Fujitsu Corporation

Fujitsu Telecom Networks Limited

Satoru Okano

Kazuo Yamane

Yumiko Kawasaki

Takashi Tsuda

Akira Miyauchi

Motoyoshi Sekiya

Jeng-Yuan Yang

Yasushi Sugaya

Hiroki Ooi

Youichi Akasaka

Takuji Maeda

Takehiro Fujita

Hiroshi Nishimoto

Kentaro Nakamura

Miki Onaka

Shoichiro Oda

Yasuhiko Aoki

Hiroaki Tomofuji

Ichiro Nakajima

Ryosuke Goto

Yoshito Kachita

Takahumi Terahara

Takehito Okeno

Toru Katagiri

Masahiro Yuki

Masatake Miyabe

Taizo Maeda

Koji Bato

Hiroki Oi

Yoichi Akasaka

Tatsuhiko Saito

Yusaku Yamamoto

Makoto Yamashita

An optical transmission characteristic measurement method includes starting transmission of an optical signal from a transmitting node to a receiving node; receiving a bit error rate value measured by the receiving node and relates to the optical signal; determining whether the bit error rate value is higher than a given threshold; adjusting input power of the optical signal to lower until it is determined that the bit error rate value is higher than the given threshold when it is determined that the bit error rate value is not higher than the given threshold; estimating an optical signal to noise ratio from the bit error rate value when it is determined that the bit error rate value is higher than the given threshold; and calculating an optical signal to noise ratio based on the estimated optical signal to noise ratio and an amount of lowering of the input power.

Optical transmission characteristic measurement device and method

An optical signal-to-noise ratio monitor includes: a measuring unit that measures an optical signal-to-noise ratio of a polarization multiplexed optical signal, a polarization state of the polarization multiplexed optical signal changing with respect to time; a selector that selects, from a plurality of optical signal-to-noise ratios measured by the measuring unit at a plurality of measurement points within a designated measurement period, an optical signal-to-noise ratio that is higher than an average of the plurality of optical signal-to-noise ratios; and an output unit that outputs the optical signal-to-noise ratio selected by the selector.

Optical signal-to-noise ratio monitor and method for measuring optical signal to-noise ratio

An optical transmission device includes a reception unit that receives a first signal light and a second signal light, the first and second lights having power levels that respectively correspond to transmission distances and being transmitted; an amplification unit that amplifies the first signal light and the second signal light in accordance with a signal light having a high power level from among the received first signal light and second signal light; and a transmission unit that performs transmission of the amplified first signal light and second signal light.

Optical transmission device and optical transmission system

An optical transmission system includes: a first optical transmission device configured to transmit measurement light to an optical transmission line on a first direction; and a second optical transmission device configured, when an optical transmission characteristic is measured, to loop-back the measurement light received from the first optical transmission device through an optical transmission line on the first direction and to transmit the measurement light to the first optical transmission device through an optical transmission line on a second direction, wherein, when the optical transmission characteristic is measured, the first optical transmission device receives the measurement light loop-backed by the second optical transmission device and measures the optical transmission characteristic between the first optical transmission device and the second optical transmission device.

Optical transmission system and optical transmission device

An optical transmission apparatus including: an attenuator that attenuates a power of a first optical signal generated in a first modulation method to a first target level and attenuates a power of a second optical signal generated in a second modulation method, a modulation level in the second modulation method being lower than the modulation level in the first modulation method, to a second target level, the second target level being lower than the first target level; and a transmitter that sends a WDM signal including the first optical signal and the second optical signal that have been attenuated by the attenuator.

Optical transmission apparatus and optical transmission system

Methods and systems for in-band OSNR monitoring include a tunable optical filter to scan a passband of a desired optical channel. The optical power over the passband is measured and digitized to power waveform data. The power waveform data is processed with a digital signal processor to calculate OSNR. Additionally, various implementations accommodate dual polarization modulation formats using a parallel architecture and an alternating sequential architecture.

In-band optical signal-to-noise ratio monitor

Methods and systems for mitigating spectral offset may use a scanning optical filter to scan different frequencies (or wavelengths) in a signal bandwidth of an optical channel. The maximum optical power value for the optical channel may be accurate determined as well as an effective wavelength corresponding to the maximum optical power value.

Mitigation of spectral offset in an optical filter

An optical amplification apparatus that amplifies input wavelength-division multiplexed light includes a pump light source that outputs pump light, and an optical amplifier that amplifies the wavelength-division multiplexed light in response to a power level of the pump light. The number of wavelengths multiplexed in the wavelength-division multiplexed light is equal to or less than the maximum available number of wavelengths input to the optical amplification apparatus. The power level of the pump light is determined based on the maximum available number of wavelengths.

Optical amplification apparatus, optical transmission apparatus, and optical transmission system

The present disclosure includes a computer-implemented method of correcting a measured optical signal-to-noise ratio (OSNR) comprising receiving an optical signal and measuring OSNR of the optical signal using an interferometric OSNR monitor device. The method also includes applying a correction table to the measured OSNR to generate a corrected OSNR using a controller, the correction table comprising a correction function to counteract an artifact in the measured OSNR. The method also includes storing the corrected OSNR in a non-transitory computer-readable medium. The present disclosure also includes associated devices applying the correction table and methods of generating the correction table.

Correction table for interferometric optical signal-to-noise ratio monitor

The present disclosure includes a method of determining optical signal-to-noise ratio (OSNR) of a signal, comprising separating one polarization component from a plurality of polarization components in an optical signal, selecting one wavelength from a plurality of wavelengths in the optical signal, delaying a first portion of the one polarization component of the one wavelength of the optical signal, shifting a phase of the first portion by a first amount and the first amount plus pi radians, causing the first portion to interfere with a second portion, measuring a power of the interference of the first and second portions, receiving the power of the interference, and comparing the power of the interference when the phase is shifted by the first amount with the interference when the phase is shifted by the first amount plus pi radians to determine OSNR. The present disclosure also includes associated devices.

Dual-polarization interferometric optical signal-to-noise ratio monitor

An optical packet switching system includes an optical packet transmitter, an optical packet switching apparatus, an optical amplifier, an optical packet receiver, an information gathering unit, and a peak power calculation unit. The information gathering unit collects the packet density, time-averaged power and extinction ratio from the optical packet transmitter, collects the packet density, time-averaged power and noise figure from the optical amplifier, collects the packet density, time-averaged power, switch on/off time ratio and extinction ratio from the optical packet switching apparatus, and collects the packet density and time-averaged power from the optical packet receiver. The peak power calculation unit calculates the peak power of an optical packet signal outputted from each apparatus/device based on the collected information. The device control unit control each apparatus/device based on the calculated peak power such that the optical packet signal having a peak power according to a predetermined optical level diagram is outputted.

Optical packet switching system and method for controlling the peak power

A WDM optical transmission system includes a plurality of optical nodes optically coupled by a transmission line, a processor that is operative to calculate an amount of adjustment of a reception level capable of increasing an optical signal-to-noise ratio for each channel of the WDM light reaching the optical node positioned at a receiving end of the unit section based on information on amplification operation of the WDM light in at least one optical-amplification repeating node disposed on the optical transmission line in the unit section, and to adjust a power level corresponding to each channel of the WDM light transmitted on the transmission line from the optical node positioned at a transmission end of the unit section in accordance with a calculation result of the calculation.

WDM optical transmission system and control method thereof

An optical node apparatus according to the present invention amplifies a WDM signal light input to an input port, and thereafter, branches the amplified WDM signal light by an optical branching coupler to send the branched lights to first and second optical paths, and selects the light propagated through the first optical path by an optical switch to amplify the selected light by a post-amplifier, thereby outputting the amplified light from an output port, when the optical node apparatus is operated as an optical amplification repeating node. When the operational state is upgraded to an optical add/drop multiplexing node, an OADM section is connected between a set of connecting ports on the second optical path, and the adjustment of the OADM section is performed utilizing the WDM signal light branched by the optical branching coupler, and thereafter, the switching of the optical switch is performed to select the light on the second optical path side. As a result, since the switching the operational state from the optical amplification repeating node to the OADM node can be performed in a short time, it becomes possible to provide the continued communication service at the low initial installation cost.

Method of upgrading optical node, and an optical node apparatus

A wavelength division multiplexing (WDM) device, an optical leakage prevention method, and a WDM communication system are disclosed. The WDM device includes a level adjusting unit for receiving an optical signal, for adjusting the optical power level of the received optical signal, and for outputting the level-adjusted optical signal; and a controlling unit for analyzing the optical power level of the optical signal output from the level adjusting unit, for controlling the level adjusting unit so that the optical power level of the output optical signal stays at a constant level, and for transitioning to an 'off-state' when the optical power level of the output optical signal becomes less than a predetermined disconnection-detection threshold so that the level adjusting unit gives a predetermined attenuation to the input optical signal. The controlling unit transitions from the 'off-state' when the optical power level of the output optical signal is greater than a predetermined recovery threshold and an upstream WDM device is not in the &#x201c;off-state&#x201d;.

Wavelength division multiplexing device, an optical leakage prevention method, and a wavelength division multiplexing communication system

Dispersion compensation values are set so as to be transmittable to any path groups in a WDM optical communication system having OADM nodes, which includes transmitting-end and receiving-end terminal nodes; a WDM optical communication transmission line including a plurality of spans each having an optical fiber, the plurality of spans joining the transmitting-end and receiving-end terminal nodes; and a plurality of add drop multiplexing (OADM) nodes disposed on the optical communication transmission line; wherein when taking as the reference a residual dispersion target value of between the transmitting-end terminal and receiving-end terminal nodes, a residual dispersion target value for a node segment between one of the terminal nodes and one of the add drop multiplexing (OADM) nodes and a residual dispersion target value for a node-to-node segment between two of the add drop multiplexing (OADM) nodes are set so as to be proportional to ratios of the span counts in the node segment and in the node-to-node segment, respectively, to the total span count between the transmitting-end and receiving-end terminal nodes.

Growing community of inventors

Yokohama, Japan

Satoru Okano