Abstract: An optical module, which is arranged in an optical transmission path, includes an optical amplifying unit configured with a semiconductor, wherein the optical amplifying unit amplifies light input from the optical transmission path, and an optical element configured with a semiconductor, wherein the optical element propagates the light amplified by the optical amplifying unit to the optical transmission path.

Abstract: A driving circuit of a semiconductor optical amplifier type gate switch constituting a matrix optical switch is provided with an operation amplifier into which a driving signal is input and from which a current corresponding to the driving signal is output, an inductance element provided at an output terminal of the operation amplifier, and a circuit composed of a diode element and a resistor element connected in parallel and provided between the inductance element and the semiconductor optical amplifier.

Abstract: A method provides and/or controls an optical signal, wherein a control signal and at least one data signal are optically processed into a combined signal of substantially constant optical power. The level of the at least one data signal is substantially maintained within the combined signal. In addition, an according device is provided. Suitable for compensation of Raman tilt in WDM communication systems.

Abstract: The invention relates to pulsed optical sources formed of a source of seed optical radiation, a pulsed optical amplifier for pulsing the seed optical radiation, and an output optical port for outputting a pulsed optical signal produced by the pulsed optical amplifier. An optically isolating element such as an optical circulator is provided in the optical path between the optical seed source and the pulsed optical amplifier.

Abstract: In a Wavelength-Division-Multiplexed Passive Optical Network (WDM-PON) utilizing a conventional downstream optical signal reusing method, there is an inventory problem that different optical transmitter types need to be provided for the operation, management, replacement, etc. of a system. A WDM-PON system according to the present invention, includes: a seed light (SL) unit generating a seed light whose wavelength intervals and center wavelengths are adjusted using at least one seed light source; an optical line terminal (OLT) receiving the wavelength-multiplexed seed light from the seed light unit, transmitting a downstream optical signal to a subscriber of the WDM-PON, and receiving a upstream optical signal from the subscriber; and an optical network unit (ONU) receiving the downstream optical signal from the OLT, flattening and modulating the downstream optical signal with upstream data so that the downstream optical signal is reused for carrying upstream data.

Abstract: An integrated semiconductor optical-emitting device includes a surface-emission laser diode and an EA-type semiconductor optical modulator integrated commonly on a GaAs substrate in a direction perpendicular to the GaAs substrate.

Abstract: Unidirectionality of lasers is enhanced by forming one or more etched gaps (78, 80) in the laser cavity. The gaps may be provided in any segment of a laser, such as any leg of a ring laser, or in one leg (62) of a V-shaped laser (60). A Brewster angle facet at the distal end of a photonic device coupled to the laser reduces back-reflection into the laser cavity. A distributed Bragg reflector is used at the output of a laser to enhance the side-mode suppression ratio of the laser.

Abstract: A semiconductor optical amplifier includes a semiconductor substrate; an active layer that includes a first region and a second region formed over the semiconductor substrate; and a reflection part that is formed along the second region and includes a first portion that reflects a first wavelength light and a second portion that reflects a second wavelength light with an optical gain lower than an optical gain of the first wavelength light; wherein, the first portion is formed closer to the first region side than the second portion.

Abstract: A semiconductor surface emitting optical amplifier chip utilizes a zigzag optical path within an optical amplifier chip. The zigzag optical path couples two or more gain elements. Each individual gain element has a circular aperture and includes a gain region and at least one distributed Bragg reflector. In one implementation the optical amplifier chip includes at least two gain elements that are spaced apart and have a fill factor no greater than 0.5. As a result the total optical gain may be increased. The optical amplifier chip may be operated as a superluminescent LED. Alternately, the optical amplifier chip may be used with external optical elements to form an extended cavity laser. Individual gain elements may be operated in a reverse biased mode to support gain-switching or mode-locking.

Abstract: An active layer has a quantum well structure formed of InGaAsP, and includes a saturable absorption region and optical amplification regions. To the saturable absorption region, a voltage is applied through a p-electrode, independent from the optical amplification region. To the optical amplification regions, currents are injected through p-electrodes, respectively. An input light Pin entering through a plane of incidence is generated by adding optical noise of white noise, to a light signal assuming binary optical intensity of “1” or “0”. The saturable absorption region and optical amplification regions are formed satisfying conditions that a waveform converting element provides a semiconductor laser of bistable state.

Abstract: A polarization-independent SOA is provided which uses an InP substrate (11) as a semiconductor substrate and uses GaInNAs having introduced tensile strain as an active layer (14). With this configuration, the polarization independence is achieved by introducing the tensile strain, and high saturation optical output power is realized by reducing the film thickness of the active layer (14) as well as the gain peak wavelength is increased by reducing the band gap of the active layer (14) through use of GaInNAs made by adding nitrogen (N) to GaInAs as a material of the active layer (14) so as to achieve high gain especially in C-band and L-band even when band filling exits at the time of injecting a high current into the active layer (14).

Abstract: A polarization-independent SOA having an InP substrate used as a semiconductor substrate, and an active layer taking an MQW structure formed of a barrier layer made of GaInAs with tensile strain applied thereto and a well layer made of GaInNAs with no strain applied thereto alternately laminated in a plurality of layers, here, four layers of the well layer and five layers of the barrier layer are alternately laminated, is proposed.

Abstract: An optical amplifier includes a semiconductor optical amplifier which has a gain that changes in accordance with a wavelength of input light and which generates a noise light power having different levels in accordance with a drive current, a detector that detects an optical power branched from output light of the semiconductor optical amplifier, and a controller that controls supply of the drive current based on the optical power such that an output light power of the semiconductor amplifier is a sum of a target signal light power and the noise light power.

Abstract: An optical switch using a Michelson interferometer and differential onset of optical nonlinearity. Modulation of optical signals can occur at speeds that exceed that of electronic devices.

Abstract: A vertical cavity surface emitting laser (VCSEL) is described using a sub-wavelength grating (SWG) structure that has a very broad reflection spectrum and very high reflectivity. The grating comprises segments of high and low refractive index materials with an index differential between the high and low index materials. By way of example, a SWG reflective structure is disposed over a low index cavity region and above another reflective layer (either SWG or DBR). In one embodiment, the SWG structure is movable, such as according to MEMS techniques, in relation to the opposing reflector to provide wavelength selective tuning. The SWG-VCSEL design is scalable to form the optical cavities for a range of SWG-VCSELs at different wavelengths, and wavelength ranges.

Abstract: A wavelength-variable light source according to the present invention includes 2×2 3-dB directional coupler 3, closed loop-type optical circuit 5, at least two resonators 1 and 2, and optical amplifier 4. The closed loop-type optical circuit 5 is formed by connecting ends of the two output paths of 3-dB directional coupler 3. The resonators 1 and 2 have different resonance wavelength periods. One end of optical amplifier 4 is optically connected to one input path end 6 of 3-dB directional coupler 3. Lasing light is output from the other end of the optical amplifier 4. A non-reflecting structure is formed at the other input path end 7 of the 3-dB directional coupler. The wavelength-variable light source configured as described above includes an element configured to vary the resonance wavelength of the resonator 1 or 2.

Abstract: The heterostructures are used for creation of semiconductor injection emission sources: injection lasers, semiconductor amplifying elements, semiconductor optical amplifiers that are used in fiber optic communication and data transmission systems, in optical superhigh-speed computing and switching systems, in development of medical equipment, laser industrial equipment, frequency-doubled lasers, and for pumping solid-state and fiber lasers and amplifiers.

Abstract: Included are: an active layer provided between an upper multilayer film reflecting mirror and a lower multilayer film reflecting mirror formed on a GaAs substrate and formed of a periodic structure of a low-refractive-index layer formed of AlxGa1-xAs (0.8?x?1) and a high-refractive-index layer formed of AlyGa1-yAs (0?y?x), at least one of the low-refractive-index layer and the high-refractive-index layer being of n-type; and a lower electrode provided between the lower multilayer film reflecting mirror and the active layer and configured to inject an electric current into the active layer.

Abstract: An IR laser source providing light in the IR spectrum, the laser source comprising a pump laser operating at a frequency equivalent to wavelength shorter than 2 ?m and at a predetermined power, and an optic fiber coupled to the pump laser. The optic fiber has at least a section of a hollow core photonic crystal fiber, the at least a section of hollow core photonic crystal fiber being designed to have at least a passband in the IR spectrum and being filled with a molecular gas for triggering at least one Stoke's shift in the light entering the at least a section of hollow core photonic crystal fiber for the particular power of the pump laser, the at least one Stoke's shift be selected to cause the light entering the at least a section of hollow core photonic crystal fiber to shift in frequency into the passband in the IR spectrum of the hollow core photonic crystal fiber.

Abstract: A semiconductor device including a semiconductor optical amplifier in which a photodetector is integrated without causing power loss at a low cost. The semiconductor device includes a semiconductor substrate, a semiconductor optical waveguide, at least partly capable of functioning as a semiconductor optical amplifier, to guide signal light, and a photodetector provided in a region other than a region where the semiconductor optical waveguide is provided, wherein the semiconductor optical waveguide and the photodetector are integrated on the semiconductor substrate.

Abstract: A semiconductor optical amplifier includes a semiconductor substrate; an optical waveguide that includes an active layer formed on the semiconductor substrate; and a wavelength selective reflection film that is formed on an end face where signal light is incident on the optical waveguide the wavelength selective reflection film allows transmission of the signal light, and reflects light of any wavelength other than the signal light.

Abstract: An optical semiconductor device includes: a beam splitter that splits an input optical axis into a first split axis having a first split angle and a second split axis having a second split angle larger than the first split angle; a first unit that is located on the first split axis of the beam splitter and has one or more optical components, an interval between a more distant end of the first unit and the beam splitter having a first length; a second unit that is located on the second split axis of the beam splitter and has one or more optical components, an interval between a more distant end of the second unit and the beam splitter having a second length larger than the first length; and an optical semiconductor element that has a first outputting end having a first output axis coupled optically to the input optical axis of the beam splitter, a second outputting end having a second output axis, and optical gain, the optical semiconductor element being inclined so that the second output axis is arranged away

Abstract: A drive circuit is provided for a semiconductor optical amplifier type gate switch includes a first transmission path and a second transmission path. The first transmission path includes a common first sub-path between a signal source and a first node; and an individual second sub-path for each of a plurality of operational amplifiers between the first node and a corresponding one of the operational amplifiers. The second transmission path includes an individual third sub-path between each of the operational amplifiers and a second node; and a common fourth sub-path between the second node and the semiconductor optical amplifier type gate switches. Transmission delay times of all the individual second sub-paths are equal, and transmission delay times of all the individual third sub-paths are equal.

Abstract: An on-chip amplifier includes first element that curtails the velocity of an incoming light to the amplifier. A second element is doped so as to make the frequency of the incoming light equal to the electron frequency in order to allow for electron-photon wave interaction, so that when current flows through the amplifier, electron power is transferred to the incoming light, resulting in amplification of the incoming light.

Abstract: A Reflective Semiconductor Optical Amplifier (RSOA) for compensating for light loss in an optical link, an RSOA module for improving polarization dependency using the RSOA, and a Passive Optical Network (PON) for increasing economical efficiency and practical use of a bandwidth using the RSOA are provided. The PON includes a central office comprising a plurality of optic sources transmitting a downstream signal and a plurality of first receivers receiving an upstream signal; at least one optical network terminal (ONT) including a second receiver receiving the downstream signal and an RSOA which receives the downstream signal, remodulates the downstream signal into the upstream signal, and transmits the upstream signal in loopback mode; and a remote node interfacing the central office with the ONT. The upstream signal and the downstream signal are transmitted between the remote node and the ONT via a single optical fiber. The remote node includes an optical power splitter at its port connected to the ONT.

Abstract: An apparatus including a semiconductor optical amplifier configured to amplify an input optical signal, and a controller configured to supply preheat current to the semiconductor optical amplifier when the input optical signal is not input to the semiconductor optical amplifier.

Abstract: An integrated photonic circuit includes waveguides (12-19) and other photonic components. The photonic circuit has a first part (1) and a second part (2), the first part and the second part being connected to a mirror in the form of a half 2×2 multimode interferometer (MMI) (32), which comprises solely one half MMI (31) in a longitudinal direction, the half MMI (32) having two ports (33, 34) and being arranged to reflect half of the light that is incident on one of the ports to one port and transmit half of the incident light to the second port, and the free surface (35) of the half MMI (32) having been treated with a highly reflective material.

Abstract: A semiconductor-based Raman ring amplifier is disclosed. A method according to aspects of the present invention includes directing a pump optical beam having a pump wavelength and an input pump power level from an optical waveguide into a ring resonator. The optical waveguide and ring resonator are comprised in semiconductor material. A signal optical beam having a signal encoded thereon at a signal wavelength is directed from the optical waveguide into the ring resonator. The pump optical beam is resonated within the ring resonator to increase a power level of the pump optical beam to a power level sufficient to amplify the signal optical beam via stimulated Raman scattering (SRS) within the ring resonator. A free carrier concentration in the optical waveguide and the ring resonator is reduced to reduce attenuation of the pump optical beam and the signal beam.

Abstract: A semiconductor optical element has an active layer including quantum dots. The density of quantum dots in the resonator direction in a portion of the active layer in which the density of photons is relatively high is increased relative to the density of quantum dots in a portion of the active layer in which the density of photons is relatively low.

Abstract: A multi-band hybrid amplifier is disclosed for use in optical fiber systems. The amplifier uses Raman laser pumps and semiconductor optical amplifiers in series to produce a relatively level gain across the frequency range of interest. Multiple Raman pumps are multiplexed before coupling into the fiber. The Raman amplified optical signal may be demultiplexed and separately amplified by the SOAs before re-multiplexing. Gain profiles of the Raman pumps and the SOAs are selected to compensate for gain tilt and to alleviate the power penalty due to cross-gain modulation in the SOAs. The disclosed hybrid amplifier is especially useful in coarse wavelength division multiplexing (CWDM) systems.

Abstract: A Reflective Semiconductor Optical Amplifier (RSOA) for compensating for light loss in an optical link, an RSOA module for improving polarization dependency using the RSOA, and a Passive Optical Network (PON) for increasing economical efficiency and practical use of a bandwidth using the RSOA are provided. The PON includes a central office comprising a plurality of optic sources transmitting a downstream signal and a plurality of first receivers receiving an upstream signal; at least one optical network terminal (ONT) including a second receiver receiving the downstream signal and an RSOA which receives the downstream signal, remodulates the downstream signal into the upstream signal, and transmits the upstream signal in loopback mode; and a remote node interfacing the central office with the ONT. The upstream signal and the downstream signal are transmitted between the remote node and the ONT via a single optical fiber. The remote node includes an optical power splitter at its port connected to the ONT.

Abstract: A multi-band hybrid amplifier is disclosed for use in optical fiber systems. The amplifier uses Raman laser pumps and semiconductor optical amplifiers in series to produce a relatively level gain across the frequency range of interest. Multiple Raman pumps are multiplexed before coupling into the fiber. The Raman amplified optical signal may be demultiplexed and separately amplified by the SOAs before re-multiplexing. Gain profiles of the Raman pumps and the SOAs are selected to compensate for gain tilt and to alleviate the power penalty due to cross-gain modulation in the SOAs. The disclosed hybrid amplifier is especially useful in coarse wavelength division multiplexing (CWDM) systems.

Abstract: A semiconductor optical amplifier for amplifying an optical signal. The amplifier comprises an input for receiving the optical signal and an output for outputting an amplified version of the optical signal. A semiconductor active medium is provided for defining an amplification path extending between the input and the output for amplifying the optical signal as the optical signal propagates along the amplification path. A control means selectively controls the amplified spontaneous emission (ASE) of the semiconductor optical amplifier. The control means is co-operable with the active medium for selectively varying carrier density along the amplification path.

Abstract: Methods and corresponding apparatus for optical amplification in semiconductors, particularly indirect band-gap semiconductors, and most particularly in silicon. A first aspect of the invention employs certain doping elements to provide inter-band-gap energy levels in combination with optical or current-injection pumping. The doping element, preferably a noble metal and most preferably Gold, is chosen to provide an energy level which enables an energy transition corresponding to a photon of wavelength equal to the signal wavelength to be amplified. The energy transition may be finely “adjusted” by use of standard doping techniques (such as n-type or p-type doping) to alter the conduction and valence band energy levels and thereby also the magnitude of the energy transition. A second aspect of the invention relates to the use of a non-homogeneous heat distribution which has been found to lead to optical amplification effects.

Abstract: In an optical transmission system according to one aspect of the present invention, for transmitting a WDM light from a transmission station to a reception station, utilizing a Raman amplifier, the Raman amplifier comprises: an optical amplification medium; a pumping light source generating a plurality of pumping lights having wavelengths different from each other; an optical device introducing the plurality of pumping lights to the optical amplification medium; and control means for controlling the pumping light source, the transmission station sends out a plurality of reference lights having wavelengths at which respective Raman gain obtained by the plurality of pumping lights reach peaks or wavelengths close to the above wavelengths, and the control means controls the plurality of pumping lights based on the optical powers of the plurality of reference lights. Thus, it becomes possible to accurately manage the optical power balance of the WDM light and the optical power of the entire WDM light.

Abstract: A method of modulation terahertz radiation comprising: (A) generating Terahertz radiation by pumping nonequilibrium electrons into a Magnon Gain Medium (MGM), wherein propagation of nonequilibrium electrons in the MGM causes generation of nonequilibrium magnons, and wherein interaction between the nonequilibrium magnons causes generation of the Terahertz radiation; and (B) frequency modulating THz radiation generated in the MGM by applying longitudinal AC magnetic field, or by applying AC electrical field bias.

Abstract: A gain medium and an interband cascade laser, an interband cascade amplifier, and an external cavity laser having the gain medium are presented.

Abstract: An optical amplifier on a silicon platform includes a first doped device layer and a second doped device layer. A gain medium is positioned between the first and second doped device layers. The gain medium comprises extrinsic gain materials so as to substantially confine in the gain medium a light signal and allow the optical amplifier to be electrically or optically pumped.

Abstract: Provided are a semiconductor optical amplifier and an optical signal processing method using the same. The reflective semiconductor optical amplifier includes: an optical signal amplification region operating to allow a downward optical signal incident from the external to obtain a gain; and an optical signal modulation region connected to the optical signal amplification region and generating a modulated optical signal. The downward optical signal is amplified through a cross gain modulation using the modulated optical signal and is outputted as an upward optical signal.

Abstract: A pulse reshaper for reshaping and re-amplifying optical signals in a communications network by adjusting threshold and amplification characteristics of a semiconductor optical amplifier (SOA) having first and second reflective regions optically cooperating at each of an input signal wavelength (?s) and an offset wavelength (?C) proximate the input signal wavelength (?s). In one embodiment, a vertical cavity semiconductor optical amplifier (VCSOA) device, comprising dual mode reflectors optically cooperating at each of an input signal wavelength (?s) and an offset wavelength (?C) proximate the input signal wavelength (?s) to provide thereby non-linear amplification of input signal (?s).

Abstract: At an optical transmission system that uses plural light sources for Raman amplification, even when a failure occurred in a pumping light source in one of the light sources for Raman amplification, the signal light output level and its wavelength characteristic are not deteriorated at the final stage, and the number of components in the system is not made to be large and the cost of the system is not made to be high. This optical transmission system is provided. At an optical transmission system using “n” light sources for Raman amplification, a first to “n?1”th light sources for Raman amplification do not provide spare pumping light sources, and an “n”th light source for Raman amplification provides the spare pumping light sources. When a pumping light source in one of the “n” light sources for Raman amplification had a failure, the spare pumping light source in the “n”th light source for Raman amplification corresponding to the failure occurred pumping light source is worked.

Abstract: In the three-terminal optical signal amplifying device 10, a portion of the neighboring light LS at other wavelength than that of the first wavelength ?1 that is selected from the output light from the element 14 by the optical add drop filter 16, and the control light Lc at the second wavelength ?2 input from the external are together input to the second semiconductor optical amplifying element 18. The output light including the output signal light LOUT at the second wavelength ?2 and the neighboring light at the neighboring wavelength to the second wavelength ?2 that is modulated and controlled by the control light LC in the cross gain modulation is output from the second semiconductor optical amplifying element 18. And the output signal light LOUT at the second wavelength ?2 passes through the wavelength selecting filter 20.

Abstract: A reflective semiconductor optical amplifier (RSOA) and an operating system based on a downstream optical signal reuse method with feed-forward current injection are provided. The RSOA has two active regions and includes a reflecting plane that reflects an input optical signal; and an optical amplifying semiconductor including a rear portion, which is positioned at a side of the reflecting plane and to which a signal having polarity opposite to that of the input optical signal is injected, and a front portion, which is positioned at a side opposite to the side of the rear portion facing the reflecting plane and which the input optical signal is passed though and a signal used to modulate a reflected input optical signal from the reflecting plane to an output optical signal is injected into.

Abstract: A phased array antenna system includes an RF front end, a radome, and an optical calibrator embedded in the radome for enabling in-situ calibration of the RF front end. The optical calibrator employs an optical timing signal generator (OTSG), a Variable Optical Amplitude and Delay Generator array (VOADGA) for receiving the modulated optical output signal and generating a plurality of VOADGA timing signals, and an optical timing signal distributor (OTSD). The in-situ optical calibrator allows for reduced calibration time and makes it feasible to perform calibration whenever necessary.

Abstract: Vertical cavity semiconductor optical amplifiers for various photonic devices including all optical logic gate devices and oscillators, where such devices can be implemented to achieve various advantages, including Boolean inversion at high speeds, low power, workable noise margins for cascadability because of input output isolation, and easy of integration in large arrays.

Abstract: The invention relates to an optical device operating within a wavelength range centred on a reference wavelength (?0) and delivering an output signal, characterized in that it comprises a photonic crystal structure having a semiconductor substrate and at least one layer of semiconductor material having, at least locally, an array of features arranged so as to form a resonant optical cavity, said material of the semiconductor layer being a gallium/indium/phosphorus alloy not exhibiting two-photon absorption within the operating wavelength range of said device.

Abstract: A manufacturing method for an optical semiconductor device, including disposing a semiconductor element that has a polarization dependent gain or polarization dependent loss between optical waveguide modes differing in the direction of polarization, positioning a lens at one end face side of the semiconductor element based on an optical coupling loss between the lens and the semiconductor element, and repositioning the lens based on the polarization dependent gain or the polarization dependent loss of the semiconductor element.

Abstract: Methods and apparatus for providing amplification to coarse wave division multiplexing channels or signals are disclosed. According to one aspect of the present invention, an arrangement that adds gain to a set of signals that may be divided into a first band including signals of lower wavelengths and a second band including signals of higher wavelengths includes a multiplexer, first and second optical amplifiers, and a processing arrangement. The multiplexer multiplexes the set of signals. The first optical amplifier has a first gain peak and provides amplification to the set of signals, while the second optical amplifier has a second gain peak and provides amplification to the second band but not to the first band. The processing arrangement passes the second band from the first optical amplifier to the second optical amplifier, and substantially prevents the first band from passing from the first optical amplifier to the second optical amplifier.

Abstract: A stabilised gain semiconductor optical amplifier (CG-SOA) includes and active waveguide (1) comprising an amplification medium (2), extending in longitudinal (Z), lateral (X) and vertical (Y) directions, and coupled to a laser oscillation structure comprising at least two resonant cavities (13, 14) extending in first (D1) and second (D2) directions which are different from the longitudinal direction (Z) of the active waveguide (1) and arranged in such a way as to permit the establishment of laser oscillations having at least two different relaxation oscillation frequencies.

Abstract: A photonic integrated circuit having a plurality of circuit components, is disclosed, which may include an MMI for splitting signal power passing therethrough among first and second optical pathways coupled to first and second outputs, respectively, of the MMI, thereby directing first and second percentages of the signal power along the first and the second optical pathways, respectively; and a photodetector integrated into the photonic integrated circuit and coupled to said first optical pathway for measuring a signal power level on said first optical pathway.