Fujitsu Corporation

Fumio Futami

Shigeki Watanabe

Ryou Okabe

Yutaka Takita

Shunsuke Ono

Tomoyuki Kato

An optical amplifier amplifies signal light and includes a pump light source that outputs pump light of a wavelength different from that of the signal light; a combining unit that combines the signal light and the pump light output by the pump light source, to output combined light; an amplifying unit that has non-linear optical media that transmit the combined light to amplify the signal light, the amplifying unit further removing, in the non-linear optical media, idler light generated from the signal light and the pump light, and outputting light that results; and an extraction filter that extracts the signal light from the light output by the amplifying unit.

Optical amplifier and optical amplifying apparatus

There is provides a wavelength conversion apparatus for converting a wavelength of input signal light and for outputting output signal light of the converted wavelength. The apparatus includes a first and a second nonlinear mediums. The first nonlinear medium receives a first input light and outputs a first output light having a wavelength which is longer than that of the first input light, the wavelength being dependent on optical power of the first input light. The second nonlinear medium receives a second input light and a light output by a light source and outputs a second output light having a wavelength dependent on the wavelengths of the second input light and the light. The first output light is input as the second input light to the second nonlinear medium or the second output light is input as the first input light to the first nonlinear medium.

Wavelength conversion apparatus, wavelength conversion method, and optical add/drop multiplexer using the same

A waveform shaping apparatus includes a quantum dot optical amplifier in which an amplification factor of input signal beams saturates if the optical power of the signal beams is equal to or greater than a predetermined value; and a quantum dot saturable absorber in which an absorption factor of the input signal beams saturates if the optical power of the signal beams is under a predetermined value. The quantum dot optical amplifier and the quantum dot saturable absorber are connected in series with a transmission path of the signal beams, and shape the waveform of the signal beams. Voltages applied to the quantum dot optical amplifier and the quantum dot saturable absorber, respectively, are adjusted based on the optical power of the signal beams.

Waveform shaping apparatus, optical transmission system, and waveform shaping method

An O/E conversion element converts an input NRZ optical signal into an electric signal. A clock recovery circuit recovers a clock signal from the electric signal obtained by the O/E conversion element. A phase modulator applies phase modulation to the NRZ optical signal, using the recovered clock signal. An intensity modulator applies intensity modulation to the NRZ optical signal, using the recovered clock signal. A dispersion medium compensates for a frequency chirp of an optical signal output from the intensity modulator.

Optical signal processing apparatus

In a method and an optical switch by which a signal light is accurately switched even if a polarization state of a signal light inputted has a fluctuation, power of an output light of a polarizer which receives a signal light extracted from an output light of a nonlinear optical medium is monitored and a polarization state of an input signal light to the nonlinear optical medium is controlled so that the power becomes minimum (or maximum). The polarization state of the input signal light is monitored, a calculation of performing a predetermined conversion is executed to the polarization state of the input signal light, and a calculated polarization state is recorded (or recorded without conversion). A polarization state of a control light with respect to the input signal light is monitored and the polarization state of the control light is controlled so as to coincide with the polarization state of the input signal light recorded.

Optical switching method and optical switch

According to an aspect of embodiment, an optical switch comprises a signal light input unit, a control light input unit, a first polarization controller, a second polarization controller, a coupler, a nonlinear medium, a monitor and a controller. The first polarization controller controls a polarization of a signal light. The second polarization controller controls a polarization of a control light. The nonlinear medium generates an intensity correlation signal. The monitor monitors a polarization state of light outputted from the nonlinear medium. The controller controls the first polarization controller and the second polarization controller on the basis of the polarization of the signal light and the polarization of the control light.

Optical switch and optical switch control method

In an optical waveform measurement system, a phase comparator compares phases between an electric signal output from a PD and an electric signal output from a mixer, and outputs a signal having an amplitude proportional to the phase difference of the two electric signals to a VCO via an LPF, as an error signal. A BPF removes a jitter from the electric signal output from the VCO, and a sampling pulse light source outputs sampling light based on the electric signal with the jitter removed. An optical sampling gate samples signal light to be measured with sampling light output from a sampling pulse light source, and the sampled signal light to be measured is measured by an oscilloscope.

Optical waveform measurement system and optical waveform measurement method

According to an aspect of an embodiment, an optical switch comprises:

Optical switch and optical waveform monitoring apparatus

The present invention relates an optical waveform measuring apparatus designed to eliminate the polarization dependency of an intensity correlation signal without a polarization diversity arrangement. The apparatus comprises a sampling light outputting unit for outputting a sampling light pulse to sample light under measurement, a sampling result outputting unit for developing a nonlinear optical effect stemming from the light under measurement and the sampling light pulse from the sampling light outputting unit to output light corresponding to a result of the sampling of the light under measurement, and a polarization state control unit for, before the start of the measurement of the light under measurement, carrying out control on the basis of a power level of the light from the sampling result outputting unit so that a polarization state of the light under measurement, which is to be inputted to the sampling light output unit, is placed into a predetermined state.

Optical waveform measuring apparatus and optical waveform measuring method

An optical processing device includes: a light source that outputs second light having a first polarization state or a second polarization state in synchronization with the pulse timing of the pulse of first light; a first nonlinear medium that controls the polarization state of the first light pulse in accordance with the polarization state of the second light pulse, using a nonlinear effect; and a separator that outputs the first light pulse from the first nonlinear medium selectively to a first output path or a second output path in accordance with the polarization state controlled by the first nonlinear medium. In this device, the first nonlinear medium uses the nonlinear effect to compensate the level of each first light pulse output selectively to the first output path or the second output path by the separator, with each first light pulse receiving the energy of the second light pulse.

Optical processing device and optical processing method

A method of providing a multi-wavelength light source includes the steps of modulating an optical pulse source so as to output optical pulses with a designated repetition frequency, time-division multiplexing the optical pulses output by the optical pulse source so as to output optical pulses with a repetition frequency which is an integral multiple of the designated repetition frequency, and demultiplexing wavelengths of the optical pulses with the repetition frequency which is the integral multiple of the designated repetition frequency so as to output the wavelengths as the multi-wavelength light source.

Method of and apparatus for providing multi-wavelength light source

A clock extracting apparatus arranges bit intervals of a signal light train incident on a signal light processing section to have uneven periods, makes bit intervals between a predetermined signal light and signal lights adjacent to the predetermined signal light to be longer than a switching time of an electro-optical gate, selectively demultiplexes the predetermined signal light using the electro-optical gate, and extracts a clock synchronized with the signal light train from the demultiplexed signal light. Thus, it becomes possible to extract a clock synchronized with an ultra-high speed from a signal light train.

Clock extracting method and apparatus thereof

A first polarization controller controls a polarization state of measured light. A second polarization controller controls a polarization state of an optical sampling pulse. The measured light and the optical sampling pulse having the polarization states controlled are input to an optical fiber. An optical signal output from the optical fiber is transmitted to a polarizer. A first control unit adjusts the first polarization controller based on the measured light output from the optical fiber and the measured light output from the polarizer. A second control unit adjusts the second polarization controller based on an optical sampling pulse output from the optical fiber. Waveform measurement is performed by using the output of the polarizer.

Optical waveform measurement apparatus and optical waveform measurement method

An optical phase modulator made of lithium niobate or the like phase-modulates the output light of a single-wavelength laser light sourcethat emits CW light, and the phase-modulated light is inputted to a dispersion medium. The positive chirp and negative chirp of light to which frequency chirp is applied by phase modulation draw near in the dispersion medium and an optical pulse is generated.

Optical device for optical communication

Reflection means such as a mirror are provided on the output end of an optical fiber, and the input signal light and control light are returned to the optical fiber. Although the zero-dispersion wavelength of the optical fiber fluctuates in the longitudinal direction, if the length is relatively short, it is possible to manufacture a high yield of optical fibers, which monotonically changes the zero-dispersion wavelength. Therefore, a relatively short optical fiber with a monotonic zero-dispersion change can be used. Since the zero-dispersion change is monotonic and the optical fiber is short, the amount of change in the zero-dispersion wavelength is small and the bandwidth becomes broader when the control light is set at the position of the average zero-dispersion wavelength. Additionally, although the length of the optical fiber is short, the operating length is twice as long and thus the generation efficiency does not degrade.

Growing community of inventors

Kawasaki, Japan

Fumio Futami