Abstract: An optical latch based on a lasing semiconductor optical amplifier is disclosed. The optical latch is configured to achieve one or more stable states in response to the input of predetermined signals at a “SET” input and a “RESET” input of the optical latch. The optical latch includes first and second LSOAs, each of which is configured to receive a pump input and generate an amplifier output. Each LSOA is also associated with a respective combiner and splitter. The combiner associated with each LSOA combines an input signal from the “SET” or “RESET” input, as applicable, with a signal received from the splitter of the other LSOA and the resulting combined signal is then input to the LSOA. Each splitter receives a ballast laser output from the associated LSOA, which is then split into two signals, namely, an input to the combiner of the other LSOA and an output signal.

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

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

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

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

Abstract: Optical regenerators are disclosed, one of which includes a splitter having an input signal input, and first and second outputs, where the first output is connected to a first input of an optical flip-flop that also includes an output. A first OAND gate includes a first input connected to the output of the optical flip-flop, and also includes a second input and an output. A second OAND gate has a first input connected to the second output of the splitter, and includes a second input and an output. A variable oscillator having an input and an output is arranged so that the output is connected to the second input of the second OAND gate and to the second input of the first OAND gate. Finally, a feedback controller has an input connected to the second OAND gate output, and an output connected to the variable oscillator input.

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

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

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

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

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

Abstract: Optical logic circuits are based on lazing semiconductor optical amplifiers, such as vertical lazing semiconductor optical amplifiers. For example, one or more VLSOAs with selected depletion thresholds are combined to form various optical logic devices.

Abstract: An optical transistor is disclosed that provides a fast switching time, an amplified gain, and isolation. The optical transistor receives a small optical input signal at an optical base port, generates an amplified replica at an optical emitter port, and generates an inverted replica on a vertical light at an collector port. One embodiment of the optical transistor is implemented with a vertical lasing semiconductor optical amplifiers (VLSOA), wherein the ballast light is used a signal for the collector port.

Abstract: 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. In response to the signal amplification, a ballast laser signal is output through a substrate of the lasing SOA. This ballast laser signal is indicative of the optical signal power. 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 signal may determine the power of the electrical signal and the gain across the lasing SOA. A gain control circuit may adjust the gain across a tunable-gain lasing SOA or multi-stage optical amplifier in order to optimize the optical signal's strength. The electrical signal power and lasing SOA gain may be transmitted to a terminal to display this information or a warning may be generated when certain criteria are met.

Abstract: Optical regenerators are disclosed, one of which includes a splitter having an input signal input, and first and second outputs, where the first output is connected to a first input of an optical flip-flop that also includes an output. A first OAND gate includes a first input connected to the output of the optical flip-flop, and also includes a second input and an output. A second OAND gate has a first input connected to the second output of the splitter, and includes a second input and an output. A variable oscillator having an input and an output is arranged so that the output is connected to the second input of the second OAND gate and to the second input of the first OAND gate. Finally, a feedback controller has an input connected to the second OAND gate output, and an output connected to the variable oscillator input.

Abstract: 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.

Abstract: An optical 2R/3R regenerator is described. One or more LSOAs are used as part of the optical 2R/3R register.

Abstract: Early warning failure detetection is provided for an optical amplifier. The optical amplifier is based on a lasing semiconductor optical amplifier, which generates a ballast laser signal in addition to the amplified optical signal. The ballast laser signal exhibits a wavelength shift before failure and this wavelength shift is used as the basis for an early warning of future failure of the amplifier.

Abstract: A multi-stage lasing semiconductor optical amplifier (SOA) device amplifies an optical signal. The multi-stage SOA includes at least two SOA stages coupled in series. Each SOA stage includes a semiconductor gain medium and a laser cavity including the semiconductor gain medium. The medium is pumped above a lasing threshold for the laser cavity, which clamps the gain of the medium. An optical signal propagating through the medium is amplified by the gain-clamped medium. The SOA stages are characterized by a design parameter which varies from stage to stage. In a preferred embodiment, the design parameter includes a noise figure and a saturable power, with both parameters increasing as the optical signal propagates from stage to stage. As a result, the multi-stage SOA can achieve better noise performance and higher power outputs compared to comparable SOAs of constant noise figure and saturable power.

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