CN1487349A - Light amplifier, gain-control method for light amplifier and electric circuit - Google Patents
Light amplifier, gain-control method for light amplifier and electric circuit Download PDFInfo
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- CN1487349A CN1487349A CNA031549926A CN03154992A CN1487349A CN 1487349 A CN1487349 A CN 1487349A CN A031549926 A CNA031549926 A CN A031549926A CN 03154992 A CN03154992 A CN 03154992A CN 1487349 A CN1487349 A CN 1487349A
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Abstract
The invention relates to an optical amplifier capable of achieving high-speed gain control in a wide dynamic range with a simpler constitution, gain control method and circuit for an optical amplifier. A gain control circuit of the optical amplifier includes a first photodetector for outputting a voltage having a linear relation with power of part of signal light to be inputted to the optical amplifier medium, a second photodetector for outputting a voltage having a linear relation with power of part of the signal light amplified in the optical amplifier medium, a comparator for outputting a difference between the voltages respectively outputted from the first and second photodetectors, and a drive circuit for supplying a desired drive current to a pumping light source in response to the voltage outputted from the comparator. Each of the first and second photodetectors includes a photoelectric conversion element for performing conversion into an electric current in response to inputted optical power, and an operational amplifier for converting the electric current outputted from the photoelectric conversion element into a voltage. Particularly, at least one of the first and second photodetectors includes an adjusting mechanism for adjusting an offset of the outputted voltage.
Description
Technical field
The present invention relates to a kind of image intensifer, a kind of gain control method of this kind image intensifer and a kind of gain control circuit of this kind image intensifer that can amplify flashlight (WDM flashlight) with the mutually different a plurality of channels of wavelength.
Background technology
In order to satisfy the needs that message capacity is increased, the application development in recent years of wavelength division multiplex (WDM) communication system is rapid.Simultaneously, for reliability and the efficient that improves network, optical add-drop multiplexer (OADM), optical crossover connector (OXC) that is used for telling or be inserted in the part WDM flashlight of transmission over networks etc. is being introduced in the WDM communication system.
The variation of channel quantity in the necessary flexible adaptation network of WDM communication system.Correspondingly,, as be widely used in the Erbium-Doped Fiber Amplifier (EDFA) of WDM communication system as network structure, the adaptability that channel quantity changes in pair network also will be arranged at image intensifer.And, along with the widespread use of above-mentioned WDM communication system, provide the image intensifer of low price of crucial importance to market.
Yet as a kind of method of controlling gain amplifier, traditional image intensifer adopts usually and uses a kind of logarithmic amplifier to come the method for calculated gains, as publication number be the Japanese unexamined patent of 2000-40847 disclosed.Particularly, use the automatic gain control (AGC) of logarithmic amplifier calculated gains to carry out according to following principle.
Particularly, the gain of following formula (1) expression image intensifer:
G(dB)＝P
OUT(dBm)-P
IN(dBm) (1)
Here, G represent the gain (unit: dB), P
INThe logarithm value of expression input optical power (unit: dBm), P
OUTLogarithm value (the unit: dBm) of expression Output optical power.
Input side at image intensifer, the proportional voltage of luminous power of one of input side photodetector output and amplification forward part light signal, the input side logarithmic amplifier carries out log-transformation (that is output voltage V of input side logarithmic amplifier, to the voltage of input side photodetector output
1The logarithm value of the luminous power that is detected with the input side photodetector is proportional).In contrast, one of outgoing side photodetector output and the proportional voltage of amplification rear section light signal luminous power, and the outgoing side logarithmic amplifier also carries out log-transformation (that is output voltage V of outgoing side logarithmic amplifier, to the output voltage of outgoing side photodetector
2, the logarithm value of the luminous power that is detected with the outgoing side photodetector is mutually proportional).Then, by with a difference calculator with the voltage V that is obtained
1And V
2Thereby subtract each other the gain that detects image intensifer.With a comparer gain and the target gain that is detected compared, by for example adjusting pumping light power the gain of image intensifer is controlled, so that gain that is detected and target gain are each other about equally.
Simultaneously, in the example that image intensifer is carried out automatic electric-level control (ALC), the gain of image intensifer is surveyed according to said method and is obtained, and Output optical power calculates by following formula (2):
P
OUT(dBm)＝G(dB)+P
IN(dBm) (2)
Then, thus obtained Output optical power and target Output optical power are compared, pumping light power or other luminous powers are controlled, so that above-mentioned performance number is equal to each other.
Summary of the invention
By studying above-mentioned prior art, the present inventor has found following problems.
In the gain control of traditional image intensifer, the output voltage of photodetector carries out log-transformation by logarithmic amplifier, and gain is surveyed by using very feasible difference calculator to carry out.Yet in electronic devices and components, logarithmic amplifier is relatively costly.And the nonlinear Control circuit that contains the control circuit formation of logarithmic amplifier is difficult to design.For example, when using logarithmic amplifier, the gain of control circuit is owing to the input optical power of being surveyed may fluctuate (that is, the gain of control circuit increases along with the minimizing of the luminous power that is input to photodetector).Correspondingly, under this kind situation, if quicken, it is very unstable that control circuit may become, and reaches high speed gain control in the very wide dynamic range so be difficult in.
The invention solves foregoing problems.One of purpose of the present invention provides a kind of image intensifer that can reach the structure simpler (cost is lower) of high speed gain control in a wideer dynamic range, the gain control method of this kind image intensifer, and a kind of gain control circuit that can be used for this kind image intensifer.
Image intensifer of the present invention comprises an image intensifer medium, a pump light source, an input side coupling mechanism (first coupling mechanism) and an outgoing side coupling mechanism (second coupling mechanism) and a gain control circuit that the image intensifer medium is clipped in the middle.The image intensifer medium comprises, for example, and Er-doped fiber (EDF).Pump light source provides the pump light of predetermined wavelength to the image intensifer medium.The input side coupling mechanism comprises the tributary port (branch port) of the part of a light signal that is used to separate input image intensifer medium.The outgoing side coupling mechanism comprises a tributary port that is used for being separated in the part of the light signal that the image intensifer medium amplifies.And gain control circuit is controlled the gain of image intensifer by the difference information between the performance number of using the light of being separated by input side coupling mechanism and outgoing side coupling mechanism.Here, the gain control that gain control circuit carried out comprises automatic gain control at least.
Gain control circuit comprises an input side photodetector (first photodetector), an outgoing side photodetector (second photodetector), a comparer (being included in the control system) and a driving circuit.The voltage that the power of the light that one of input side photodetector output and input side coupling mechanism are separated has linear relationship.The voltage that the power of the light that one of outgoing side photodetector output and outgoing side coupling mechanism are separated has linear relationship.The voltage difference of the magnitude of voltage that one of comparer output obtains from input side photodetector and outgoing side photodetector respectively.And the output voltage of driving circuit response comparator to pump light source, provides desired drive current as laser diode.
Especially, for image intensifer being carried out gain control, the input optical power P of at least one in defining about input side photodetector and outgoing side photodetector
iWith output voltage V
oBetween the function (V of linear relationship
o=aP
i+ b) in, gain control circuit is adjusted slope a and intercept b.At this,, be preferably in the luminous power of the noise light (mainly being ASE light) that is contained in the consideration image intensifer output light when adjusting slope and intercept in order only the wdm optical signal that will amplify to be carried out gain control.And, change for fear of dynamic gain, preferably the response time in the gain control circuit was made as one second or shorter.
Except said structure, image intensifer of the present invention preferably also comprises a temperature sensor that is used to measure the environment temperature of input side photodetector and outgoing side photodetector environment of living in.If environment temperature changes, the linear relationship between input optical power and the output voltage just might also change owing to the temperature drift in the gain control circuit.Therefore, because when the change in gain that temperature variation causes just can change by correct monitor temperature, adjust the slope of linear relationship or intercept and effectively suppressed (that is, the voltage of comparer being supplied with driving circuit according to the measurement result of temperature sensor is suitably proofreaied and correct).
And image intensifer of the present invention can also contain a gainequalizer between the signal outlet terminal of image intensifer medium and outgoing side coupling mechanism.By place gainequalizer between image intensifer medium and outgoing side coupling mechanism, the light that the outgoing side coupling mechanism is separated (detected object of outgoing side photodetector) is eliminated (lack of uniformity that gains between respective channel is minimized) to the dependence of wavelength.Correspondingly, the channel quantity that just might not consider to introduce the WDM flashlight of image intensifer medium changes, and the WDM signal gain is carried out constant control.
With simpler structure with at a high speed the image intensifer with above-mentioned structure is carried out gain control for example in the gain control circuit of automatic gain control in (being gain control circuit of the present invention), input side photodetector, outgoing side photodetector and comparer preferably contain following circuit component respectively.Particularly, the input side photodetector contains a photo-electric conversion element (first photo-electric conversion element), as phototransformation that the input side coupling mechanism is separated photodiode for the electric current relevant with its power, and the current conversion with photo-electric conversion element output is the operational amplifier (first operational amplifier) of voltage, and this operational amplifier can be adjusted the skew of output voltage.The outgoing side photodetector contains a photo-electric conversion element (second photo-electric conversion element), be converted to the photodiode of the electric current relevant with its power as the light that the outgoing side coupling mechanism is separated, and the current conversion with photo-electric conversion element output is the operational amplifier (second operational amplifier) of voltage, and this operational amplifier can be adjusted the skew of output voltage.Simultaneously, comparer contains a differential amplifier, and it receives and is included in the voltage that the operational amplifier in input side photodetector and the outgoing side photodetector is exported respectively.Differential amplifier is input to driving circuit with the difference of the output voltage of input side photodetector and outgoing side photodetector.The voltage that driving circuit is exported according to comparer (voltage difference) provides drive current to pump light source such as laser diode.
Particularly, in the gain control circuit of the present invention, input side photodetector and outgoing side photodetector have at least one to contain an adjustment mechanism of adjusting offset voltage at least.In other words, in gain control circuit, has one in input side photodetector and the outgoing side photodetector at least to definition input optical power P
iAnd output voltage V
oBetween the function (V of linear relationship
o=aP
i+ b) in the b of intercept at least among slope a and the intercept b adjust the corresponding offset voltage of intercept b wherein.
Here, the response time in the gain control circuit preferably also was made as one second or shorter dynamic change to avoid gaining.And in order only the wdm optical signal that will amplify to be carried out gain control, above-mentioned offset voltage adjustment is to carry out under the situation of the noise light (mainly being ASE light) that contained in having considered image intensifer output light.
Except said structure, gain control circuit of the present invention preferably also contains a temperature sensor that is used for measuring the environment temperature of input side photodetector and at least one environment of living in of outgoing side photodetector, to realize constant gain control at temperature variation.
Below, gain control method of the present invention is applicable to that the image intensifer to amplify the WDM flashlight by the image intensifer medium transmission by the pump light that predetermined wavelength is provided from pump light source carries out gain control.
In gain control method of the present invention, be used to define input optical power P
iWith output voltage V
oBetween the function (V of linear relationship
o=aP
i+ b) in, slope a and intercept b at first the input side photodetector of the part signal light by being used for receiving input image intensifer medium and at least one of outgoing side photodetector that is used for the part signal light that the reception amplifier medium amplified adjust.Then, this information subtend pump light source of difference with the voltage of being exported from input side photodetector and outgoing side photodetector respectively provides the driving circuit of drive current to control.
At this, in gain control method of the present invention, in order to realize the stable control of gain at temperature variation, driving circuit is this information of voltage difference according to the voltage of being exported from input side photodetector and outgoing side photodetector respectively, and the ambient temperature information of at least one environment of living in is controlled in input side photodetector and the outgoing side photodetector.And constant for the gain amplifier that makes the image intensifer medium, the voltage that going back the subtend driving circuit is provided is adjusted.For fear of the dynamic change of gain, be set in one second or shorter from the photodetection of input side photodetector and outgoing side photodetector to the response time the output adjustment of pump light source.At least one in slope and the intercept is adjusted, to reduce the influence of the noise light that is contained in the image intensifer output light, effect can be better.
Description of drawings
Fig. 1 is the structural drawing of first embodiment of image intensifer of the present invention.
Fig. 2 is the basic block diagram of gain control circuit of the present invention.
Fig. 3 is a design sketch of explaining gain control method of the present invention.
Fig. 4 is the structural drawing of second embodiment of image intensifer of the present invention.
Fig. 5 is the structural drawing that shows the 3rd embodiment of image intensifer of the present invention.
Embodiment
Now, describe the preferred embodiment etc. of image intensifer of the present invention in detail referring to Fig. 1 to Fig. 5.Note that identical member is marked with identical Reference numeral in the description process of accompanying drawing, the explanation of repetition will be omitted at this.
Fig. 1 is the structural drawing of first embodiment of image intensifer of the present invention.As shown in Figure 1, the image intensifer of first embodiment comprises an input side coupling mechanism 110a, an optoisolator 120a, a multiplexer 130, article one, as the Er-doped fiber (EDF) 140 of image intensifer medium, another optoisolator 120b and an outgoing side coupling mechanism 110b, all elements are provided with to outlet terminal 100b from entry terminal 100a according to enumerating order.And this image intensifer also contains a laser diode (LD) 210, and it is the pump light source that the pump light of predetermined wavelength is provided to EDF140, and a gain control circuit.Gain control circuit contains an input side photodetector 200a, an outgoing side photodetector 200b, a comparer 230 that is included in the agc circuit (control system) 240 that is used for carrying out automatic gain control, and a driving circuit 220.
Input side coupling mechanism 110a contains the tributary port of the part of the WDM flashlight that a guiding takes in from entry terminal 100a to gain control circuit.Simultaneously, outgoing side coupling mechanism 110b contains the tributary port of the part of the WDM flashlight that a guiding amplified by EDF 140 to gain control circuit.
Optoisolator 120a has the WDM flashlight by input side coupling mechanism 110a is transferred to EDF 140, blocks the effect from the light of EDF 140 simultaneously.In contrast, optoisolator 120b has the WDM flashlight that EDF 140 is amplified and is transferred to outgoing side coupling mechanism 110b, blocks the effect from the light of outgoing side coupling mechanism 110b simultaneously.
As mentioned above, gain control circuit contains input side photodetector 200a, outgoing side photodetector 200b, comparer 230 and driving circuit 220.The power P of a light that is separated with input side coupling mechanism 110a of input side photodetector 200a output
iVoltage with linear relationship.Simultaneously, the power P of a light that is separated with outgoing side coupling mechanism 110b of outgoing side photodetector 200b output
oVoltage with linear relationship.Be included in one of comparer 230 output in the agc circuit 240 respectively from the voltage difference of the voltage of input side photodetector 200a and outgoing side photodetector 200b output.And the output voltage of driving circuit 220 response comparators 230 provides desired drive current to pump light source LD 210.
In this structure, gain control circuit be adjusted into the definition with input side photodetector 200a and outgoing side photodetector 200b at least one relevant input optical power P
iWith output voltage V
oBetween the function (V of linear relationship
o=aP
i+ slope a and intercept b in b).At this, in order only the WDM flashlight that will amplify to be carried out gain control, when being adjusted, slope and intercept preferably consider the luminous power of the noise light (mainly being ASE light) that contained in the image intensifer output light.And the dynamic change for fear of gain preferably is made as the response time in this gain control circuit one second or shorter.
Next, Fig. 2 is the basic block diagram of gain control circuit of the present invention.In gain control circuit shown in Figure 2, input side photodetector 200a contains the light that input side coupling mechanism 110a is separated, and (luminous power is P
i) being converted to the photodiode PD 201a of electric signal, the offset voltage that can dynamically adjust offset voltage is adjusted machine-processed 203a, and one is used to receive offset voltage and from electric signal and the output and the input optical power P of institute of PD 201a
iVoltage V with linear relationship
1Operational amplifier 202a.
Comparer 230 contains a reception respectively from the voltage V of input side photodetector 200a and outgoing side photodetector 200b output
1And V
2And export its difference V
3Differential amplifier 231.The voltage difference V that driving circuit 220 will be exported with comparer 230
3Relevant drive current offers LD 210.Like this, power is P
PPump light be provided to EDF 140 via multiplexer 130 from LD 210.
Particularly, before the amplification, part signal light is separated by the input side coupling mechanism 110a that is positioned at the image intensifer input side, the voltage V that the power of the light that input side photodetector 200a exports and separated has linear relationship
1In contrast, after the amplification, part optical signals is separated by the outgoing side coupling mechanism 110b that is positioned at the image intensifer outgoing side, the voltage V that the power of the light that outgoing side photodetector 200b exports and separated has linear relationship
2Voltage V from corresponding light electric explorer 200a and 200b output
1And V
2Be input in the differential amplifier 231 in the comparer 230 voltage difference V respectively
3I.e. output since then.Here, for example, can be with operational amplifier, use the differential amplifier etc. of operational amplifier to compare device 230.And driving circuit 220 is according to the voltage difference V of comparer 230 outputs
3The pump energy P of control pump light source LD 210
P, the gain of image intensifer is controlled thus.
Next, the automatic gain control (that is gain control method of the present invention) of gain control circuit shown in Figure 2 described.
At first, the output voltage V of input side photodetector 200a
1Output voltage V with outgoing side photodetector 200b
2Represent by following formula (3) and (4) respectively:
V
1＝R
1·T
1·P
i+V
o1 (3)
V
2＝R
2·T
2·P
o+V
o2 (4)
Here, T
1And T
2The transfer ratio (transmittance) of expression input and output side coupling mechanism 110a and 110b respective branch port, P
iAnd P
oThe optical power value that expression corresponding light electric explorer 200a and 200b are detected, V
O1And V
O2The offset voltage (intercept) of expression corresponding light electric explorer 200a and 200b, R
1And R
2Expression slope (product of photodetector conversion ratio (A/W) and resistance (Ω)).
Simultaneously, the output voltage difference V of the differential amplifier 231 in the comparer 230
3Represent by following formula (5):
V
3＝K(V
1-V
2) (5)
At this, K represents the gain of differential amplifier 231.
The gain K that supposes differential amplifier 231 is unlimited (that is, desirable comparer) and V
O1=V
O2, then can derive following formula (6) to formula (5) by aforementioned formula (3):
P
OUT/P
IN＝(R
1·T
1)/(R
2·T
2)＝G (6)
Here, G represents the gain of image intensifer.
Correspondingly, ideally (in this case, the gain K of differential amplifier 231 is unlimited), the gain G of image intensifer is by R
1And R
2And the transfer ratio T of input and output side coupling mechanism 110a and 110b respective branch port
1And T
2Decision.Yet in the reality, the gain of differential amplifier 231 is not unlimited.Therefore, in gain control method of the present invention, by adjusting the offset voltage V in formula (3) and the formula (4)
O1And V
O2(offset voltage is adjusted machine-processed 203a and 203b) thus in very wide dynamic range, reach the automatic control of gain.
Here, in gain control circuit shown in Figure 2, can clearly be seen that the variation of light amplifier gain can also be by adjusting and input optical power P from aforementioned formula (6)
iAnd output voltage V
oBetween linear relationship (V
o=aP
i+ b) the corresponding R of slope
1And R
2Between ratio, or by adjusting the transfer ratio T of input and output side coupling mechanism 110a and 110b respective branch port
1And T
2Between ratio reach.In this case, also need to adjust the respective offsets voltage V of photodetector 200a and 200b
O1And V
O2In at least one.In any method of adjustment, different with traditional gain control circuit, this gain control circuit does not need logarithmic amplifier.Therefore, gain control circuit of the present invention can be realized by simpler structure (with lower cost).
Simultaneously, in amplification process, image intensifer usually also can output noise light (mainly being ASE light).Therefore, the light exported of image intensifer had both contained the WDM flashlight that noise light also contains amplification.In image intensifer,, need to eliminate the influence of the noise light that contained in the output light to gain control for the gain amplifier of control signal light accurately.In order to eliminate the influence of noise light, need be from the output voltage V of outgoing side photodetector 200b
2In deduct the difference that equates with noise light power correspondent voltage.Or rather, by adjusting intercept (the offset voltage V in the formula (4)
O2) eliminate the influence of noise light.
Next, Fig. 3 is the figure that explains gain control method effect of the present invention.Fig. 3 is that explanation can be by the relativity shift voltage V of corresponding adjustment input side photodetector 200a and outgoing side photodetector 200b
O1And V
O2Thereby realize the figure of gain control (automatic gain control) in very wide dynamic range.Here, in Fig. 3, when curve G100 is illustrated in the relative adjustment of carrying out offset voltage, the relation between flashlight power input (dBm) and the flashlight gain (dB), the described relation when curve G200 represents that not carrying out offset voltage adjusts.
Be appreciated that from Fig. 3, when not carrying out the adjustment of offset voltage, (curve G200: the situation that does not have relative different between the respective offsets voltage of input side photodetector 200a and outgoing side photodetector 200b) in gain control circuit shown in Figure 2, flashlight power input (dBm) reduces manyly more, and flashlight gain (dB) increases manyly more.On the contrary, in the situation of the offset voltage of the offset voltage of outgoing side photodetector 200b relatively being adjusted to input side photodetector 200a (curve G100), flashlight gain (dB) can almost obtain constant control regardless of the variation of flashlight power input (dBm) in the gain control circuit shown in Figure 2.Therefore, the relative adjustment between input side photodetector 200a and outgoing side photodetector 200b offset voltage is vital for obtaining the high precision gain control in very wide dynamic range.In other words, consideration is input to the power P of the light of corresponding light electric explorer 200a and 200b
iWith the plan output voltage V
oBetween linear relationship (V
o=aP
i+ to adjust intercept b b) and relatively be vital.
Note that and to carry out relative the adjustment to the offset voltage of corresponding light electric explorer 200a and 200b.Therefore, if the offset voltage of at least one is adjusted with respect to another offset voltage among photodetector 200a and the 200b, just enough.
Fig. 4 is the structural drawing of second embodiment of image intensifer of the present invention.The image intensifer of second embodiment contains an input side coupling mechanism 110a, an optoisolator 120a, a multiplexer 130, an Er-doped fiber (EDF) 140 that is used as the image intensifer medium, another optoisolator 120b and an outgoing side coupling mechanism 110b, similar to first embodiment, these elements are provided with to output terminal 100b from input end 100a according to enumerating order.And image intensifer also contains a laser diode (LD) 210, and it is the pump light source that the pump light of predetermined wavelength is provided to EDF140, and a gain control circuit of controlling light amplifier gain such as automatic gain control.And, this gain control circuit contains an input side photodetector 200a, an outgoing side photodetector 200b, a comparer 230 that is included in the agc circuit (control system) 250 that carries out automatic gain control, and a driving circuit 220.Structural similarity in the gain control circuit shown in its basic structure and Fig. 2.
Particularly, the image intensifer of second embodiment and the difference of first embodiment be, this image intensifer also has a temperature sensor 260 that is used for measuring the environment temperature of input side photodetector 200a and at least one environment of living in of outgoing side photodetector 200b.Agc circuit 250 among second embodiment has a structure according to the measurement result continuous correction voltage of temperature sensor 260, and this voltage offers driving circuit 220 by the comparer 230 that is included in the agc circuit 250.
When temperature variation, because the temperature drift in the gain control circuit, the relation of formula (3) and formula (4) representative also might change.If the relation of formula (3) and formula (4) representative changes, the gain amplifier of image intensifer also can change.Therefore, the image intensifer of second embodiment (Fig. 4) contains a temperature sensor, so that at temperature variation control is stablized in gain.And, according to measurement result, at least one slope or intercept in agc circuit 250 adjustment formula (3) and the formula (4).Or rather, have the offset voltage that is used for adjusting offset voltage (this offset voltage is corresponding to the intercept of formula (3) and formula (4)) in input side photodetector 200a and outgoing side photodetector 200b one or two of gain control circuit shown in Figure 2 and adjust machine-processed 203a and 203b.Correspondingly, the machine-processed 203a of described adjustment carries out relative the adjustment with 203b by agc circuit 250 and (here, needn't adjust two offset voltages; If an offset voltage is fixed, then only adjust another offset voltage and get final product).
Next, Fig. 5 is the structural drawing of the 3rd embodiment of image intensifer of the present invention.The image intensifer of the 3rd embodiment also contains an input side coupling mechanism 110a, an optoisolator 120a, a multiplexer 130, Er-doped fiber (EDF) 140 as the image intensifer medium, another optoisolator 120b and an outgoing side coupling mechanism 110b, similar with second embodiment to first, these elements are provided with to output terminal 100b from input end 100a according to enumerating order.And this image intensifer also contains a laser diode (LD) 210, and it is the pump light source that the pump light of predetermined wavelength is provided to EDF 140, and a gain control circuit of controlling light amplifier gain such as automatic gain control.And, this gain control circuit contains an input side photodetector 200a, an outgoing side photodetector 200b, a comparer 230 that is included in the agc circuit (control system) 270 of carrying out automatic gain control, and a driving circuit 220.Structural similarity in its basic structure and the gain control circuit shown in Figure 2.
Particularly, the image intensifer of the 3rd embodiment and the difference of second embodiment are that this image intensifer also contains one and places the signal output part of EDF 140 and the gainequalizer (GEQ) 150 between the outgoing side coupling mechanism 110b.In the 3rd embodiment, agc circuit 170 be configured to monitor the flashlight before amplifying and amplify after flashlight, and adjust the offset voltage of input side photodetector 200a and outgoing side photodetector 200b continuously.Yet agc circuit 270 also can adopt the akin structure with first embodiment, and the offset voltage of corresponding light electric explorer 200a and 200b is adjusted in advance.
Gain as the EDF 140 of image intensifer medium has dependence to wavelength.Therefore, because the lack of uniformity of the WDM flashlight gain amplifier that causes of wavelength, the image intensifer of the 3rd embodiment contains a GEQ 150 in order to reduce, and the shape of its loss spectra is identical with the gain spectral of EDF140.Preferably GEQ 150 is placed between the signal output part and outgoing side coupling mechanism 110b of EDF 140.If GEQ 150 is arranged on the downstream (between outgoing side coupling mechanism 110b and output terminal 100b) of outgoing side coupling mechanism 110b, perhaps without GEQ 150, although the WDM flashlight of input image intensifer demonstrates consistent level in the channel of respective wavelength, the light that outgoing side coupling mechanism 110b is separated (detected object of outgoing side photodetector 200b) is still unbalanced at corresponding interchannel.In this case, the gain of control image intensifer makes that the average gain of WDM flashlight is desired value.Correspondingly, the gain of the flashlight on channel may be different from the average gain of WDM flashlight on a plurality of channels.Therefore, if the channel quantity of the WDM flashlight of being imported changes, so, the average gain of WDM signal has also changed.Therefore, gain control circuit will be controlled the gain of image intensifer, so that the average gain that changes has a desired value.As a result, the gain of the WDM flashlight in the respective channel can obtain changing.
Simultaneously, in the image intensifer of the 3rd embodiment, as shown in Figure 5, GEQ 150 places between EDF 140 and the outgoing side coupling mechanism 110b.Therefore, the light that outgoing side coupling mechanism 110b is separated (detected object of outgoing side photodetector 200b) is eliminated (promptly for the dependence of wavelength, the lack of uniformity of each interchannel gain is reduced), therefore, although the quantity of WDM flashlight channel changes, the gain of the WDM flashlight of transmission can be controlled consistently on EDF 140.
Here, if the transfer ratio value T of the respective branch port of input side coupling mechanism and outgoing side coupling mechanism 110a and 110b
1And T
2Wavelength is had dependence, and the gain of each interchannel of the WDM flashlight of being imported will become unbalanced (referring to formula (3) or formula (4)).For example, when the bandwidth of signal wavelength is 30nm, for the change in gain between respective channel being controlled at+1dB or littler, need be with the transfer ratio T of the tributary port of input side coupling mechanism 110a
1Transfer ratio T to the tributary port of the dependence of wavelength and outgoing side coupling mechanism 110b
2Difference to the dependence of wavelength is controlled at ± 1dB/30nm or littler.And, channel wavelength not being produced dependence for the gain of controlling each interchannel consistently, input side coupling mechanism 110a and outgoing side coupling mechanism 110b must adopt transfer ratio value T
1And T
2Wavelength is not had and rely on or be the tributary port of identical value.
Such image intensifer is applicable to the optical communication system of transmission WDM flashlight, more specifically, is applicable to the system with the device that carries out channel separation or channel insertion in the WDM flashlight.
As mentioned above, according to the present invention, in the photodetector that the part of the flashlight after flashlight before amplifying and the amplification is surveyed as electronic signal, carry out prior or adjustment continuously to the linear relationship between input optical power and the output voltage, thereby the output valve of photodetector is used as the input data of gain control.Like this, just can not resemble needs logarithmic amplifier to realize that (it is constant making the gain in the control circuit to linearity control circuit the prior art, institute's input optical power is not had dependence), and carry out high speed gain control with simpler structure (with lower cost).
Claims (22)
1. image intensifer comprises:
An image intensifer medium;
The pump light source that the pump light of predetermined wavelength is provided to described image intensifer medium;
First coupling mechanism that is used to separate the part of the flashlight of importing described image intensifer medium;
Second coupling mechanism that together described image intensifer medium is clipped in the middle with described first coupling mechanism, described second coupling mechanism is separated in the part of institute's amplifying signal light in the described image intensifer medium; And
The gain control circuit that the relevant information of the power of the light that use and described first and second coupling mechanisms are separated is respectively controlled the gain of described image intensifer,
Wherein, described gain control circuit comprises:
First photodetector of the voltage that power that is used to export the light of separating with described first coupling mechanism is linear;
Second photodetector of the voltage that power that is used to export the light of separating with described second coupling mechanism is linear;
A comparer that is used to export the voltage difference between the voltage that described first and second photodetectors export respectively; And,
The output voltage of a described comparer of response provides the driving circuit of desired drive current to described pump light source;
Wherein, described gain control circuit has a kind of by adjusting the definition input optical power P relevant with described first and second photodetectors
iAnd output voltage V
oBetween the function (V of linear relationship
o=aP
i+ b) in slope a and intercept b and carry out the structure of gain control.
2. image intensifer as claimed in claim 1, wherein, described first photodetector comprises:
First photo-electric conversion element that is used for the light that described first coupling mechanism is separated is converted to the electric current relevant with its power; And
One is used for the current conversion that described first photo-electric conversion element is exported is first operational amplifier of voltage;
Wherein, described second photodetector comprises:
Second photo-electric conversion element that is used for the light that described second coupling mechanism is separated is converted to the electric current relevant with its power; And
One is used for the current conversion that described second photo-electric conversion element is exported is second operational amplifier of voltage,
Wherein, at least one in described first and second photodetectors comprises an adjustment mechanism that is used to adjust the skew of the voltage that will export.
3. image intensifer as claimed in claim 1, the described comparer in the wherein said gain control circuit contain a differential amplifier that is used for receiving the voltage that described first and second operational amplifiers that are included in described first and second photodetectors respectively export.
4. image intensifer as claimed in claim 1 also contains a temperature sensor that is used for measuring the environment temperature of described first and second at least one environment of living in of photodetector,
Wherein, the linear relationship between luminous power and the output voltage is proofreaied and correct according to the measurement result of described temperature sensor in described first and second photodetectors.
5. image intensifer as claimed in claim 1 is provided with a gainequalizer between the signal output part of described image intensifer medium and described second coupling mechanism.
6. image intensifer as claimed in claim 1, wherein, the response time of described gain control circuit is one second or shorter.
7. image intensifer as claimed in claim 1, wherein, described gain control circuit carries out automatic gain control.
8. image intensifer as claimed in claim 1 wherein, is adjusted slope and intercept, with the influence of the noise light that contained in the light of eliminating the output of described image intensifer.
9. image intensifer as claimed in claim 1, wherein, the transfer ratio T of the tributary port in described first photodetector
1To the dependence of wavelength and the transfer ratio T of the tributary port in described second photodetector
2The absolute value of the difference between the dependence of wavelength when bandwidth is 30nm, is ± 1dB or littler.
10. the gain control method of image intensifer, this image intensifer is amplified in the mutually different flashlight of the wavelength that transmits on the image intensifer medium by the pump light of predetermined wavelength is provided from pump light source, and described gain control method comprises the steps:
Adjust definition receive the flashlight that will import described image intensifer medium a part first photodetector and receive in second photodetector of a part of described image intensifer medium institute amplifying signal light at least one input optical power P
iWith output voltage V
oBetween the function (V of linear relationship
o=aP
i+ b) among slope a and the intercept b at least one; And
Use the difference information of the voltage that described first and second photodetectors export respectively, control provides the driving circuit of drive current to described pump light source.
11. gain control method as claimed in claim 10, wherein, the ambient temperature information of at least one environment of living in is controlled driving circuit in the difference information of the voltage of exporting respectively according to first and second photodetectors and first and second photodetectors.
12. gain control method as claimed in claim 10 wherein, is adjusted so that the gain amplifier of image intensifer amplification medium is constant the voltage that will offer driving circuit.
13. gain control method as claimed in claim 10 wherein, detects light from first and second photodetectors and was made as one second or shorter to the response time that the output of described pump light source is adjusted.
14. gain control method as claimed in claim 10 wherein, is adjusted the influence of the noise light that is contained in the light with the output of elimination image intensifer to any one in slope and the intercept.
15. gain control method as claimed in claim 10, wherein, the transfer ratio T of the tributary port in described first photodetector
1To the dependence of wavelength and the transfer ratio T of the tributary port in described second photodetector
2Is 1dB or littler in bandwidth to the absolute value of the difference between the dependence of wavelength during for 30nm.
16. gain control method as claimed in claim 10 wherein, is amplified and the part optical signals that detected by described second photodetector has reduced the lack of uniformity of each wavelength by described image intensifer medium.
17. gain control circuit is used for being amplified in by the pump light that predetermined wavelength is provided from pump light source the image intensifer of the mutually different flashlight of wavelength that the image intensifer medium transmits, described gain control circuit comprises:
The power of the part of a flashlight that is used to export and intend importing described image intensifer medium has first photodetector of the voltage of linear relationship, described first photodetector contain one will input part signal light in it be converted to first photo-electric conversion element of the electric current relevant with its power, and output current with described first photo-electric conversion element is converted to first operational amplifier of voltage;
One is used to export second photodetector that has the voltage of linear relationship with the power of the part of described image intensifer medium institute amplifying signal light, described second photodetector contains second photo-electric conversion element that the part with institute's amplifying signal light is converted to the electric current relevant with its power, and output current with described second photo-electric conversion element is converted to second operational amplifier of voltage;
A comparer that is used to export the voltage difference of the voltage that described first and second photodetectors export respectively, described comparer contains the differential amplifier that a reception is included in the output voltage of first and second operational amplifiers in described first and second photodetectors respectively; And,
The output voltage of a described comparer of response provides the driving circuit of desired drive current to described pump light source,
Wherein, at least one also contains the adjustment mechanism that at least one intends the skew of output voltage of adjusting in described first and second photodetectors.
18. gain control circuit as claimed in claim 17, wherein, described gain control circuit had one second or the shorter response time.
19. gain control circuit as claimed in claim 17, wherein, described gain control circuit is carried out automatic gain control.
20. gain control circuit as claimed in claim 17, wherein, the described mechanism of adjusting is adjusted the skew of voltage to eliminate the influence of the noise light that is contained in the described image intensifer output light.
21. gain control circuit as claimed in claim 17, also contain a temperature sensor that is used for measuring the environment temperature of described first and second at least one environment of living in of photodetector, wherein, the difference information of the voltage of exporting respectively according to described first and second photodetectors and the measurement result of described temperature sensor are controlled described driving circuit.
22. gain control circuit as claimed in claim 17, wherein, the transfer ratio T of the tributary port in described first photodetector
1To the dependence of wavelength and the transfer ratio T of the tributary port in described second photodetector
2Is 1dB or littler at the width of wavelength to the absolute value of the difference between the dependence of wavelength during for 30nm.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP255000/2002 | 2002-08-30 | ||
| JP2002255000A JP4126994B2 (en) | 2002-08-30 | 2002-08-30 | Optical amplifier, optical amplifier gain control method, and optical amplifier gain control circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1487349A true CN1487349A (en) | 2004-04-07 |
| CN1318909C CN1318909C (en) | 2007-05-30 |
Family
ID=34179481
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB031549926A Expired - Fee Related CN1318909C (en) | 2002-08-30 | 2003-08-26 | Light amplifier, gain-control method for light amplifier and electric circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1318909C (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014075271A1 (en) * | 2012-11-15 | 2014-05-22 | 华为技术有限公司 | Optical amplifier control method and device and optical amplifier |
| CN108956650A (en) * | 2017-05-25 | 2018-12-07 | 北京君和信达科技有限公司 | Detector gain method of automatic configuration, device, system and storage medium |
| CN113541815A (en) * | 2021-09-16 | 2021-10-22 | 香港中文大学（深圳） | Resonant optical communication device and method based on gain control |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02308581A (en) * | 1989-05-24 | 1990-12-21 | Furukawa Electric Co Ltd:The | Light amplification |
| SE514609C2 (en) * | 1996-09-13 | 2001-03-19 | Ericsson Telefon Ab L M | System and method for controlling the output power of an optical amplifier |
| GB2322228A (en) * | 1997-02-17 | 1998-08-19 | Northern Telecom Ltd | Optical amplifiers and WDM transmission systems |
| JP2000040847A (en) * | 1998-07-23 | 2000-02-08 | Nippon Telegr & Teleph Corp <Ntt> | Optical amplifier |
| US6163399A (en) * | 1998-12-08 | 2000-12-19 | Nortel Networks Limited | Method and apparatus for suppressing transients in optical amplifiers |
| US6366395B1 (en) * | 2000-03-30 | 2002-04-02 | Nortel Networks Limited | Optical amplifier gain control |
-
2003
- 2003-08-26 CN CNB031549926A patent/CN1318909C/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014075271A1 (en) * | 2012-11-15 | 2014-05-22 | 华为技术有限公司 | Optical amplifier control method and device and optical amplifier |
| CN108956650A (en) * | 2017-05-25 | 2018-12-07 | 北京君和信达科技有限公司 | Detector gain method of automatic configuration, device, system and storage medium |
| CN108956650B (en) * | 2017-05-25 | 2021-09-24 | 北京君和信达科技有限公司 | Detector gain automatic configuration method, device and system and storage medium |
| CN113541815A (en) * | 2021-09-16 | 2021-10-22 | 香港中文大学（深圳） | Resonant optical communication device and method based on gain control |
| CN113541815B (en) * | 2021-09-16 | 2021-12-21 | 香港中文大学（深圳） | Resonant optical communication device and method based on gain control |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1318909C (en) | 2007-05-30 |
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