).

Abstract: A semiconductor optical amplifier device includes an active layer, an n-type InP substrate, an n-type InP clad layer, a p-type InP clad layer, p-electrodes and n-electrodes. The active layer is made of, e.g., InGaAsP, and includes a saturable absorption region and optical amplification regions. A common modulated current is injected into each optical amplification region through the p-electrode. A modulated current is injected into the saturable absorption region through the p-electrode independently of the optical amplification region. The active layer receives injection light produced by adding additional noise light to an externally applied light signal, and emits output light produced by amplifying the injection light.

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.

Abstract: An electroabsorption (EA) duplexer in which an optical amplifier, a photodetector, and an optical modulator are monolithically integrated to obtain a high radio frequency (RF) gain in radio-over fiber (RoF) link optical transmission technology is provided. The EA duplexer includes a substrate, a separation area, an optical detection/modulation unit, and an optical amplification unit. The separation area includes a first epitaxial layer formed of at least one material layer on the substrate. The first epitaxial layer functions as a first optical waveguide. The optical detection/modulation unit includes a second epitaxial layer formed of at least one material layer on the first epitaxial layer to detect and modulate an optical signal. The second epitaxial layer functions as a second optical waveguide. The optical amplification unit includes the second optical waveguide and a third epitaxial layer formed of at least one material layer on the second epitaxial layer to amplify an optical signal.

Abstract: Disclosed herein is an apparatus and method for implementing an all-optical OR logic gate. The apparatus includes an optical pulse generator, a Mode-Locked Fiber Laser (MLFL), a first optical splitter, a first optical delay line means, an optical control means, a first optical coupler, a second optical splitter, a second optical delay line means, a third optical splitter, an Erbium Doped Fiber Amplifier (EDFA), a Semiconductor Optical Amplifier (SOA), a second optical coupler, and an optical analyzer. The first optical splitter divides light output from the MLFL. The first and second optical delay line means acquire time delay. The optical control means controls intensity and polarization of the light. The first optical coupler generates the first input signal pattern as a probe signal. The second optical splitter divides light output from the first optical coupler. The third optical splitter divides the second input signal pattern.

Abstract: A broadband light source is disclosed. The broadband light source includes a semiconductor optical amplifier for generating and amplifying light of a broadband wavelength, the amplifier having a first end and a second end and a mirror spaced from the second end of the semiconductor optical amplifier to reflect the light, which is provided by the semiconductor optical amplifier, back to the semiconductor optical amplifier, wherein the semiconductor optical amplifier amplifies the light reflected from the mirror and outputs the amplified light to the first end of the semiconductor optical amplifier. The light source further including at least one lens system to converge light passing through the amplifier ends.

Abstract: A multi-wavelength light source includes a substrate, a fabry-perot laser laminated on the substrate that is operated by driving current below a predetermined threshold current to generate multi-wavelength light including a plurality of peaks whose wavelengths and spacing are identical to these of WDM channels. A semiconductor optical amplifier (SOA) is laminated on the substrate in an arrangement such that a slant surface of the SOA is opposed to a side surface of the fabry-perot laser, which serves to thereby amplify the multi-wavelength light output from the fabry-perot laser. The semiconductor optical amplifier is driven in a gain saturation state to reduce the relative intensity of noise in the channels of the multi-wavelength light that are simultaneously amplified.

Abstract: A laser system, such as a master oscillator/power amplifier system, comprises a gain medium and a stimulated Brillouin scattering SBS mirror system. The SBS mirror system includes an in situ filtered SBS medium that comprises a compound having a small negative non-linear index of refraction, such as a perfluoro compound. An SBS relay telescope having a telescope focal point includes a baffle at the telescope focal point which blocks off angle beams. A beam splitter is placed between the SBS mirror system and the SBS relay telescope, directing a fraction of the beam to an alternate beam path for an alignment fiducial. The SBS mirror system has a collimated SBS cell and a focused SBS cell. An adjustable attenuator is placed between the collimated SBS cell and the focused SBS cell, by which pulse width of the reflected beam can be adjusted.

Abstract: The present invention provides a polarization dependency-free, gain-saturated high function semiconductor optical amplifier and optical module at industrially low cost. The gist of the present invention is to structurally separate the optical signal propagating waveguide from another optical waveguide which serves as a lasing optical cavity for optical amplification in such a manner that the two optical waveguides are formed in the same plane but not parallel to each other.

Abstract: The invention is in the field of distributed Raman amplification for digital and analog transmission applications and other applications, e.g., instrumentation and imaging applications, including HFC-CATV applications. In particular, the invention uses a high power broadband source of amplified spontaneous emission (ASE) as the Raman pump source for improved system performance. The invention also includes methods for constructing such a high-power broadband Raman pump.

Abstract: An optical device comprises a semiconductor structure including first and second ridge waveguides, each waveguide comprising a ridge extending across a surface of the semiconductor structure. The ridge of the first waveguide has a first height above a first region of the surface, and the ridge of the second waveguide has a second, greater, height above a second region of the surface. The semiconductor structure includes a multimode interference (MMI) region situated between the first and second ridge waveguides, which provides a transition between them. At least a part of the MMI region is tapered in width and/or at least a part of the first and/or second ridge waveguide is tapered in width in a direction extending away from the MMI region.

Abstract: A laser source for generating amplified and filtered optical output, comprising a VCSEL, a power optical amplifier, and a filter. A laser source for generating amplified and filtered optical output, comprising a first mirror and a second mirror forming a cavity, an optical amplifier disposed in the cavity, and filter means for filtering ASE generated and amplified by the optical amplifier. A system for generating amplified and filtered optical output, comprising an optical platform having electrical connections and a fiber optic connection, a VCSEL configured to generate seed light, an optical amplifier configured to receive and amplify seed light to generate power boosted ASE and a filter configured to reduce background noise from the power boosted ASE. A method of generating optical output having high optical power with high spectral fidelity, comprising generating seed light, amplifying seed light, and filtering the amplified optical output to reduce background noise.

Abstract: A semiconductor optical integrated circuit includes: a semiconductor substrate; a light reflecting portion and a gain region, on the semiconductor substrate; a first optical waveguide connecting the reflecting portion and the gain region; and a second optical waveguide in conjunction with the first optical waveguide and having a larger optical absorptance than the first optical waveguide.

Abstract: A gain-clamped semiconductor optical amplifier includes a semiconductor optical amplifier for amplifying an inputted optical signal and outputting amplified spontaneous emission light, the amplified spontaneous emission light consisting of a first portion and a second portion, the first portion having a wavelength range to be amplified. The amplifier further includes a wavelength selective reflector for allowing the first portion of the amplified spontaneous emission light to pass through the wavelength selective reflector and reflecting the second portion of the amplified spontaneous emission light again to the semiconductor optical amplifier, thereby clamping the gain of the amplifier.

Abstract: A broad-band light source using a semiconductor optical amplifier is provided. The broad-band light source includes the semiconductor optical amplifier including an active layer serving as a gain area, an under-cladding layer, an over-cladding layer, and antireflection layers formed at both ends of the active layer; and a reflector, located at the outside of the semiconductor optical amplifier, for reflecting light outputted from the semiconductor optical amplifier so that the reflected light is inputted back to the active layer so as to minimize gain ripple of the semiconductor optical amplifier.

Abstract: An active layer contains quantum structures. The active layer amplifies light propagating therein while current is injected therein. Electrodes are provided for sections of the active layer sectionalized along a light propagation direction. The electrodes inject different currents into the sections. Current is supplied to the electrodes in such a manner that a first current density is set to one section of the active layer and a second current density is set to another section. The first current density is lower than that at a cross point and the second current density is higher than that at the cross point. The cross point is a cross point between gain coefficient curves at least two different transition wavelengths of the quantum structures. The curves are drawn in a graph showing a relation between a density of current injected into the active layer and a gain coefficient of the active layer.

Abstract: Disclose is a photonic crystal structure comprises atomic dielectric pillars having a refractive index distribution and a structure which are both mirror-symmetrical in a thicknesswise direction of the photonic crystal. The atomic pillars are arrayed in a two-dimensional lattice pattern to form a dielectric pillar lattice. The dielectric pillar lattice is disposed within a surrounding dielectric having a uniform or substantially uniform refractive index distribution. An organic resin which serves as part of surrounding dielectric is disposed in an asymmetrical position in a thicknesswise direction of the photonic crystal.

Abstract: A semiconductor optical amplifier (SOA) has an overall gain that is substantially polarization independent, i.e., less than 1 dB difference between transverse electric (TE) and transverse magnetic (TM) gain. The SOA includes a residual cladding layer having different thicknesses over different portions of the gain section. Over a first portion of the gain section, the residual cladding layer is thinner than over a second portion of the gain section. This results in the first portion providing more gain to optical energy having a TE polarization state than optical energy having a TM polarization state. In the second portion of the gain section, however, more gain is provided to optical energy having a TM polarization state than energy having a TE polarization state. The resulting gain differences can be designed to offset one another so that the output has a gain that is substantially polarization independent.

Abstract: An optical device having a semiconductor optical amplifier (SOA) coupled to an optical filter, which device may be used for optical performance monitoring. One embodiment of the invention provides an optical regenerator/monitor (RM), in which an SOA is used both for optical regeneration of a communication signal applied to the RM and for evaluation of the quality of that signal. The RM has (i) a 2R regenerator, which includes the SOA and an optical filter, and (ii) a relatively simple signal processor configured to receive optical signals from two or more sampling points located at the regenerator. In one configuration, the processor evaluates the quality of the communication signal by comparing optical power tapped from the input and output of the regenerator. The RM, so configured, can be used, for example, to monitor chromatic dispersion and/or optical noise in the communication signal.

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: A method and apparatus for transferring information of an optical information-bearing signal from a first wavelength to a second wavelength. The method is implemented in an all-optical wavelength converter circuit which includes a laser diode in communication with a polarization controller. An information-bearing signal having a first wavelength is input to the circuit. A polarization controller adjusts the polarization of the information-bearing signal. The laser diode receives the polarization-adjusted information-bearing signal and generates a converted information-bearing signal by transferring the information of the polarization-adjusted information-bearing signal from the first wavelength to the second wavelength. The polarization controller receives the converted information-bearing signal from the laser diode, and polarizes the converted information-bearing signal.

Abstract: The optical amplifying device comprises a DFB laser 22 formed on an n type InP substrate 10, for outputting control light; a symmetrical Mach-Zehnder interferometer 12 formed on the n type InP substrate 10 and including 3 dB optical couplers 14, 16 having 2 input ports and 2 output ports, and optical waveguides 24a, 24b which optically interconnect the output port of the 3 dB optical coupler 14 and the input port of the 3 dB optical coupler 16; and SOAs 24a, 24b respectively formed in the optical waveguides 24a, 24b.

Abstract: A semiconductor optical amplifier (SOA) has an overall gain that is substantially polarization independent, i.e., less than 1 dB difference between transverse electric (TE) and transverse magnetic (TM) gain. The SOA includes gain and polarization rotation functions integrated onto a single substrate. According to one exemplary embodiment, a passive polarization rotation section is disposed between two active gain sections.

Abstract: The present invention provides a polarization dependency-free, gain-saturated high function semiconductor optical amplifier and optical module at industrially low cost. The gist of the present invention is to structurally separate the optical signal propagating waveguide from another optical waveguide which serves as a lasing optical cavity for optical amplification in such a manner that the two optical waveguides are formed in the same plane but not parallel to each other.

Abstract: A folded cavity semiconductor optical amplifier is provided that includes a first mirror disposed on a substrate of semiconductor material and an active region formed thereon consisting of an optical cavity with a gain medium. The optical cavity being disposed adjacent the first mirror. A second mirror is formed and disposed on the active region on a surface opposite the first mirror. The active region of the amplifier includes input and output portions formed in one or both mirrors. The input and output portions formed from layers of reduced reflectivity relative to the first or second mirror and a longitudinal waveguide integral to the optical cavity connecting the input and output portions to allow for light to be amplified to enter at the input port, travel through the vertical cavity and longitudinal waveguide, and exit as amplified light at the output portion of the waveguide structure.

Abstract: The present invention relates to an apparatus and a method for realizing all-optical NOR logic device using the gain saturation characteristics of a semiconductor optical amplifier(SOA). More particularly, the invention relates to a 10 Gbit/s all-optical NOR logic device among all-optical logic devices, in which a signal transmitted from a given point of an optical circuit such as an optical computing circuit is used as a pump signal and a probe signal.

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.