810results about "Semiconductor amplifier structure" patented technology

This invention relates to opto-electronic systems using semiconductor lasers driven by feedback control circuits that control the laser's optical phase and frequency. Feedback control provides a means for coherent phased laser array operation and reduced phase noise. Systems and methods to coherently combine a multiplicity of lasers driven to provide high power coherent outputs with tailored spectral and wavefront characteristics are disclosed. Systems of improving the phase noise characteristics of one or more semiconductor lasers are further disclosed.

Optical transmitters for radio over fiber systems are disclosed. More particularly, the optical transmitters include optically-injection-locked vertical cavity surface-emitting laser devices (OIL VCSELS). The transmitters include a master laser, at least one slave laser injection-locked by the master laser, and an equalizer / filter unit that enables the ratio of the carrier power to the sideband power in the output signal of the transmitter to be varied and optimized independently of the injection ratio of the transmitter.

An apparatus and method providing a plurality of modulated optical beams from a single layer of semiconductor material. For one example, an apparatus includes a plurality of optical waveguides disposed in a single layer of semiconductor material. Each one of the plurality of optical waveguides includes an optical cavity defined along the optical waveguide. A single bar of gain medium material adjoining the single layer of semiconductor material across the plurality of optical waveguides is included. The gain medium-semiconductor material interface is defined along each of the plurality of optical waveguides. A plurality of optical modulators is disposed in the single layer of semiconductor material. Each one of the plurality of optical modulators is optically coupled to a respective one of the plurality of optical waveguides to modulate a respective optical beam directed from the optical cavity.

Methods, devices and systems for generating ultrashort optical linear chirped pulses with very high power by amplifying the pulses so that their temporal duration is longer than the storage time of the amplifying medium. The additional gain factor is related to the ratio of the storage time to the stretched pulse. A preferred embodiment connects a mode locked laser source that generates optical pulses whose duration is stretched with a chirped fiber Bragg grating. Embodiments include methods, devices and systems causing an extreme chirped pulse amplifier (XCPA) effect in an oscillator.

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.

A novel class of semiconductor light-emitting devices, or “tilted cavity light-emitting devices” is disclosed. The device includes at least one active element, generally placed within a cavity, with an active region generating an optical gain by injection of a current and two mirrors. The device generates optical modes that propagate in directions, which are tilted with respect to both the p-n junction plane and the direction normal to this plane. A light-emitting diode is also disclosed, where the cavity and the mirrors are designed such that transmission of generated optical power within a certain spectral range and within a certain interval of angles to the substrate is minimized. Transmission of optical power within a certain spectral range, which corresponds to the emission range of the light-emitting active medium and within a certain interval of angles out of the device, is optimized to achieve a required output power level.

A forward error correction (FEC) communication device that includes a transmitter photonic integrated circuit (TxPIC) or a receiver photonic integrated circuit (RxPIC) and a FEC device for FEC coding at least one channel with a first error rate and at least one additional channel with a second error rate, wherein the first error rate is greater than the second error rate. The TxPIC chip is a monolithic multi-channel chip having an array of modulated sources integrated on the chip, each operating at a different wavelength, wherein at least one of the modulated sources is modulated with a respective FEC encoded signal. The TxPIC also includes an integrated wavelength selective combiner for combining the channels for transport over an optical link.

The optical transmitter includes a semiconductor laser device, and an optical modulator region optically connected to the semiconductor laser device and having the function of modulating the output light from the semiconductor laser device. The operating temperature of the optical modulator region is changed without changing the oscillation wavelength of the semiconductor laser device.

An optical signal power monitor and regulator comprises: a lasing semiconductor optical amplifier for receiving the optical signal and whose laser output is used to monitor a power level of the optical signal; a monitor circuit which receives the laser output and outputs a monitoring signal; a tunable element for receiving a version of the optical signal and whose level of amplification is adjustable and for outputting an amplified optical signal; and a regulator circuit for receiving the monitoring signal and adjusting the amplification of the tunable optical amplifier depending upon the monitoring signal. The tunable element may comprise a tunable gain-clamped semiconductor optical amplifier. Such an embodiment is capable of automatically regulating the tunable element such that a power level of the amplified optical signal is kept stable. In addition, the monitor circuit may be used to send status information regarding the optical signal to a network management system, which in turn may send to the regulator circuit a managing signal affecting the level of amplification to be applied to the optical signal.

Optical resonator devices and systems enhanced with photoluminescent phosphors and designed and configured to output working light in an edge-emitting fashion at one or more wavelengths based on input / pump light, and systems and devices made with such resonators. The edge-emitting functionality is enabled by providing one or more waveguides that direct light luminesced from the phosphors to one or more edges of the device. In some embodiments, the resonators contain multiple optical resonator cavities in combination with one or more photoluminescent phosphor layers or other structures. In other embodiments, the resonators are designed to simultaneously resonate at the input / pump and output wavelengths. The photoluminescent phosphors can be any suitable photoluminescent material, including semiconductor and other materials in quantum-confining structures, such as quantum wells and quantum dots, among others.

In a laser source, a first optical waveguide includes a gain medium, and a second optical waveguide includes a phase tuner which adjusts a phase value of the phase tuner to specify the wavelength of the laser source. Furthermore, the laser source includes a first ring resonator and a second ring resonator, which, respectively, are optically coupled to the first optical waveguide and the second optical waveguide at opposite ends of the laser source. In particular, coupling wavelengths of the first and second ring resonators may match a wavelength of the optical signal, thereby defining an optical resonance cavity in the laser source and selecting a laser mode of the laser source which is associated with the wavelength. Additionally, the laser source includes an optical amplifier that receives and amplifies the optical signal output from the optical resonance cavity.

A gain-tunable semiconductor optical amplifier (10) includes an amplifying section (38) for amplifying an optical signal (422). A first tunable reflector section (51) and a second tunable reflector section (52) are integrated on opposed sides of the amplifying section (38) to reflect the optical signal at a clamping wavelength and to change an internal gain level to cause a stimulated emission at the clamping wavelength above the internal gain level.

An optical waveguide isolator for use in an optical communication system is disclosed. The optical waveguide isolator comprises a semiconductive light amplifier structure including a semiconductor substrate of first conductivity type having a surface of a layer to be formed thereon, a first cladding layer of first conductivity type formed on the substrate, an active layer formed on the first cladding layer, a second cladding layer of the second conductivity type opposite to first conductivity type, formed on active layer, a first electrode formed on the surface of the semiconductor substrate opposite to the surface to be formed as a layer, and a second electrode formed on the second cladding layer; the first and the second cladding layers and the active layer form an optical waveguide in which the light wave propagates. The semiconductive light amplifier structure further comprises a light absorptive magnetic material layer having light absorption function for the light wave propagating through the optical waveguide. The magnetic material layer is magnetized so as to have the magnetic-field component in the direction which corresponds to the direction where a magnetic vector of the light wave vibrates, the waveguide structure body has a nonreciprocity optical characteristic that effective refractive index changes into the light wave to which the optical waveguide is propagated according to the magnet-optical effect of the light absorptive magnetic material layer according to the direction of propagation, by the effective refractive index change in the nonreciprocity, the attenuation of the first light wave that the optical waveguide is propagated in the first direction caused when the said waveguide is propagated, becomes small more than the attenuation of the second light wave propagated in the second direction opposite to the first direction caused when the said waveguide is propagated.

A wavelength converting member radiates light having a wavelength different from that of laser light introduced into the wavelength converting member. The wavelength converting member has a phosphor layer that contains a phosphor therein. The phosphor layer has a laser light incidence surface capable of receiving the laser light. The wavelength converting member also has a high-refractive layer that is bonded to an opposite surface of the phosphor layer to the laser light incidence surface thereof. A refractive index of the high-refractive layer is higher than a refractive index of the phosphor layer. The high-refractive layer has concaves on at least either the bonding surface where the high-refractive layer is bonded to the phosphor layer or a light extraction surface that is opposite the bonding surface.

Optical logic gates are constructed from Mach-Zehnder Interferometer (MZI) optical circuits. A multi-mode interference (MMI) splitter divides a continuous-wave input into two branches of the interferometer. Each branch has a semiconductor optical amplifier (SOA). When a logic input having a logic-high power level is applied to one of the SOA's, cross-phase modulation occurs in the SOA. The phase shift increases through the SOA. The branch coupled to the logic input has a relative phase shift of pi compared with the other branch. When two branches with the pi phase difference are combined, destructive interference occurs, producing a logic low. An MMI combiner or an equivalent phase shifter is used to combine the two branches. The MMI splitter adds a phase shift of pi / 2 to the upper branch but not to the lower branch, while the MMI combiner also adds pi / 2 shifts.

A photonic integrated circuit (PIC) chip comprising an array of modulated sources, each providing a modulated signal output at a channel wavelength different from the channel wavelength of other modulated sources and a wavelength selective combiner having an input optically coupled to received all the signal outputs from the modulated sources and provide a combined output signal on an output waveguide from the chip. The modulated sources, combiner and output waveguide are all integrated on the same chip.

Disclosed herein is an optical access network system in which the transmission quality of an upstream signal is remarkably improved in an optical access network in which a Reflective Semiconductor Optical Amplifier (RSOA) is used as the light source for each subscriber. The most important characteristics of the present invention are that a Manchester modulation format is used as a modulation format for a downstream signal in an optical access network system in which an RSOA is used as the light source for each subscriber, so that the problem of deterioration of the transmission quality of a remodulated upstream signal, occurring when an RSOA is used as the light source for each subscriber, is solved, and thus the transmission performance of an upstream signal and the power budget performance of the entire system are improved. According to the present invention, an RSOA-based WDM PON system, in which performance at a power budget and the transmission performance of a remodulated upstream signal are improved, can be implemented.

A wavelength converter incorporating an on-chip integrated laser for use in an optical system. The converter includes a first port for receiving an optical input signal such as a WDM signal and providing it to an interferometer, and an output port for outputting a signal which is a wavelength-converted version of the input signal. An optical source or laser is fabricated on the chip substrate on which the interferometer is formed for providing operating power to the interferometer. Power levels of the input signal are maintained by adjusting an on-chip semiconductor optical amplifier that receives the optical input signal and provides the amplified signal to the interferometer. In an alternative embodiment, the on-chip optical source is replaced by an on-chip pre-amplifier for an external laser source.

Disclosed are optical signal transmission apparatus including a reflective gain-clamped semiconductor optical amplifier and optical communication system using the optical signal transmission apparatus, which can improve modulation speed and optical power by effectively suppressing intensity noise of an incoherent light source. The optical signal transmission apparatus comprises a light source; a reflective gain-clamped semiconductor optical amplifier to generate gain-clamped optical signals having a substantially constant output intensity in a gain saturation region; a wavelength division multiplexing apparatus configured to spectrum-slice light from the light source, provide the spectrum-sliced light to the reflective gain-clamped semiconductor optical amplifier, and multiplex optical signals gain-clamped by the reflective gain-clamped optical amplifier. and a circulator for inputting the light generated by the light source to the wavelength division multiplexing apparatus, and outputting the optical signal multiplexed by the wavelength division multiplexing apparatus to a transmission link.

An apparatus comprising a laser transmitter having a first side and a second side, a filter coupled to the first side, a detector coupled to the second side, and a temperature controller coupled to the laser transmitter and the detector. Also disclosed is an apparatus comprising at least one processor configured to implement a method comprising receiving a photocurrent of a backward light from a laser, determining a wavelength shift offset between a wavelength of the output light and a filter transmission peak, and adjusting a temperature of the laser to substantially reduce the wavelength shift and align the wavelength of the output light with the filter transmission peak.

A method of operating an array of laser sources integrated as an array in a single monolithic chip where the steps include designing the laser sources to have different target emission wavelengths so that together they form a spectral emission wavelength grid, coupling outputs from the laser sources to an array of gain / loss elements also integrated on the single monolithic chip, one each receiving the output from a respective laser source; and adjusting the outputs with the gain / loss elements so that the power levels of the laser source array across are substantially uniform.

An optical amplifier module that is insensitive to polarization comprises a first fiber, a second fiber, a semiconductor optical amplifier (SOA), and a polarization dependent loss (PDL) unit. The first fiber provides for optical input to the SOA. The SOA amplifies the optical signal received and outputs the amplified signal. The output of the SOA is optically coupled to the unit. The PDL unit provides polarization dependent loss and the loss is preferably selected to match the polarization dependent gain of the SOA such that when two are coupled there is no overall polarization dependence. The output of the PDL is optically coupled to the fiber for transmission output. The present invention also comprises a method for manufacturing an optical amplifier module that comprises the steps of: determining the polarization dependent gain of an SOA, determining the polarization dependent loss of a plurality of PDL units, selecting a PDL unit such that the polarization dependent loss when coupled to the SOA is reduced, and packaging the SOA and the PDL unit as an optical amplifier module.

A tunable-gain lasing semiconductor optical amplifier comprises a vertical-lasing semiconductor optical amplifier that includes a tunable region which allows the gain of the vertical-lasing semiconductor optical amplifier to be tuned. The tunable region comprises a region whose loss and / or phase may be tuned by adjusting a physical characteristic of the region. For example, the region may comprise a liquid crystal layer whose transmissivity may be adjusted by applying different voltages across the layer to adjust the reflectivity of a cavity mirror, or a cavity mirror whose reflectivity may be adjusted by ion implantation. In an alternative embodiment of this invention, the tunable-gain lasing semiconductor optical amplifier comprises a tunable loss element in series after the gain-clamped semiconductor optical amplifier.

A method of bonding a compound semiconductor on a silicon waveguide is used for attaining a laser above a silicon substrate. While it is essential to attain laser oscillation by injection of a current, since amorphous is formed at the bonding surface of a silicon compound semiconductor, it is difficult to directly inject the current through the silicon waveguide to the compound semiconductor. Further, even when an electrode is formed near the waveguide and the current is injected, since the current is not injected near the silicon waveguide, laser oscillation through the silicon waveguide can not be attained. The problem is solved by forming a structure of laterally injecting a current to the silicon waveguide and concentrating the current near the silicon waveguide in a compound semiconductor. Specific methods includes the following two methods, that is, a method of forming a tunneling junction structure in the compound semiconductor and another method of laterally forming a P-I-N junction to the compound semiconductor.

An optical power combining system. The system may comprise: a means for splitting an optical source into multiple channels; amplifiers in the multiple channels; and waveguide couplers for coherently combining the multiple channels into a single output.

A photonic circuit includes a tunable drop filter arrangement that includes a plurality of resonators. The drop filter arrangement is tuned to remove a selected frequency from an input data stream from a waveguide. A wavelength sensor coupled to the drop filter to monitor the selected frequency to which the drop filter arrangement has been tuned. A tunable laser presents a new signal of a defined frequency indicative of a signal to be added to the input data stream. A modulator coupled to the tunable laser for receiving the new signal and forming a modulated signal. An add filter arrangement coupled to the modulator for receiving the modulated signal and adding the modulated signal to the data stream.

A control apparatus comprises a light monitoring unit for dividing a signal wavelength band into at least a band in which output light power of an optical amplifier tends to decrease at an decrease in the number of signal wavelengths and a band including a gain deviation band, and for monitoring inputted light power for the individual divided bands, a calculation unit for obtaining the number of signal wavelengths in the individual divided bands based on a monitor result, and a target gain correction unit for correcting a target gain based on a result of the calculation. This suppresses a transient variation of signal light level due to SHB or SRS at a high speed with a simple configuration without deteriorating noise characteristic, thus enabling optical amplifiers to be further disposed in a multi-stage fashion, which can lengthen the transmission distance of a transmission system including an optical add / drop unit.

An optical signal power monitoring and control system is described. The system comprises at least one lasing SOA that receives, amplifies, and outputs the optical signal. During the signal amplification, a ballast laser signal is output through a substrate of the lasing SOA. This ballast laser signal is indicative of the output power of the lasing SOA. At least one detector converts the ballast laser signal to an electrical signal and transmits this electrical signal to a power monitor circuit. Using the electrical signal, the power monitor determines the output power of the lasing SOA. A pump control adjusts the rate at which the lasing SOA is pumped in order to change the saturation level of the lasing SOA and its corresponding power output ceiling. According to one embodiment, the power monitor identifies when the lasing SOA is approaching saturation or is saturated. If the lasing SOA is saturated or approaching saturation, the pump control increases its pumping rate causing the saturation level of the lasing SOA to rise. As a result, the lasing SOA is provided protection from saturation.

A variable semiconductor all-optical buffer and method of fabrication is provided where buffering is achieved by slowing down the optical signal using a control light source to vary the dispersion characteristic of the medium based on electromagnetically induced transparency (EIT). Photonic bandgap engineering in conjunction with strained quantum wells (QWs) and quantum dots (QDs) achieves room temperature operation of EIT. Photonic crystals are used to sharpen the spectral linewidths in a quantum well structure due to its density of states and in a quantum-dot structure caused by the inhomogeneity of the dot size, typically observed in state-of-the-art QD materials. The configuration facilitates monolithic integration of an optical buffer with an amplifier and control laser to provide advantages over other material systems as candidates for optical buffers.

An on-chip photodiode is provided in a photonic integrated circuit (PIC) on a semiconductor chip to monitor or check for antireflection qualities of an AR coating applied to the front facet of the semiconductor chip.