CN1273815C - Method for measuring signal optical information noise ratio in light wave length, power monitor - Google Patents

Abstract

The present invention provides a method for measuring the optical signal-to-noise ratio of a signal in a power monitor with a long optical wave the present invention is composed of three parts: 1*N light switches with a path selecting function, a color dispersion part with N input ports between every two of which a certain included angle is formed, and a data processing part. N output ports of each of the optical switches are connected with the N input ports of the color dispersion part. The optical switches orderly gates the N input ports so that an optical signal is orderly input into the N input ports of the color dispersion part. The color dispersion part is used for realizing space separation of optical signals with different wave length, which are focalized in different positions of a detecting plane. The N input ports cause a whole optical spectrum which passes through the input optical signals to orderly and horizontally move a section of distance. The data processing part is used for measuring, analyzing and processing data, an outputting the wavelength, the power and the signal-to-noise ratio data of a channel.

Description

Measure the method for flashlight signal to noise ratio (S/N ratio) in the wavelength-division multiplex system in optical wavelength, the power monitor

Technical field

The present invention relates in a kind of optical wavelength, the power monitor to measure the method for flashlight signal to noise ratio (S/N ratio) in the wavelength-division multiplex system, particularly based on the method for measuring-signal Optical Signal To Noise Ratio OSNR in the optical wavelength of grating and detector array, the power monitor.

Technical background

High-speed high capacity dense wavelength division multiplexing system has begun to use widely; For guaranteeing system stability, operation reliably, need to use the key property of optical property analyzer light signal in the optical transport layer real-time monitoring system in the system, comprise wavelength of optical signal, power and Optical Signal To Noise Ratio.

Two kinds of performances and price optical property analyzer all inequality is arranged at present.A kind of wavelength, power and Optical Signal To Noise Ratio that can the measuring light signal, but price is very high, is referred to as optical property watch-dog (OPM), and another price is lower, but wavelength and power that can only the measuring light channel be referred to as optical wavelength, power monitor.Since measure the desired technical difficulty height of OSNR of light signal in the wavelength-division multiplex dwdm system, complex process, and required device costliness is so the OPM of the wavelength that can measure, power and signal to noise ratio (S/N ratio) is also very expensive.Though and optical wavelength, the power monitor price of measuring wavelength and power at present are lower, owing to the ability of the OSNR that does not have measuring-signal is restricted its application.

In based on the optical wavelength of grating and detector array, power monitor, use the detector array of low passage, as 8,16,32,40 passages etc.And high performance optical property watch-dog (OPM), perhaps use the detector array of 256 or 512 expensive passages, perhaps use extremely expensive high-performance to coordinate wave filter, the technology of supporting peripherals is also required very high, this makes that all the cost of high performance optical property watch-dog is high and manufacture difficulty is big.

Summary of the invention

The objective of the invention is for satisfying high-performance, the demand of optical property watch-dog cheaply, solve existing problem, make the optical property watch-dog both have very high test performance, simultaneously have very low cost again and the method for Optical Signal To Noise Ratio in the wavelength-division multiplex system is provided in a kind of optical wavelength that provides, power monitor.In based on the optical wavelength of grating and detector array, power monitor, make in this way, can obtain the ability of the measuring light signal OSNR that high performance watch-dog has with low cost.

Measure the method for Optical Signal To Noise Ratio in the wavelength-division multiplex system in optical wavelength of the present invention, the power monitor, comprise measurement and processing to light signal, be to be distributed on the array detection plane by the spectral space of chromatic dispersion beam splitter group partly with light signal by the light signal that the light input end mouth is imported, with the spectrum of light signal space distribution translation one segment distance successively on detection plane, make same passage can distinguish measured signal power and noise power, signal power and the noise power data measured are analyzed and handled by data processing section; By optical design the center of the channel of each standard in the wavelength-division multiplex dwdm system is dropped in each passage; The method of described measuring-signal Optical Signal To Noise Ratio, the output spectrum of the light of different incidence angles the size of spatial translation distance by system in the minimum interval decision of channel.

Measure the method for Optical Signal To Noise Ratio in the wavelength-division multiplex system in described optical wavelength, the power monitor, in data processing, can use and eliminate the signal deconvolution algorithm of crosstalking, thus the power of test of raising Optical Signal To Noise Ratio (OSNR).

The invention has the advantages that with very low cost input makes the watch-dog of low performance have the function that the high-performance monitoring device is had, greatly reduce the technology and the technology difficulty of making the desired core devices of high-performance monitoring device on the one hand, also greatly reduce the cost of high-performance monitoring device on the other hand.

Description of drawings

Fig. 1 adopts to have the schematic diagram that the photoswitch of function is selected on the road: 10 photoswitches, 21,20 liang of input waveguides that angle is fixing, 30 collimation lenses, 40 diffraction grating, 50 plus lens, 60 detection plane, 70 detector arrays, 80 data handling systems.

Fig. 2 is the energy profile of wavelength-division multiplex signals at detector surface; Wavelength-division multiplex signals was at the energy profile of detector surface when 21 indications were signals from input waveguide 21 inputs, 20 indications be signal during from input waveguide 20 inputs wavelength-division multiplex signals at the energy profile of detector surface.

Fig. 3 is the fundamental diagram of grating.

Fig. 4 is the deconvolution algorithm process flow diagram.

Embodiment

For realizing purpose of the present invention, we provide and have realized this purpose method and implement device thereof.It comprises: the photoswitch of a 1 * N, and its N output terminal links to each other with N input port of chromatic dispersion part; Chromatic dispersion part with N input port, the adjacent input port of chromatic dispersion part has certain included angle, the incident angle that different input ports is corresponding different, different incident angles makes output spectrum in spatial translation; After the beam splitter group by chromatic dispersion part, the spectrum of the space distribution of light signal translation one segment distance successively on detection plane.By photoswitch gating N input port successively, from different input port input optical signals, like this, light signal can be distinguished the signal power and the noise power of light signal in the measuring system under different input configurations.A data processing section, according to formula OSNR=10*Log (signal power/noise power) to measurement data analysis, processing, thereby obtain the OSNR of light signal.

Grating principle: see Fig. 3: 1,2 is the different light beams of two bundle incident directions, and N is the grating normal.By grating equation: d (sina+sinb)=m λ as can be known, when the light of all wavelengths during all along same direction incident, the light of different wave length is along different direction outgoing; For a certain wavelength X, when diffraction progression m was identical, along the light beam of different directions incident, its diffraction direction was also different.So when polychromatic light during along different directions incident, its spectrum can whole translation.

For ease of better the understanding of the present invention, we are that example is told about principle of the present invention with optical wavelength, the power monitor of 1 * 2 photoswitch and 40 passages.

As shown in Figure 1, light signal is by the selection of photoswitch (OS) 10, and flashlight enters by in 30 to the 60 beam splitter groups of forming by input waveguide 21 earlier, and the beam splitter group makes the diverse location place of the signal focus of each passage in detection plane 60.Be the detector array of 40 passages on the detection plane, between each passage of detector array certain interval arranged.70 is several passages of detector array among the figure, and 1,2,3,4 indicate the interval between each passage respectively.Detector is placed on the detection plane, regulates position of detector, make that the channel of each standard drops on each probe access in the dwdm system, at this moment, detector measurement be the signal power of channel.The switches light switch, make light enter dispersion system by input waveguide 20, because input waveguide 20 and 21 has angle, whole spectrum translation one segment distance on detection plane from 20 light signals of importing, make light signal drop on the zone between two adjacent probe access, detector measurement is the noise power of channel at this moment, after 80s through data handling system, obtains the Optical Signal To Noise Ratio of each channel.The feeding of illustrating among Fig. 1 has gone out the situation of a channel.

Fig. 2 has provided a plurality of light signals in the wavelength-division multiplex system through behind the dispersion system, the optical power distribution synoptic diagram on detection plane and detector.Solid line is by 21 whens input, and light intensity is in the distribution situation of detector surface, this moment each channel measurement be signal power.Dotted line is by 20 whens input, and light intensity is in the distribution situation of detector surface, this moment each channel measurement be the noise power of channel.Whole spectrum is determined by the angle of input waveguide 21 and 20 in the size of the translational movement of detector surface.After measuring the signal power and noise power of each channel in the system respectively, carry out the Optical Signal To Noise Ratio that analyzing and processing just can obtain each channel in the system by data processing section.

By above explanation as can be seen, by photoswitch with have the input waveguide device of certain angle, in based on the optical wavelength of grating and detector array, power monitor, realized to channel in the measurement of signal to noise ratio (S/N ratio) of light signal.

Since the influence of factors such as the dispersive power of optical dispersion element and resolution capability, light signal meeting broadening, and in the process of test noise, the accuracy of noise testing is subjected to the influence that light signal is crosstalked, thereby influences the power of test of Optical Signal To Noise Ratio.Use optical wavelength of the present invention, power monitor to have very high Optical Signal To Noise Ratio power of test, can satisfy general application requirements.Some to the strict application of test light signal to noise ratio (S/N ratio) in, thereby we can eliminate in the measuring process crosstalking of light signal with the deconvolution algorithm of restoring signal and further improve the power of test of Optical Signal To Noise Ratio.

Fig. 4 is the deconvolution algorithm process flow diagram, and the deconvolution algorithm of restoring signal is described below:

For a linearity or approximately linear test macro, the signal that test macro records can be regarded the convolution of original signal and test macro function as, be that the signal that test macro records has not been original signal, but added the signal after test macro and the original signal interaction.Be formulated as:

G (x)=h (x) * f (x) (* number expression convolution)

Wherein g (x) is the signal that test macro records, and h (x) is a system function, f (x) to test original signal.If known system function h (x), then can derive the original signal f (x) of getting that will measure by the actual signal g (x) that records.

In the reality, by the known standard signal of input system one, the signal that the system that can obtain records is tried to achieve system function and is left in the data processor by these two signals.When other signals of system testing, recover original signal with system function of trying to achieve and the signal that records again.

Core spirit of the present invention is the input media of being made up of photoswitch and input waveguide by, thereby makes same passage can distinguish the signal to noise ratio (S/N ratio) of the power and the noise power measuring-signal of measuring-signal.Similarly, can realize the measurement of light signal signal to noise ratio (S/N ratio) equally by rotating shutter (40 among Fig. 1) or mobile detector array (70 among Fig. 1).The grating that uses among the present invention can be a transmission-type grating, also can be reflective gratings.The use-pattern of grating can be single-pass (diffraction), also can be by adding bilateral (twice diffraction) mode that catoptron is formed.

Claims (1)

1. measure the method for flashlight signal to noise ratio (S/N ratio) in the wavelength-division multiplex system in an optical wavelength, the power monitor, comprise measurement and processing to light signal, it is characterized in that being distributed on the array detection plane by the spectral space of chromatic dispersion beam splitter group partly with light signal by the light signal of light input end mouth input, with the spectrum of light signal space distribution translation one segment distance successively on detection plane, make same passage can distinguish measured signal power and noise power, signal power and the noise power data measured are analyzed and handled by data processing section; The center of the channel of each standard in the wavelength-division multiplex dwdm system is dropped in each passage; Regulate position of detector, make that the channel of each standard drops on each detector in the wavelength-division multiplex system; The output spectrum of the light of different incidence angles the size of spatial translation distance by system in the minimum interval decision of channel; In data processing, can use and eliminate the signal deconvolution algorithm of crosstalking.

Images