CN1113490C - Optical module for light-time domain reflectometer with wide dynamic range - Google Patents
Optical module for light-time domain reflectometer with wide dynamic range Download PDFInfo
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- CN1113490C CN1113490C CN00107854A CN00107854A CN1113490C CN 1113490 C CN1113490 C CN 1113490C CN 00107854 A CN00107854 A CN 00107854A CN 00107854 A CN00107854 A CN 00107854A CN 1113490 C CN1113490 C CN 1113490C
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Abstract
The present invention relates to an optical module of an optical time domain reflectometer used for high dynamic ranges. The optical module comprises a pulsed laser emitter and a light receiving converter, wherein the pulsed laser emitter comprises an amplifier, a plurality of groups of analogue switches and pulsed laser generators. The amplifier, the analogue switches and the pulsed laser generators are connected in sequence, and the analogue switches and the pulsed laser generators can be respectively and selectively switched on. The light receiving converter comprises a photoelectric converter, a current-voltage converting circuit, a signal amplifying circuit and a high-speed A/D analog-digital converting circuit. An optical signal can be converted into a current signal by the photoelectric converter, and a current signal can be converted into a voltage signal by the current-voltage converting circuit. The optical module favorably solves the problems of weak optical signal monitoring and optical signal detection in high dynamic ranges.
Description
Technical field
The present invention relates to the optical module device in a kind of optical fiber communication, exactly, relate to a kind of optical module that is used for the optical time domain reflectometer of high dynamic range, belong to the technical field of fiber lengths transmission attenuation test.
Background technology
Along with the development of Fibre Optical Communication Technology, since the eighties, the fiberize of network is one of main trend of countries in the world network development always.The formation of the communication network of current various countries mainly is as the transmission basis with fiber optic network.And when building and safeguarding lightguide cable link, all to carry out the test of optical fiber transmission property with optical time domain reflectometer.Optical time domain reflectometer is the core technology in the on-line monitoring system of fiber optic network, and its dynamic range is big, and then the distance that can monitor and scope are big more, help the fast quick checking barrier and the block removing of lightguide cable link.
The basic functional principle of optical time domain reflectometer OTDR (Optical Time-Domain Reflectometry) be by the back-scattering light of test pulse laser on optical fiber transmission line in time the energy distribution curve analysis of (distance) obtain the transmission characteristic such as length, decay, fault of optical fiber, promptly to light pulse of tested optical fiber input, when light pulse when fibre circuit is propagated forward, scattering and reflect part signal; Optical time domain reflectometer is in optical fiber transmitted pulse signal, the part signal of monitoring this scattering and reflecting at its same end, and this signal of returning carried out the continuous high speed sampling processing, thereby obtain characteristics such as the signal transmission attenuation of fibre circuit and Fault Diagnosis location.
Because light pulse signal will be decayed in the process of transmission, scattering simultaneously and the signal that reflects also will be decayed, and like this, at the front end of optical fiber, because the close together of light pulse signal transmission, the signal that scattering is returned is stronger; And the distance of light pulse signal transmission is far away more, and its scattering and the signal that reflects are just weak more.As developing the optical time domain reflectometer of a dynamic range up to 35dB, because detected light pulse will be gone on one back and forth toward ground return at this fibre circuit, its attenuation amplitude is actual to be double, therefore the signal strength signal intensity that needs to detect is at least 70dB, adding optical fiber initiating terminal connector has a big influence such as Fresnel reflection signal, needs measured signal strengths to be generally more than the 80dB.The measured signal of great dynamic range like this, it is impossible wanting once to come out with regard to the energy acquisition process, in addition, because the maximum pulse that present high-power pulsed laser can be launched can not surpass 20 microseconds, peak power is no more than 200 milliwatts, under emission maximum luminous power condition, can calculate the optical signal power maximum that scattering is returned in the fibre circuit according to the Rayleigh scattering computing formula is about-30dBm, after deducting 70dBm again, the minimum light signal power that then will detect is about-100dBm, detect weak one like this, must use highly sensitive detector and use low noise amplifier.
Summary of the invention
The purpose of this invention is to provide a kind of optical module that can fill up the optical time domain reflectometer that is used for high dynamic range of above-mentioned technological gap, this optical module is used to detect faint optical signal and realizes the optical time domain reflectometer that high dynamic range signal detects.
The object of the present invention is achieved like this: include pulse laser reflector and light-receiving transducer two parts, described pulse laser reflector is by the amplifier that is linked in sequence, the pulse laser generator is formed, the light-receiving transducer is then by the optical-electrical converter that light signal is converted to current signal, current signal is converted to the current-to-voltage converting circuit of voltage signal, signal amplification circuit and high-speed a/d analog to digital conversion circuit are formed, and it is characterized in that: be connected with some groups of analog switches can selecting conducting respectively between the amplifier of pulse laser reflector and pulse laser generator.
Wherein the amplifier in the pulse laser reflector is provided with the potentiometer of its multiplication factor of scalable.
Wherein some groups of analog switches in the pulse laser reflector can be three groups, and these three groups of analog switches can be controlled respectively and be made each switch independence conducting work, also can controlledly respectively make it conducting in twos, perhaps three switch conducting work together.
Optical-electrical converter in the light-receiving transducer adopts highly sensitive APD detector to form.
Current-to-voltage converting circuit in the light-receiving transducer is to form with the low noise operational amplifier; be provided with in its circuit when the large-signal reverse-conducting; the high speed Schottky diode that circuit is shielded, and prevent to vibrate, the electric capacity of limiting bandwidth, minimizing noise.
Signal amplification circuit in the light-receiving transducer adopts the low noise operational amplifier to form, and its normal phase input end is provided with the biasing circuit of raising DC level.
The present invention is a kind of optical module that adopts the multiple technologies means to solve the monitoring faint optical signal preferably and realize a high dynamic range optical signal detecting difficult problem, for the development and production optical time domain reflectometer that over one hundred kilometer optical fiber of long palm fibre tested, looked into the high dynamic range of barrier of adjusting the distance provides Primary Component.
Description of drawings
Fig. 1 is the block diagram that hardware configuration of the present invention is formed.
Fig. 2 is the functional-block diagram of the pulse laser drive part among the present invention.
Fig. 3 is that hardware configuration of the present invention is formed block diagram.
Fig. 4 divides the optical fiber attenuation performance diagram of three sections measurements for wavelength 1550nm.
Fig. 5 is the spliced curve chart of wavelength 1550nm.
Fig. 6 divides the optical fiber attenuation performance diagram of three sections measurements for wavelength 1310nm.
Fig. 7 is the spliced curve chart of wavelength 1550nm.
Embodiment
Form block diagram referring to hardware configuration of the present invention shown in Figure 1.The present invention is a kind of optical module that is used for the optical time domain reflectometer of high dynamic range, and it includes pulse laser reflector 1 and light-receiving transducer 2 two parts are formed.Wherein pulse laser reflector 1 by the amplifier 11 that is linked in sequence, can select the some groups of analog switches 12 of conducting and pulse laser generator 13 to be formed respectively.Wherein the amplifier 11 in the pulse laser reflector 1 is provided with the potentiometer of its multiplication factor of scalable.Some groups of analog switches 12 in the laser pulse driver 1 can be three groups (as shown in Figure 2), these three groups of analog switches can be controlled respectively and be made each switch independence conducting work, also can be controlled respectively and make it conducting in twos, perhaps three switch conducting work together.Current-to-voltage converting circuit 22, signal amplification circuit 23 and high-speed a/d analog to digital conversion circuit 24 that light-receiving transducer 2 then is converted to voltage signal by the optical-electrical converter 21 that light signal is converted to current signal, with current signal are formed.Optical-electrical converter 21 in the light-receiving transducer 2 adopts highly sensitive APD detector to form.Current-to-voltage converting circuit 22 in the light-receiving transducer 2 is to form with the low noise operational amplifier; be provided with in its circuit when the large-signal reverse-conducting; the high speed Schottky diode that circuit is shielded, and prevent to vibrate, the electric capacity of limiting bandwidth, minimizing noise.Signal amplification circuit 23 in the light-receiving transducer 2 adopts the low noise operational amplifier to form, and its normal phase input end is provided with the biasing circuit of raising DC level.The 10th, coupler.
Fig. 1 has also showed operation principle of the present invention, after external Digital Circuit Control optical module of the present invention is by pulse laser reflector 1 and laser pulse of coupler 10 emissions, this laser pulse is coupled into tested optical fiber 3 by the fiber coupler 10 of a 50:50, this laser pulse is scattering and the light signal that reflects in the process of 3 li transmission of optical fiber, again by the optical-electrical converter 21 in the light-receiving transducer 2 of optical coupler 10 these modules of input (that is: APD pipe), the APD pipe then converts light signal to current signal, be input to high-speed a/d analog to digital conversion circuit 24 by current-to-voltage converting circuit 22 and signal amplification circuit 23 then, at last by the test of sampling of 24 pairs of signal waveforms of high-speed a/d analog to digital conversion circuit.For realizing the test of OTDR high dynamic range, as shown in Figure 2, the present invention is the size by control impuls generating laser 1 emitted laser energy, and optical fiber 3 realized that the method for areal surveys realizes goal of the invention, promptly when the previous paragraphs of measuring from the whole optical fiber of tester close together, because its scattering and reflect signal stronger, at this moment the switch a conducting of 12 li of some groups of analog switches in the control impuls generating laser 1 is launched the laser pulse of less energy and is tested; When the interlude of measuring from the moderate whole optical fiber of tester distance, because its scattering and the signal strength signal intensity that reflects are moderate, at this moment control switch a, the b conducting of 12 li of some groups of analog switches, launch the laser pulse of medium energy and test; And when measuring from the back of tester distance whole optical fiber far away section, just control switch a, b, all conductings of c of 12 li of some groups of analog switches, so that emission maximum laser pulse energy is tested the signal strength signal intensity that improves its scattering as much as possible and reflect.At last, above-mentioned three sections results that test respectively are stitched together, can obtain the transmission characteristic of whole optical fiber.In Fig. 2, the amplifier 11 in the pulse laser reflector 1 is provided with the potentiometer of its multiplication factor of scalable.This is because the drive current of different lasers is different, regulates this potentiometer and can satisfy the needs that various lasers drives.
Referring to shown in Figure 3, in order to detect faint optical signal, the present invention adopts high sensitivity APD detector and low noise amplifier, and adopts some to reduce the technical measures of noise and interference simultaneously.For example: the signal amplification circuit 23 in the light-receiving transducer 2 adopts the operational amplifier OPA655 of characteristics such as having low bias current (5pA), high input impedance, bandwidth is wide, noise is low to form; diode in this amplifying circuit is the high speed Schottky diode; can reverse-conducting when large-signal, circuit is shielded.Also be provided with in this circuit and prevent to vibrate, limiting bandwidth, reduce the electric capacity of noise contributions.APD bias circuit in the optical-electrical converter 21 is to provide reverse bias-voltage to the APD detector, reducing noise, and reduces its ripple as far as possible.231 of biasing circuits in the signal amplification circuit 23 are used to raise DC level, disturb so that reduce.In addition, this optical module of the present invention is when wiring, and its holding wire will be lacked and slightly, should and be disturbed bigger line to separate with big current signal line.APD device and amplifying circuit are then used shielding box and are shielded.
The present invention has developed sample, and tests enforcement, is 1550nm below with optical maser wavelength, and laser pulse width is 20 microseconds, and tested optical fiber is that 150 kilometers experimental example further describes application of the present invention and operation principle.Curve 1 shown in Figure 4 is the switch a conducting of 12 li of some groups of analog switches in the control impuls generating laser 1, launches the measurement curve of less energy laser pulse; Curve 2 is switch a, the b conducting of 12 li of some groups of analog switches in the control impuls generating laser 1, launches the measurement curve of moderate energy laser pulse; Curve 3 is switch a, b, the c conducting of 12 li of some groups of analog switches in the control impuls generating laser 1, the measurement curve of the strong energy laser pulse of emission.Measuring curve from these three groups can find out, when the less laser energy of emission, because of the fiber distance of its measurement nearer, during the beginning close together, the linearity of measuring is better, but when distance increased than far away or emitted laser energy, signal had at this moment just exceeded the range ability of amplifier and A/D conversion, the nonlinear curve phenomenon occurred.Above-mentioned three sections curves can be taken all factors into consideration and splice, just can obtain the measurement curve of high dynamic range as shown in Figure 5.
The inventor utilizes optical module of the present invention to carry out optical maser wavelength for 1310nm, laser pulse width are that 20 microseconds, tested optical fiber are 125 kilometers test enforcement again, its operation principle also can be described and how use it.As shown in Figure 6, curve 1,2,3 be respectively control emission pulsed laser energy little, in, the curve tested respectively when big, Fig. 7 is its spliced measurement curve, from measurement result, its dynamic range can reach 35dB.Can illustrate that from above-mentioned two embodiment optical module of the present invention uses aforesaid way can finish the test of great dynamic range, realizes goal of the invention.
Claims (6)
1, a kind of optical module that is used for the optical time domain reflectometer of high dynamic range, include pulse laser reflector and light-receiving transducer two parts, described pulse laser reflector is by the amplifier that is linked in sequence, the pulse laser generator is formed, the light-receiving transducer is then by the optical-electrical converter that light signal is converted to current signal, current signal is converted to the current-to-voltage converting circuit of voltage signal, signal amplification circuit and high-speed a/d analog to digital conversion circuit are formed, and it is characterized in that: be connected with some groups of analog switches can selecting conducting respectively between the amplifier of pulse laser reflector and pulse laser generator.
2, the optical module that is used for the optical time domain reflectometer of high dynamic range as claimed in claim 1 is characterized in that: wherein the amplifier in the pulse laser reflector is provided with the potentiometer of its multiplication factor of scalable.
3, the optical module that is used for the optical time domain reflectometer of high dynamic range as claimed in claim 1, it is characterized in that: wherein some groups of analog switches in the pulse laser reflector can be three groups, these three groups of analog switches can be controlled respectively and be made each switch independence conducting work, also can controlledly respectively make it conducting in twos, perhaps three switch conducting work together.
4, the optical module that is used for the optical time domain reflectometer of high dynamic range as claimed in claim 1 is characterized in that: the optical-electrical converter in the light-receiving transducer adopts highly sensitive APD detector to form.
5, the optical module that is used for the optical time domain reflectometer of high dynamic range as claimed in claim 1; it is characterized in that: the current-to-voltage converting circuit in the light-receiving transducer is to form with the low noise operational amplifier; be provided with in its circuit when the large-signal reverse-conducting; the high speed Schottky diode that circuit is shielded, and prevent to vibrate, the electric capacity of limiting bandwidth, minimizing noise.
6, the optical module that is used for the optical time domain reflectometer of high dynamic range as claimed in claim 1, it is characterized in that: the signal amplification circuit in the light-receiving transducer adopts the low noise operational amplifier to form, and its normal phase input end is provided with the biasing circuit of raising DC level.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN00107854A CN1113490C (en) | 2000-06-27 | 2000-06-27 | Optical module for light-time domain reflectometer with wide dynamic range |
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| Application Number | Priority Date | Filing Date | Title |
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| CN00107854A CN1113490C (en) | 2000-06-27 | 2000-06-27 | Optical module for light-time domain reflectometer with wide dynamic range |
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| CN1330265A CN1330265A (en) | 2002-01-09 |
| CN1113490C true CN1113490C (en) | 2003-07-02 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1300956C (en) * | 2004-04-06 | 2007-02-14 | 华为技术有限公司 | Light module of light time domain reflector, light time domain reflector and fibre-optical testing method |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101692623B (en) * | 2009-08-29 | 2012-05-30 | 桂林信通科技有限公司 | Method for utilizing test signal for delivering management information in optical fiber online protection system |
| CN102223174B (en) * | 2011-05-25 | 2014-03-19 | 青岛海信宽带多媒体技术有限公司 | Optical module integrated with function of optical time domain reflectometer |
| CN102455246B (en) * | 2011-12-12 | 2014-07-02 | 山东信通电器有限公司 | Low-noise and anti-interference optical-time-domain reflectometer with secondary shielding |
| JP6710970B2 (en) * | 2015-12-28 | 2020-06-17 | ソニー株式会社 | Transmission device and transmission method |
| CN105891844B (en) * | 2016-04-24 | 2018-02-23 | 西南技术物理研究所 | Dual-mode laser impulse ejection controls and echo signal processing system |
| CN113514817A (en) * | 2020-04-09 | 2021-10-19 | 武汉海达数云技术有限公司 | Ultra-high dynamic range laser pulse signal detection processing circuit structure |
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2000
- 2000-06-27 CN CN00107854A patent/CN1113490C/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1300956C (en) * | 2004-04-06 | 2007-02-14 | 华为技术有限公司 | Light module of light time domain reflector, light time domain reflector and fibre-optical testing method |
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