387 results about "Optical signal to noise ratio" patented technology

The invention relates to a method of activating an optical communication system comprising a plurality of optical amplifiers having an optical amplifier, between optical transmission lines in which wavelength-division multiplex optical signals are transmitted. The method comprises steps of: generating a desired slope in a desired wavelength range of a gain wavelength curve of the optical amplifier; adjusting an output of the optical amplifier to a desired output level; performing the above two steps in a plurality of optical repeater stations, the steps being carried out in sequence from the first to the last optical repeater stations; and adjusting a level in each optical signal in the wavelength-division multiplex optical signal so as to have substantially constant optical signal-to-noise ratios in the optical signals to be received. Activating the optical communication system according to this procedure allows proper execution of gain slope compensation, output control, and pre-emphasis control.

A fiber optic system includes a transmitter configured to utilize a plurality of modulation formats and a receiver communicatively coupled to the transmitter and configured to utilize a plurality of modulation formats. The transmitter and the receiver are cooperatively configured to set a modulation format of the plurality of modulation formats based upon optical signal-to-noise ratio associated therewith. A flexible bandwidth adaptation method includes monitoring at least one aspect of an optical link at a network element, responsive to the at least one aspect, computing a new modulation scheme for the optical link, and, if a solution is found for the new modulation scheme, changing to the new modulation format.

An apparatus and method for measuring optical signal to noise ratio (OSNR) in a node of an optical data network is disclosed. A peak power level and an average power level are measured for an optical input to an optical detector. The OSNR is determined by selecting an OSNR having the peak power level and the average power level associated with an optical signal traversing an optical path having attenuation and optical amplifier noise.

The present disclosure provides optimized configurations for a directionless reconfigurable optical add / drop multiplexer application. The present invention includes an add module with improved optical signal-to-noise through placing amplifiers prior to a multi-cast optical switch. The present invention includes various drop module configurations utilizing distributed gain, channel selective filters, and bi-directional configurations to reduce power consumption and complexity. Additionally, the present invention includes an integrated broadcast and select architecture.

An optical reception circuit generates optical electric field data by performing coherent reception of an optical signal transmitted via an optical fiber transmission line. An FIR filter filters the optical electric field data so that the optical signal is equalized. A quality monitor unit calculates the average value and the standard deviation value of the amplitude of the optical signal on the basis of the equalized optical electric field data, and further calculates an optical signal-to-noise ratio on the basis of the calculated values.

A method and apparatus is disclosed for measurement and monitoring of in-band optical signal to noise ratio (OSNR). A two channel optical spectrum analyzer (OSA) is advantageously applied in acquiring wavelength division multiplex (WDM) signal data after it has been split according to polarization, then deriving the in-band OSNR from acquired data due to its narrow bandwidth, selective spectral shape, and capability to analyze two components of a polarized signal simultaneously. The in-band OSNR can be measured without interrupting optical transmission traffic in the network.

An OSNR monitor device includes an optical receiver including a delay interferometer which inputs an optical signal in accordance with a given bandwidth and outputs two optical signals and causes the optical signals to interfere with each other and optical detectors which outputs currents in accordance with optical powers of the optical signals output from the interferometer, an optical power monitor configured to obtain the optical powers of the optical signals received by the optical detectors included in the optical receiver, and an OSNR calculator configured to calculate an optical signal-to-noise ratio in accordance with the optical powers obtained from the optical power monitor and the reception bandwidth.

Optical signal-to-noise ratio (OSNR) monitoring methods and apparatus are described. A tunable optical filter filters an optical channel containing an optical signal and noise. The total signal and noise power at the output of the filter is measured as the transmittance passband of the filter is varied and the maximum and minimum powers are determined. The ratio between the maximum and minimum powers is then used to determine the OSNR of the optical channel, which, for example, can be a wavelength channel in a wavelength division multiplexing (WDM) system. The ratio of the maximum signal power to the minimum signal power and the ratio of the maximum noise power to the minimum noise power are pre-determined based on the signal modulation format type and filter passband characteristics. Because the OSNR monitoring method and apparatus rely on information obtained after spectrally filtering the signal and noise, their operation is independent of any transmission effect that does not affect the optical power spectra of the signal and the noise or affects them in a known manner. For example, effects such as chromatic dispersion (CD), polarization-mode dispersion (PMD), and changes in the signal degree of polarization (DOP) and noise DOP will not affect the OSNR reading thus obtained.

An ink jet printer comprising an ink jet print head having at least one row of a plurality of ink ejecting ports for ejecting ink droplets along a plurality of ink droplet paths, the ink jet print head residing at a first elevation; a collimated light source and a detector each residing at a second elevation that is lower than the first elevation, the detector positioned opposite the collimated light source, the ink jet print head being movable to a test position where the at least one row of a plurality of ink ejecting ports can fire non-printing droplets, the collimated light source directing light at the detector along a light path that intersects the plurality of ink droplet paths when the print head resides in the test position; and an aperture located in between the collimated light source and detector and proximate to the detector to limit a field of view of the detector and increase an optical signal-to-noise ratio of the detector.

An orthogonal heterodyne in-band optical signal-to-noise-ratio (OSNR) monitoring method and apparatus that use the polarization characteristics of two narrow bandwidth filtered optical spectral components which is not only insensitive to the effects of polarization mode dispersion (PMD) and inter-channel cross-phase modulation (XPM) induced nonlinear polarization scattering, but also independent of bit rate and modulation format. The monitoring method is demonstrated for both linear and nonlinear systems.

An apparatus for monitoring a wavelength division multiplexed optical signal transmitted onto a main optical path includes: an amplified spontaneous light emitter for generating an amplified spontaneous emission signal and transmitting the same to onto a reference optical path; at least one fiber bragg grating for sending out an amplified spontaneous emission signal having a reference wavelength by reflecting or absorbing only that part of the amplified spontaneous emission signal which consists of a reflection wavelength or an absorbance wavelength; an optical switch for outputting at least one of the wavelength division multiplexed optical signals branched from the main optical path or one of the amplified spontaneous emissions including the reference wavelengths in response to a switching control signal input; a tunable optical filter for filtering the optical signal outputted from the optical switch using varied filter characteristics, and for outputting the filtered optical signal; and a control unit for measuring an optical wavelength, an optical power and an optical signal to noise ratio of the wavelength division multiplexed optical signal based on the analyzed reference wavelength.

The invention discloses an optical signal to noise ratio (OSNR) detecting method. The method comprises the steps that a wavelength label signal is loaded in an optical signal by a wavelength label loading end, the loading-modulating depth of the wavelength label signal is transmitted to an OSNR detecting end by a wavelength label channel or an optical monitoring channel; the OSNR detecting end obtains the loading-modulating depth of the wavelength label signal loaded in each wavelength optical signal; the wavelength label signal is analyzed to obtain the current modulating depth of the wavelength label signal; and the OSNR value of each wavelength optical signal is obtained according to the loading-modulating depth and the current modulating depth of the wavelength label signal. The invention simultaneously discloses an OSNR detecting system and OSNR detecting equipment. According to the invention, the scheme is suitable for OSNR test of current high-speed-ratio optical signals being 40G, 100G and the like and particularly suitable for the OSNR test of polarization multiplexing optical signals.

A method for determining an optical signal-to-noise ratio penalty as a measure for a quality of an optical signal transmitted via an optical link between a source optical node and a destination optical node in an optical network, the method includes collecting information of the optical link; determining a configuration parameter Pconf of the optical link based on the information of the optical link; adjusting the configuration parameter Pconf to an adjusted configuration parameter P′conf according to linear impairments in the optical link; and determining the optical signal-to-noise ratio penalty based on a non-linear function of the adjusted configuration parameter P′conf, the non-linear function accounting for non-linear impairments in the optical link.

The invention discloses a method for monitoring the OSNR (optical signal to noise ratio) in a high-speed DWDM (dense wavelength division multiplexing) system. The method comprises the following steps: loading a wavelength label for each wavelength optical signal outputted by a sending end, conducting broadband filtering and narrow-band filtering on the optical signal loaded with the wavelength label, measuring the total power of the optical signal by a digital signal processing technology, calculating the power of the alternating component, and calculating the OSNR according to the total power of the optical signal, the power of the alternating component and characteristic parameters of a filter. The invention further discloses a device for monitoring the OSNR in the high-speed DWDM system; and with the application of the method and the device, the defects of an existing interpolation method and an existing palarization multiplexing are overcome, and the OSNR in the high-speed wavelength division multiplexing system is monitored.

The invention provides a method and a device for optimizing dynamic transmission performance in a wavelength switched optical network. The method comprises the following steps of: making the optical signal-to-noise ratio cost of a dispersion-optimized optical path and the accumulative nonlinear phase shift have a one-to-one correspondence relationship by carrying out pre-dispersion compensation and post-dispersion compensation on source and destination nodes of an optical path; then, obtaining the optical signal-to-noise ratio cost of the optical path, using the power regulating quantity of a power-regulating point as a variable, by using the correspondence relationship, further setting a target function according to the optical signal-to-noise ratio cost and the optical signal-to-noise ratio of the optical path, and optimizing according to a predetermined optimization target and constraint conditions to obtain a node needing power regulation and the power regulating quantity of the same. According to the invention, the transmission performance of the optical path can be improved, and the blockage of physical layers, caused by the substandard physical transmission performance, is avoided.

The invention discloses a polarization interference-based in-band optical signal-to-noise ratio detection method and device. The method comprises the following steps of: dividing an input optical signal into two beams, of which one beam is used for measuring total power of the optical signal, and the other beam is used for measuring noise power in the optical signal; performing polarization beam splitting on the optical signal to obtain two branches which are perpendicular to each other in the polarization direction; adding time delay in one path of the two branches; combining the optical signals of the two branches together to obtain an optical signal with a polarization state varying along with frequency; adjusting a polarization angle of a polarizer to realize complete destructive interference of some frequency points so as to obtain an optical spectrum comprising noise power information; and calculating the optical signal-to-noise ratio according to the obtained total power of the optical signal and the noise power. According to the method and the device, the OSNR (Optical Signal to Noise Ratio) of the signal in a dynamic optical network and a high-speed optical fiber communication system can be detected, the detection range is 9-35 dB, the detection is not affected by the signal polarization state, optical fiber dispersion and polarization mode dispersion, the method and the device are transparent to a signal modulation format and a transmission rate, and the defects of the conventional OSNR detection method are overcome.

The invention discloses a modulation format identification and optical signal to noise ratio monitoring method for a coherent optical communication system, comprising: receiving signals Ex and Ey on two polarization states, performing dispersion compensation on the two signals, and using a constant modulus algorithm to perform signal pre-equalization to obtain the pre-equalized signals E'x and E'y; mapping the signals E'x and E'y to the Stokes space to obtain their statistical distributions S1d and S2d in the S1 and S2 vector directions respectively, performing first derivation on the fitted curves of the S1d and S2d to obtain feature enhancement signals S'1 and S'2 of different modulation format signals and different optical signal to noise ratio signals; training the feature enhancementsignals S'1 and S'2 based on the neural network of DNN algorithm, extracting the feature information of different modulation formats and different optical signal to noise ratio signals, and identifying the coherent optical communication quenching and tempering format and monitoring the optical signal to noise ratio signals according to the information. The invention may realize signal modulation format identification and optical signal to noise ratio monitoring simultaneously by using a single digital signal processing module without changing the configuration of the coherent receiver.

In a WDM optical communication system, at least one optical tunable filter is placed along an optical fiber provided as an optical transmission path between a transmitting station and a receiving station. The optical tunable filter has a controllable transmission factor versus wavelength characteristic. In the receiving station, the transmission characteristics (for example, optical signal to noise ratios and Q factors) for optical signals of different wavelengths propagated over the optical fiber are measured. The measurements are sent to the transmitting station. The transmitting station then properly controls both the amounts of pre-emphasis in the transmitting station and the wavelength characteristic of the optical filter on the basis of the measurements to thereby equalize the transmission characteristics for the optical signals. In this case, it is also possible to calculate the optimum proportion of allocation of control between the pre-emphasis control and the filter control and then perform the pre-emphasis control and the filter control according to the optimum proportion of allocation. In this control, the main controller may be either the transmitting station or the receiving station.

The invention provides an OSNR (Optical Signal to Noise Ratio) monitoring device for a wavelength division multiplexing system and an OSNR monitoring method. The device comprises a wavelength label analysis unit, an optical performance monitoring unit and an OSNR computing unit, wherein the wavelength label analysis unit is used for receiving a monitoring optical signal provided by the wavelength division multiplexing system, obtaining the signal power of a channel in which each wavelength signal in the monitoring optical signal is positioned and transmitting the signal power to the OSNR computing unit; the optical performance monitoring unit is used for receiving the monitoring optical signal provided by the wavelength division multiplexing system, obtaining the total power of the channel in which each wavelength signal in the monitoring optical signal is positioned and transmitting the total power to the OSNR computing unit; and the OSNR computing unit is used for obtaining the OSNR of the wavelength division multiplexing system according to the signal power and the total power of each channel transmitted by the wavelength label analysis unit and the optical performance monitoring unit. With the adoption of the technical scheme, the OSNR monitoring of the wavelength division multiplexing system can be realized.

The invention discloses a method of calculating optical signal noise ratio in a DWDM system, which is suitable for the DWDM system comprising an optical amplifier. The invention comprises: step 1, in accordance with the optical amplifier noise coefficient and the gain, a spontaneous radiation noise power is amplified; Step 2, the single-channel input power of the optical amplifier is calculated, and an input optical signal noise ratio is obtained in accordance with the single-channel input power and the input optical signal noise ratio; Step 3, output noise power is obtained from the amplified spontaneous radiation noise power, the input noise power, and the gain; step 4, the single-channel output power is calculated and the signal output optical signal noise ratio is obtained in accordance with the output signal power and the output signal noise power. The invention overcomes the shortcomings that the estimation method of the optical signal noise ratio is unable to adapt the non-equidistant system, span transmission optical power uneven system, lower signal noise ratio system and horizontal compatible system in the prior art.

The invention relates to an optical parametric amplifier-based all-optical signal quality monitor, which is used for the online monitoring of optical signal chromatic dispersion, an optical signal to noise ratio and polarization mode dispersion. The monitor comprises a pre-optical amplifier, a semiconductor laser, a coupler, an optical parametric amplifier, an output optical filter and an optical power meter. The semiconductor laser sends out low-power continuous detection light; the continuous detection light and signal light amplified by the pre-optical amplifier are subjected to beam combination by the couple and then injected into the optical parametric amplifier; the optical parametric amplifier transfers the energy of the signal light to the detection light and idle light based on a one-order four-wave mixing effect; and the detection light and the idle light output by the optical parametric amplifier are metered by the optical power meter after passing through the output optical filter. The monitor has the advantages of high response speed, high flexibility, wide working wave band and can respond to the signal rate and modulation format at any time through monitoring; and the monitor is applicable for the online monitoring of quality parameters of signals with the single channel speed of over 100 Gb / s.

The invention relates to the field of optical communication, in particular to an optical signal to noise ratio detection method and an optical signal to noise ratio detection device. The device comprises a polarization state switching module, a polarization beam splitter, a first photoelectric conversion module, a second photoelectric conversion module, a power comparison module and an optical signal to noise ratio (OSNR) computing module, wherein the polarization state switching module performs preset switching on the polarization state of to-be-detected light input into the polarization state switching module according to an indication signal generated by the power comparison module, so that an average power difference between two optical signals output by the polarization beam splitter meets preset requirements; and when the average power difference between the two optical signals meets the preset requirements, the OSNR computing module performs signal equalization on electric signals obtained by the photoelectric conversion of the two optical signals, and computes the OSNR of the to-be-detected light based on the equalized signals. By the OSNR detection scheme provided by the embodiment of the invention, a polarization controller is not required, and the OSNR of the to-be-detected light can be detected rapidly and highly efficiently with low cost.

An apparatus and method for measuring optical signal-to-noise ratio in optical communications includes (1) a variable optical band-pass filter (VOBPF) that passes the amplified output beam when the beam wavelength is the same as the passing wavelength of the VOBPF; (2) a 1x4 beam distributor for distributing the passing beam of the VOBPF into four streams; (3) a measuring device for measuring Stokes parameters S0, S1, S2, S3 from the four distributed beams; (4) a calculating device for calculating the optical signal power by finding the power of the polarized component of the amplified output beam from the Stokes parameters S1, S2, and S3; (5) a calculating device for calculating the noise power by finding the power of the noise included in the amplified output beam from Stokes parameter S0 and the optical signal power; and (6) a dividing device for calculating the ratioat the passing wavelength.

A method and apparatus for improving the accuracy of in-band OSNR measurements using a conventional polarization extinction or polarization-nulling method. In particular, the severe degradations of the polarization extinction that result from slow and fast polarization fluctuations in the optical signal components during the in-band OSNR measurement are substantially mitigated by rapidly and / or randomly changing the state of polarization prior to conventional polarization control and filtering.

The invention discloses a method and a device for producing a plurality of paths of coherent light carriers, which relate to the field of optical communication. The method comprises the following steps of: transmitting laser light, output by a continuous wave laser, with a stable given wavelength into an optical frequency comb to produce a plurality of frequency comb lines, and obtaining N1 frequency comb lines by using a band path optical filter, wherein N1 is a positive integer more than 1; and dividing the N1 frequency comb lines into n paths of signals, performing frequency shifting on the second to nth paths of signals respectively, and commonly forming the required plurality of paths of coherent light carriers by using the first path of signals and the second to nth paths of frequency-shifted signals, wherein n is the positive integer more than 1. By the method and the device, the requirements of the optical frequency comb (OFC) on devices such as a radio frequency amplifier, a modulator and the like can be reduced, a required number of light carriers can be produced, relatively higher flatness and a higher optical signal to noise ratio (OSNR) are ensured, and the practicability of an orthogonal frequency division multiplexing (OFDM) system is further improved.

The present inventionrelates to a testing method of a WDM system light signal-to-noise. First, choose a spectroanalysis instrument to measure the spectrum, and then find the left edge point Lambada L 1 and the right edge point Lambada R 1 of the signal bandwidth as well as the left edge point Lambada L 2 and the right edge point Lambada R 2 of the chromatic dispersion bandwidth, counte the power medium value Pn Lemean and the Pn Rmean respectively in the left interval[Lambada L 2 Lambada L 1] and the right interval[Lambada R 1 Lambada R 2], and worke out the yawp power Pres in the resolving capability BRES which is on the position of the signal wavelength, choose the yawp power P yawp power in the yawp bandwidth Bzs as well as the yawp power in the signal bandwidth and the yawp power P in the signal bandwidth B; second, count the total power in the signal bandwidth by the power spectral density Pd integral; and finally, count the signal-to-noise based on the signal power and the yawp power.

The invention discloses a monitoring method for the optical signal to noise ratio. Two kinds of filtering information are adopted for carrying out filtering and interferometry on optical signals and ASE noise of a transmitting terminal to obtain correction values and adopted for carrying out filtering and delayed interferometry on monitored channels on optical channel monitoring points to obtain corresponding correction values in a combined mode, then the absolute power value of the optical signals and the absolute power value of the ASE noise are obtained, and therefore the optical signal to noise ratio is monitored. Based on the same inventive concept, the invention further provides a monitoring device for the optical signal to noise ratio. The monitoring device is good in resistance to spectrum distortion damage of monitored signals, and can monitor the optical signal to noise ratio of the monitored signals accurately on line.

A WDM optical network comprising a plurality of nodes has a first apparatus for optical analysis at the site of a first optical amplifier upstream of the first node, a second apparatus for optical analysis at the site of a second optical amplifier at the downstream output of the first node, and a third apparatus for optical analysis at the site of a third optical amplifier further downstream of the first node, where knowledge of the optical sin to noise ratio (OSNR) is desired. The first, second and third apparatus are for measuring the signal level at frequencies both at and in-between the channel frequencies. The signal levels at the channel frequencies and between the channel frequencies at the first, second and third apparatus are used to derive the OSNR at the third apparatus. This enables the OSNR to be measured accurately at any site in the network, using calculations in which noise shaping of the nodes can be factored in to the calculation of OSNR.

An apparatus and a method for monitoring optical signal-to-noise ratio are provided. It can be applied in dense wavelength-division multiplexed networks to monitor the transmission quality of each optical channel. The apparatus comprises an optical circulator, a tunable optical filter, a dithering signal, a dithered reflector, and two photodiodes. It can be integrated on a single chip. The invention utilizes the dithering and reflection functions of the dithered reflector, and passes the signal and the noise through the tunable optical filter once and twice, respectively. When the tunable optical filter is scanning and filtering the whole spectrum, the signal and noise powers are measured by the two photodiodes, respectively. The OSNR for each optical channel is then calculated according to the signal and noise powers. It can monitor channel location, wavelength drift, and OSNR by including a wavelength locker to act as an optical channel analyzer.

An apparatus and method for monitoring an optical signal are provided. In the apparatus, a polarization adjusting unit converts the state of polarization of an optical signal. A polarization beam splitter splits the optical signal into a first polarization component and a second polarization component perpendicular to each other. An optical intensity measuring unit measures the optical intensity of the first polarization component. A feedback control unit controls the polarization adjusting unit so that the first and second polarization components are aligned to the two axes of the polarization beam splitter. A scrambler scrambles the optical signal input to the transmission optical fiber. According to the apparatus and method, optical signal-to-noise ratio (OSNR) can be measured accurately.