Fujitsu Corporation

Masaji Noguchi

Yutaka Kai

Tomohiro Ueno

Setsuo Yoshida

Hideyuki Miyata

Toshihisa Kyouno

Goji Nakagawa

Yasuhiko Aoki

Hiroyasu Ito

A semiconductor optical amplification module that can suppress ringing without increasing power consumption or circuit size or inhibiting high-speed operation. A semiconductor optical amplifier outputs an optical signal inputted according to driving current outputted from a drive circuit. A diode is connected in parallel with the semiconductor optical amplifier. As a result, it becomes possible to suppress ringing without connecting a large resistor to the drive circuit.

Semiconductor optical amplification module, optical matrix switching device, and drive circuit

An optical-switch drive circuit including a driver unit that generates, in response to a control signal, an on/off signal for driving a semiconductor optical amplifier gate switch, and a buffer unit having a high input impedance and connected between an output terminal outputting the on/off signal and the semiconductor optical amplifier gate switch. In the optical-switch drive circuit the buffer unit may include a high-resistance voltage divider that is connected with the output terminal, and an operational amplifier that buffers, and provides to the semiconductor optical amplifier gate switch, a divided voltage of the voltage divider.

Optical-switch drive circuit and method thereof

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.

Driving circuit of optical gate switch

A drive circuit includes a first transistor that is controlled to be in on or off state in response to a control signal, and outputs, in on state, a positive current which is input from a first operational amplifier connected with a drain of the first transistor to a semiconductor optical amplifier; and a second transistor that is connected with a source of the first transistor, and is in inverse on or off state to the state of the first transistor. The drive circuit also includes a negative voltage circuit that is connected to a source of the second transistor, and outputs, when the second transistor is in on state, a negative current to the semiconductor optical amplifier.

Drive circuit and optical switch

A non-inverting amplifier circuit is disclosed that includes an operational amplifier and a preemphasis circuit connected between the operational amplifier and a signal source. The preemphasis circuit is configured to compensate for the internal delay of a load connected to the output of the operational amplifier by emphasizing a high-frequency component of a signal fed from the signal source.

Non-inverting amplifier circuit and optical switch driver circuit

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.

Semiconductor optical amplifier gate switch drive circuit, semiconductor optical amplifier gate switching device, and optical cross connect

An optical communication apparatus for controlling the operating point of an optical modulation unit appropriately. An adding unit adds a bias voltage and a pilot signal. An optical modulation unit modulates light by an electrical signal, performs further modulation by a signal from the adding unit, and outputs an optical signal. A monitor unit monitors the level of the optical signal and outputs a monitor signal. A reference signal output unit outputs a reference in phase with the pilot signal contained in the monitor signal. A synchronous pilot-signal detection unit performs synchronous detection of the monitor signal by using the reference. A synchronous noise detection unit extracts noise from the monitor signal and performs synchronous detection of the noise by using the reference. A control signal output unit subtracts the synchronous detection value of the noise from that of the monitor signal, and outputs a control signal.

Optical communication apparatus

An AOTF control apparatus, which applies an RF signal to an AOTF to allow a selected light to pass through the AOTF, includes: a first calculating unit calculating a relationship between a frequency of the RF signal and a wavelength of the selected light based on a frequency of the RF signal that allows a reference light to pass through the AOTF; and a second calculating unit calculating a relationship between a power of the RF signal and an attenuation amount of the selected light based on an input/output power of the reference signal at the input/output of the AOTF.

Acousto-optic tunable filter control apparatus automatically adjusting frequency and power of radio frequency signal

A method of wavelength selection control is disclosed. The method includes detecting reference RF frequencies by varying the frequency of a RF signal supplied to a reference acousto-optic tunable filter with the reference RF frequencies corresponding to reference wavelengths of reference signals input to the tunable filter, performing tracking to optimize the reference RF frequencies, calculating dependent RF frequencies corresponding to wavelengths of WDM transmission signals and recording the calculated dependent RF frequencies in a first register, repeating the above when a request of wavelength selection is not received, when a request of wavelength selection is received, selecting one of the dependent RF frequencies corresponding to the requested wavelength and recording the selected dependent RF frequency in a second register for use of an acousto-optic tunable filter at a port in operation, and generating and supplying a RF signal having the selected dependent RF frequency to the acousto-optic tunable filter.

Method of wavelength selection control and wavelength variable filter device

A drop-type AOTF is used as a configuration for removing from a through signal an optical signal having the same wavelength as that of an optical signal to be added. To the drop-type AOTF, RF signals are input to always select all of wavelengths, and an RF signal is not input for a wavelength desired to be rejected. As a result, the optical signal having the wavelength for which the RF signal is stopped is not selected by the drop-type AOTF, and cannot pass through. Since there is only one RF signal whose input is stopped, a 'drawing effect' does not occur, and control of an optical add/drop device is simplified. Additionally, since high-speed switching can be made, and a wavelength to be added can be varied, restrictions are not imposed on a network configuration.

Optical add/drop device

A radio-frequency-signal generator generates an RF signal. An optical monitor monitors a first intensity of a reference signal and a second intensity of a drop signal. A reference-frequency determining unit determines, based on the first intensity, a first frequency of an RF signal that causes the AOTF to output the reference signal. A temperature detecting unit detects a temperature of the AOTF. A frequency calculating unit calculates a second frequency of an RF signal that causes the AOTF to output a drop signal of a desired wavelength. A control unit controls the RF-signal generator to generate the RF signal of the second frequency calculated.

Growing community of inventors

Kawasaki, Japan

Masaji Noguchi