CN1618152A - Return path transmitter having a closed laser control loop that is employed in a hybrid fiber / coax transmission system - Google Patents
Return path transmitter having a closed laser control loop that is employed in a hybrid fiber / coax transmission system Download PDFInfo
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- CN1618152A CN1618152A CNA028280091A CN02828009A CN1618152A CN 1618152 A CN1618152 A CN 1618152A CN A028280091 A CNA028280091 A CN A028280091A CN 02828009 A CN02828009 A CN 02828009A CN 1618152 A CN1618152 A CN 1618152A
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- 238000005259 measurement Methods 0.000 claims description 11
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/25—Arrangements specific to fibre transmission
- H04B10/2575—Radio-over-fibre, e.g. radio frequency signal modulated onto an optical carrier
- H04B10/25751—Optical arrangements for CATV or video distribution
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/068—Stabilisation of laser output parameters
- H01S5/0683—Stabilisation of laser output parameters by monitoring the optical output parameters
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/501—Structural aspects
- H04B10/503—Laser transmitters
- H04B10/504—Laser transmitters using direct modulation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/58—Compensation for non-linear transmitter output
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/0617—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium using memorised or pre-programmed laser characteristics
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/068—Stabilisation of laser output parameters
- H01S5/06804—Stabilisation of laser output parameters by monitoring an external parameter, e.g. temperature
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/068—Stabilisation of laser output parameters
- H01S5/06808—Stabilisation of laser output parameters by monitoring the electrical laser parameters, e.g. voltage or current
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- Condensed Matter Physics & Semiconductors (AREA)
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Abstract
An optical transmitter is provided that includes a laser subassembly generating an optical signal having a plurality of operating characteristics. A controller, which drives the laser subassembly by applying at least one control parameter thereto, includes a predetermined, empirically derived database relating the plurality of operating characteristics of the laser subassembly to the control parameters. The controller adjusts at least one control parameter based at least in part on data extracted from the database so that the operating characteristic is substantially optimized.
Description
Statement of related
The application requires the priority of the title of application on December 12 calendar year 2001 for the U.S. Provisional Patent Application 60/340,796 of " the return path reflector with laser controlling closed loop that uses in the hybrid fiber/coax transmission system (Return PathTransmitter Having A Closed Laser Control Loop That Is Employed In AHybrid Fiber/Coax) ".
Technical field
Relate generally to hybrid fiber/coax transmission system of the present invention, and more specifically relate to the reflector that is used for sending uplink information in the optical node of this transmission system from user's head-end.
Background technology
At present, the transmission system of using in the wired tv industry provides the transmitted in both directions of information (for example video, multimedia and/or data) between head end and a plurality of user.Typically, head end is the information (" downlink information ") of destination by the transmission of light form with each user by one or more fiber optic links to one or more optical nodes.Each node converts the downlink information of light form to the signal of telecommunication so that typically be assigned to each user by the cable plant with hybrid fiber/coaxial (HFC) architecture.
Except receiving downlink information, it is the information of destination with the head end with speech, data or the form that is combined as of the two that each user can produce.To other user or service provider's circuit, the information (" uplink information ") that this user generates is by the segmentation of coaxial cable line facility and be sent to node, so that convert the light form in order to be transferred to head end.The return path frequency band related with uplink information (for example 5-40MHz) shared by all users by same optical node service usually.
Soft cheaply, hardware component are got used to by cable service provider.This has typically limited the technical capability of the equipment that is adopted in up or the return path.Traditionally, this causes return path that limited effect is provided in providing such as the service of pay-per-use (PPV) or video request program (VOD).Especially, the generating laser that the head-end of using in each optical node sends information has simple relatively, low-cost design.For example, the gain of well-known return laser light reflector with environment change for example temperature change fluctuate and may show because the aging decreased performance that causes.In conventional system, it is stabilisation that the typical case that the gain of return path laser or luminous power only cause temperature fluctuation changes.Even in this case, the stabilization technology that is adopted also is subject to the technology of the unique property of not considering each laser.They do not monitor actual signal drive level and laser output power so that in real time other environment change is adjusted yet.These laser stabilizing circuits are usually based on the typical performance of a large amount of measured laser devices.
Consumer's the requirement of passing through cable TV service support interactive application in recent years increases greatly and expects that this requirement can continue to increase.The increase of this grade of service requires correspondingly to improve the speed of cable television network and the performance of return path, and this proposes stricter requirement so that they have better parametric stability to environment change to the return path generating laser in the HFC transmission system.
Summary of the invention
According to the present invention, a kind of optical transmitting set is provided, it comprises that a generation has the laser assembly of the light signal of a plurality of operating characteristics.One by using the controller that at least one Control Parameter drives this laser assembly, and it comprises the database that a plurality of operating characteristics and a Control Parameter laser assembly predetermined, that derive by experiment associate.This controller is adjusted at least one Control Parameter according to the data of extracting from this database at least in part, thus Optimizing operation characteristic basically.
According to one aspect of the present invention, this database is included in the closed control circuit.Alternatively, this controller can comprise that this database is positioned at look-up table wherein.
According to another aspect of the present invention, a plurality of operating characteristics of this of laser assembly comprise optical output power.Operating characteristic can also comprise BER, NPR and distortion.
According to another aspect of the present invention, Control Parameter comprises bias level, temperature, RF drive level, slope efficiency, tracking error control and threshold voltage.
According to another aspect of the present invention, a kind of method of considering the performance difference of each laser assembly is provided, these laser assemblies are used in the optical transmitting set that produces the light signal that has a plurality of operating characteristics.This method from produce for each laser assembly under operating state a plurality of operating characteristics of laser assembly and calibration curve that a plurality of Control Parameter of its application are associated.Each laser assembly is provided with a controller so that drive this laser assembly by at least one that use in these Control Parameter.Each laser assembly is set up communication between controller and the calibration curve related with given laser assembly, thereby adjust Control Parameter so that optimize at least one operating characteristic of this given laser assembly basically according to this calibration curve.
Description of drawings
Fig. 1 illustrates conventional hybrid fiber/coax transmission system.
Fig. 2 illustrates the conventional optical node that can be included in the system shown in Fig. 1.
Fig. 3 is illustrated in the calcspar that being used for of using in the optical node sends the conventional return path generating laser of uplink information.
Fig. 4 is the calcspar that is used for the return path generating laser of the optical node that makes up according to the present invention.
Embodiment
Fig. 1 describes conventional hybrid fiber/coax transmission system 20.System 20 comprises a forwarding information, and for example video, audio frequency, multimedia and/or data (" downlink information ") are so that be transferred to each user's 14 head end 10.Head end also receives the information such as video, audio frequency, multimedia and/or data (" uplink information ") that one or more users 14 produce by set-top box or cable modem.
Particularly, the combination of optical fiber and coaxial cable is sent to downlink information user 14 and uplink information is sent to head end 10 from user's terminal 14 from head end 10.As finding out among Fig. 1, uplink optical fibers 162 transmits the uplink information of light form between head end 10 and optical node 12.Similarly, downlink optical fiber 161 transmits the downlink information of light form between head end 10 and optical node 12.Single coaxial cable 18 is transmitting the uplink information of electronic format and transmitting downlink information between optical node 12 and user 14 between a group user 14 and the optical node 12.Thereby uplink information and downlink information are placed on the different frequency bands and by a FILTER TO CONTROL in the node 12.At the head end place, opto-electronic conversion (DIE) receiver 172 becomes the uplink information of light form conversion (demodulation) signal of telecommunication for the processing of carrying out in succession.Electric light conversion (E/O) generating laser 171 smooth formats downstream information in the head end 10 are so that be transferred to optical node 12 through downlink optical fiber 161.
As shown in Figure 2, optical node 12 typically comprises an O/E forward path receiver 221, is used for through optical fiber link 161 downlink information of light form being converted to the downlink electrical signal of the family 14 that sends to the user on coaxial cable 18.Optical node 12 also comprises an E/O return path reflector 222, is used for the electric form uplink information that receives through coaxial cable 18 is converted to light form uplink information, and this light form uplink information sends to return path receiver 172 along optical fiber link 162.
Fig. 3 is the calcspar that being used for of using in the conventional optical node 12 sends the E/O return path reflector 222 of uplink information.As shown in the figure, the RF signal that receives from user 14 on coaxial cable 18 finally is used for modulated laser module 24.Can buy laser module from Distributed Feedback (DFB) or Fabry-Perot (FP), this module comprises laser cavity 28 and photodiode 26.The controlled light quantity that photodiode 26 is collected the little broken face in rear portion that points to laser cavity 28.The light that this photodiode detects is common and proportional through the front facet emitted laser device actual light power output of laser cavity 28.Add electrical bias by 30 pairs of laser modules 24 of laser bias control unit.In conventional system, E/O return path generating laser 222 also comprises thermal compensation circuitry, makes the minimum that is changed to of the luminous power that receives at the head end place during with convenient optical node temperature change.This thermal compensation circuitry is provided with by open-loop configuration, and it comprises temperature sensor (thermistor) 32, voltage level compensating circuit 38 and p-i-n (positive-intrinsic-negative) diode attenuator 40.This thermal compensation circuitry compensation is because the variation of the laser output power that the temperature fluctuation in the optical node 12 causes.
In the operation, temperature sensor 32 testing environment temperature and produce one to a series of briefly with the voltage of 38 voltage amplifiers of representing.These amplifiers 38 can increase progressively by the raising of the mode of determining with a calibration curve with temperature.This calibration curve illustrates the fluctuation of the predefined relatively for example room temperature of laser Yin Wendu and the variation that occurs on gain or optical output power.The output of temperature-compensation circuit 38 is magnitudes of voltage, and this value is inversely proportional to the deviation of the optical output power of the laser expection that is caused by temperature fluctuation.This voltage is used for controlling the impedance of p-i-n diode attenuator 40.This voltage is applied to a control circuit (it comprises the level that has a plurality of breakover points and slope control), thereby the RF drive level is adjusted to efficient by the approximation to function compensate for laser diode of Control Parameter (being temperature in this example).The impedance and the temperature-compensated voltage of p-i-n diode compensation device 40 change inversely.This correspondingly controls the RF drive level of the optical modulation index (OMI) that is used for definite laser 24.Thereby, change the OMI level of laser by the variation on the RF drive level amplitude, thereby make on its optimal level that turns back to predetermined temperature.
As the front is mentioned, the various technology of the operating characteristic of stable laser, the technology of for example above-mentioned power output with respect to the temperature stabilization laser is not considered the special characteristics of each laser.On the contrary, only comprise consideration a large amount of lasers, for example typical performance of the single production lot of laser.
According to the present invention, a kind of stable or optimization laser assembly is provided, that is, the method for the operating characteristic of the output signal of the active element of this laser, this laser comprises laser cavity, photodiode and correlation electron circuit.These operating characteristics comprise optical output power, BER, NPR and the distortion of light signal without limitation.For a given laser assembly, the present invention produces a multidimensional calibration curve that the various Control Parameter of the various operating characteristics of laser output signal and this laser assembly of driving are associated.These Control Parameter comprise bias level, temperature, RF drive level, slope efficiency, tracking error control and the threshold voltage of this laser assembly.Owing to be each specific laser assembly generation calibration curve, so it reflects the actual characteristic of this laser assembly and is the typical or average performance of a large amount of laser assemblies remarkablely.This calibration curve can make any or a plurality of the associating in any or a plurality of and the Control Parameter in the operating characteristic.
Can use this calibration curve by the controller that drives this laser assembly with various different modes.For example, can this calibration curve be presented to can look-up table or other database by this controller access in.Alternatively, can adopt the operating characteristic of this laser assembly of measurement and the closed control circuit of corresponding adjustment Control Parameter.
The present invention has realized surpassing many advantages of the conventional stabilization technique of describing in conjunction with the return path generating laser shown in Fig. 3.For example, Control Parameter of using among Fig. 3 and operating characteristic only are respectively temperature and optical output power.In addition, this stabilization technique is not considered the characteristic of each laser, but only considers the typical laser diode average to a large amount of lasers (each assembly is different) characteristic.
Scheme to Fig. 3 shown in Figure 4 is carried out an improved specific embodiment of the present invention.Fig. 4 is a calcspar that is comprising according to the E/O return path generating laser 100 of closed loop laser power stabilizing circuit of the present invention, can use this return path generating laser 100 to send uplink information in the optical node as shown in Figure 4 in example.Different with the return path generating laser shown in Fig. 3, this return path generating laser adopts compensation to influence the temperature change of laser gain and the closed loop configurations of other environment change.Return path generating laser shown in similar Fig. 3, return path generating laser 100 comprises a laser module 106, for example the laser assembly that is comprising laser and photodiode that can buy from Distributed Feedback (DFB) or Febry-Perot (FP).
In the operation, the return path signal that receives from user 14 at this node place was directed into compensation electronic circuit 102 earlier before modulated laser module 106.This comprising various elements for example the compensation electronic circuit of p-i-n attenuator be used to adjust the transfer function of this electronic circuit.This compensation electronic circuit 102 responds from the amplitude level of the RF signal of its output of information adjustment of one or more feedback path reception, thereby makes the light output of this laser keep stablizing.Although Fig. 4 illustrates three such feedback paths that can adopt, the present invention includes the various schemes of any combination of adopting one or more this feedback loop.
A measurement in the feedback path shown in Fig. 4 is from the electric current that is placed in the photodiode in the laser module 106.Such as noted, the output of this photodiode and the real output of laser are directly proportional, the electric current that this photodiode produces is received by detector 108, this detector 108 becomes voltage to this current conversion, modulus (A/D) transducer 110 and then the voltage level increment that this voltage transitions one-tenth is discerned by microprocessor 112.This microprocessor 112 compares the predetermined value of the output valve of this photodiode and memory stores.The output of microprocessor is a proportional value of deviation with relative this predetermined value of actual output of photodiode.Be converted into a voltage that is used for controlling the resistance of p-i-n diode attenuator 102 by this microprocessors output of a digital to analog converter (DAC) 114.The resistance of this p-i-n diode attenuator 102 and RF drive level change inversely.This RF drive level is determined the optical modulation index (OMI) of laser 24.OMI also is called modulation depth (DOM).Correspondingly, thus the OMI level of this laser changes by the change on RF level or the amplitude and makes it get back to predeterminated level.
Fig. 4 also illustrates the second feedback path that can adopt in the present invention.Set up the proportional voltage of drive current of one and laser in the usual way by IPD monitor 108.Thereby the calibration of 108 pairs of these ratio-voltages of IPD monitor makes the light of it and laser be output into ratio.For example, scaling factor typically is chosen to 1 volt corresponding to 1 milliwatt.Thereby the voltage of this calibration is the indirect measurement of the optical output power of laser.The voltage of this calibration can also be used for determining that laser is in its efficient on operating temperature range.
Fig. 4 also adopts the 3rd feedback paths, and it is measured the RF drive level of amplifier reception behind RF and by microprocessor 112 value of storage this level and the memory 128 is compared.If this RF signal comprises the pilot tone that has when common employing frequency is piled up (frequency stacking), measure R F drive level easily.In frequency stacked system, the RF signal from two or more users that receives at optical node 12 places is shared a public bandwidth of returning, and piles up each other on these signal frequencies and sends on the bandwidth of a broad.For example, four users can respectively use the upstream bandwidth of a 35MHz, and this bandwidth is up-converted into the composite signal that comprises from 51 to 328MHz bandwidth.Correspondingly, optical node 12 can comprise a upconverter that is positioned at the laser module front.Common and upconverted composite signal sends pilot tone together, and it is used in the synchronous down-converted of head end, thereby eliminates any frequency error.For example, extend to from 51MHz the conventional system of 328MHz in bandwidth, pilot tone typically is positioned at the centre of this frequency band.
As shown in Figure 4, RF directional coupler 104 detects amplifier 34 receives behind the RF RF signal and it is directed to the band pass filter 116 of all RF components that remove except that pilot tone.The power level of pilot tone is measured by detector 117, converts digital value to and compares by the value of storing in microprocessor 112 and the memory by A/D converter 118.The measurement power level and the error correction voltage between the storing value of this pilot tone are used for controlling PIN diode attenuator 102 according to mode described above.
Memory for example in the nonvolatile memory storage microprocessor 112 be used for determining the various algorithms of feedback parameter.For example, as shown in Figure 4, can use flash memory 128 valuably, because it is mistake volatibility, rewritable and cheap.Owing to adopt recordable memory.These algorithms can be upgraded when needing.In addition, can in memory, store the data relevant, for example be exclusively used in the calibration curve (the definition gain is with the change of temperature) of the typical characteristics of the laser (and whole laser die block assembly) of actual use rather than average laser with laser characteristic.Thereby, in being installed to the return path generating laser before, can change and detect each individual laser package by making it stand increase on the temperature.Can measure as the laser diode gain of the function of temperature and with it and be stored in the flash memory, thus the suitable feedback parameter of the concrete laser customization that can be defined as detecting.
In Fig. 4, replenish flash memory so that the down loading updating information processing with static RAM (SRAM) 130.It is useful using static RAM (SRAM), because can not be simultaneously to the flash memory read and write.Thereby in order to upgrade under not break in service, the initial data of storage is transferred to static RAM (SRAM) 130 in the flash memory 128 when starting.Microprocessor is operated outside static RAM (SRAM) 130 scopes.Can send to flash memory 128 to new data more now.In this manner, needn't break in service, because microprocessor 112 is from static RAM (SRAM) 130 retrieve data during download process.
Claims (29)
1. optical transmitting set comprises:
A generation has the laser assembly of the light signal of a plurality of operating characteristics,
One by using the controller that at least one Control Parameter drives this laser assembly to this laser assembly, described controller comprises predetermined, that derive by experiment, that a plurality of operating characteristics and the Control Parameter of laser assembly an are associated database, described controller is adjusted at least one Control Parameter according to the data of extracting from this database at least in part, thereby optimizes at least one operating characteristic basically.
2. optical transmitting set as claimed in claim 1 also comprises a closed control circuit that contains described database.
3. optical transmitting set as claimed in claim 1, wherein, described controller comprises that a described database is positioned at look-up table wherein.
4. optical transmitting set as claimed in claim 1, wherein said operating characteristic comprises optical output power.
5. optical transmitting set as claimed in claim 4, wherein said operating characteristic also comprises BER, NPR and distortion.
6. optical transmitting set as claimed in claim 1, wherein said at least one Control Parameter comprise bias level, temperature, RF drive level, slope efficiency, tracking error control and threshold voltage.
7. optical transmitting set as claimed in claim 1, wherein said laser assembly comprises laser diode and photoelectric detector.
8. the method for the performance difference of each laser assembly of adopting at the optical transmitting set that is used for producing light signal of a consideration with a plurality of operating characteristics, described method comprises step:
For each laser assembly under in running order produces a plurality of operating characteristics of laser assembly and calibration curve that a plurality of Control Parameter of its application are associated,
For each laser assembly is provided with a controller, so that drive this laser assembly by at least one that this laser assembly is used in these Control Parameter,
For each laser assembly is set up communication between described controller and the calibration curve related with given laser assembly, thereby adjust Control Parameter so that optimize at least one operating characteristic of this given laser assembly basically according to this calibration curve.
9. method as claimed in claim 8, wherein, described operation spy comprises optical output power as characteristic.
10. method as claimed in claim 9, wherein said operating characteristic also comprises BER, NPR and distortion.
11. method as claimed in claim 8, wherein said Control Parameter comprise bias level, temperature, RF drive level, slope efficiency, tracking error control and threshold voltage.
12. one kind is applied in the optical node between a plurality of users in head end and the hybrid fiber/coax transmission system, described optical node comprises:
The O/E receiver is used for the light form downstream signal that termination is from the beginning received is converted to the downstream signal of the electric form that is sent at least one described user;
The O/E reflector is used for the upward signal from described user's electric form is converted to the upward signal of the light form that is sent to head end, and described O/E reflector comprises:
A laser module; And
At least one closed loop feedback path is used for the characteristic in response to the upward signal of the described electric form of measuring of parameter adjustment, so that be maintained at the value of an appointment by the light level of described laser module generation.
13. optical node as claimed in claim 12, wherein, described laser module comprises a laser cavity and a photodiode, and the parameter of described measurement is the current level that is produced by described photodiode.
14. optical node as claimed in claim 12, wherein, the parameter of described measurement is a laser drive current.
15. optical node as claimed in claim 12, wherein, the parameter of described measurement is the drive level of upward signal that is directed to the electric form of described laser module.
16. optical node as claimed in claim 12, wherein, described at least one closed loop feedback path comprises a plurality of closed loop feedback path, and the parameter of described measurement comprises current level and the laser drive current that is produced by described photodiode.
17. optical node as claimed in claim 12, wherein, described at least one closed loop feedback path comprises at least three closed loop feedback paths, the parameter of described measurement comprises the current level that is produced by described photodiode, laser drive current, and the drive level that is directed to the electric form upward signal of laser module.
18. optical node as claimed in claim 15, wherein, the upward signal of described electric form comprises the pilot tone that is used for the synchronizing frequency stacked signals, and the drive level of described measurement is the drive level of described pilot tone.
19. optical node as claimed in claim 12, wherein, described smooth feedback path comprises and is used for the parameter that will measure and predefined storing value compares and the microprocessor of the signal that is used to create a difference.
20. optical node as claimed in claim 19 also comprises being used in response to described difference signal, adjusts the adjusting device of drive level of the upward signal of the electric form be directed to laser module.
21. optical node as claimed in claim 20, wherein, described adjusting device comprises the p-i-p diode attenuator.
22. optical node as claimed in claim 21, wherein, described feedback path comprises that also the parameter that is used for measuring is converted to the analog to digital converter by the voltage of microprocessor identification.
23. optical node as claimed in claim 22, wherein, described feedback path also comprises the digital to analog converter that is used for described difference signal is converted to the voltage of being discerned by described adjusting device.
24. optical node as claimed in claim 19 also comprises being used to store by microprocessor being used for the parameter of more described measurement and the algorithm of predefined storing value.
25. optical node as claimed in claim 24, wherein, described memory is a flash memory.
26. optical node as claimed in claim 24, wherein, described algorithm comprises the calibration curve that the characteristic with laser module is associated with environmental parameter.
27. optical node as claimed in claim 16, wherein, described laser module characteristic is gain, and described environmental parameter is a temperature.
28. optical node as claimed in claim 12, wherein, the light level that is produced by described laser module is an optical level.
29. optical node as claimed in claim 12, wherein, the light level that is produced by described laser module is defined by optical modulation index.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US34079601P | 2001-12-12 | 2001-12-12 | |
| US60/340,796 | 2001-12-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1618152A true CN1618152A (en) | 2005-05-18 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNA028280091A Pending CN1618152A (en) | 2001-12-12 | 2002-12-12 | Return path transmitter having a closed laser control loop that is employed in a hybrid fiber / coax transmission system |
Country Status (2)
| Country | Link |
|---|---|
| EP (1) | EP1456917A4 (en) |
| CN (1) | CN1618152A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104604162B (en) * | 2012-08-28 | 2017-08-11 | 日本电气株式会社 | Optical sender and bias voltage control method |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5604757A (en) * | 1994-05-10 | 1997-02-18 | E-Tek Dynamics, Inc. | Multichannel, programmable laser diode power supply, stabilizer and controller |
| US6252692B1 (en) * | 1996-06-07 | 2001-06-26 | Nortel Networks Limited | Optical fibre transmission systems |
| IL121509A (en) * | 1997-08-11 | 2000-02-17 | Eci Telecom Ltd | Device and method for monitoring and controlling laser wavelength |
| US6122302A (en) * | 1997-12-10 | 2000-09-19 | Harmonic Inc. | Automatic compensation of CNR and OMI in a laser transmitter |
| US6356374B1 (en) * | 1998-10-09 | 2002-03-12 | Scientific-Atlanta, Inc. | Digital optical transmitter |
-
2002
- 2002-12-12 CN CNA028280091A patent/CN1618152A/en active Pending
- 2002-12-12 EP EP02798512A patent/EP1456917A4/en not_active Withdrawn
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104604162B (en) * | 2012-08-28 | 2017-08-11 | 日本电气株式会社 | Optical sender and bias voltage control method |
| US9735884B2 (en) | 2012-08-28 | 2017-08-15 | Nec Corporation | Optical transmitter and bias voltage control method |
Also Published As
| Publication number | Publication date |
|---|---|
| EP1456917A2 (en) | 2004-09-15 |
| EP1456917A4 (en) | 2005-12-07 |
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