KR101459342B1 - Noise suppression apparatus for injection seeded optical source and wavelength division multiplexed-passive optical network system having the same - Google Patents

Abstract

Disclosed are a noise suppressing apparatus for an injection seeded optical source and a WDM-PON system including the same. The noise suppressing apparatus according to one embodiment of the present invention efficiently suppresses noises by a feed-forward method by controlling a gain of an amplifier according to the level of data used in modulation.

Description

TECHNICAL FIELD [0001] The present invention relates to a noise suppression apparatus for an injected locked light source, and a WDM-PON system having the noise suppression apparatus and a WDM-PON system having the noise suppression apparatus.

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a noise suppression apparatus for an injected locked light source and a wavelength division multiplexed passive optical network (WDM-PON) system having the same.

In general, the WDM-PON system has been recognized as the ultimate subscriber network to cope with the explosion of network traffic because of its high bandwidth and high security in response to the explosively increasing bandwidth demand in recent years.

As a method of implementing such a WDM-PON, an injection locking type WDM-PON has been proposed in which a wavelength of a non-coherent light source is divided and injected into a light source. This method is attracting attention as a powerful solution of WDM-PON because it has gigabit transmission capability and excellent price efficiency. However, the noise of the output light of the injected light source is greatly influenced by the noise of the injected light, which has a disadvantage that high gigabit transmission is difficult.

In this regard, a method of reducing noise using a nonlinear effect occurring in a semiconductor or an optical fiber has been proposed. However, the method using this nonlinear effect also raises a problem of cost and management cost of a high-power light source because the optical power of a certain level or more is required to make a nonlinear effect.

Accordingly, as a method for efficiently and economically reducing noise while the optical power requirement level is low, it is necessary to separate and receive the injection light, convert the separated optical signal into an electrical signal, A noise suppressing device of a feedforward type for adjusting a driving current for driving a light source is disclosed.

However, such conventional techniques have a problem that the noise increases rather than depending on the data level.

[Patent Document 1] Registration No. 10-1239240 (registered on February 03, 2014)

SUMMARY OF THE INVENTION It is an object of the present invention to provide a noise suppression method and a noise suppression method for an injection locked light source that adjusts an amplifier gain according to a noise level or switches a feedforward path according to a noise level, And a WDM-PON system having the same.

According to an aspect of the present invention, there is provided a noise suppression apparatus for suppressing noise applied to a light source in an optical transmitter operating by receiving injection light, comprising: an optical coupler for separating injection light; A converter for converting a noise of the injection light received from the optical coupler into an electric signal; An inverter unit for inverting a phase of the electric signal converted by the conversion unit; An amplifier for adjusting the size of an output of the inverter; A light source driving unit for providing a driving current for driving the light source from the output to the amplifying unit; An adder for adding the driving current and a modulation current including data to the light source; And a control unit for checking the level of the data and controlling the gain of the amplifying unit.

According to another aspect of the present invention, there is provided a noise suppression apparatus for suppressing noise applied to a reflection-type light source in an optical transmitter operating by receiving injection light, the noise suppression apparatus comprising: An optical coupler for separating the reflected light reflected; A converter for converting a noise of the injection light received from the optical coupler into an electric signal; An inverter unit for inverting a phase of the electric signal converted by the conversion unit; An amplifier for adjusting the size of an output of the inverter; A modulator for modulating input data using an output of the amplifying unit and a signal distributed by the optical coupler; And a control unit for checking the level of the data and controlling the gain of the amplifying unit.

According to another aspect of the present invention, there is provided a noise suppression apparatus for suppressing noise applied to a reflection-type light source in an optical transmitter that operates by receiving injection light, Optocouplers; A converter for converting a noise of the injection light received from the optical coupler into an electric signal; An inverter unit for inverting a phase of the electric signal converted by the conversion unit; An amplifier for adjusting the size of an output of the inverter; A light source driving unit for providing a driving current for driving the light source from the output to the amplifying unit; A light source that reflects an output of the light source driving unit and input light from which noise is removed by the injection light; A modulator for modulating input data using reflected light received from the light source; And a control unit for checking the level of the data and controlling the gain of the amplifying unit.

In one embodiment of the present invention, the control section can control the amplification section to operate with the first gain when the data is at one level.

In one embodiment of the present invention, the control section can control the amplification section to operate with the second gain when the data is at the 0 level.

In one embodiment of the present invention, the first gain may be greater than the second gain.

In one embodiment of the present invention, the optical coupler and the light source may further include a delay unit connected between the optical coupler and the light source to compensate for temporal loss due to the path difference.

In one embodiment of the present invention, the optical signal processing apparatus may further include a delay unit connected between the optical coupler and the modulation unit, for compensating temporal loss due to the path difference.

In order to solve the above-described problems, a wavelength division multiplexing passive optical network (WDM-PON) system having the above noise suppression apparatus can be provided.

According to another aspect of the present invention, there is provided a noise suppression apparatus for suppressing noise applied to a light source in an optical transmitter operating by receiving injection light, comprising: an optical coupler for separating injection light; A converter for converting a noise of the injection light received from the optical coupler into an electric signal; An inverter unit for inverting a phase of the electric signal converted by the conversion unit; An amplifier for adjusting the size of an output of the inverter; A light source driving unit for providing a driving current for driving the light source from the output to the amplifying unit; An adder for adding the driving current and a modulation current including data to the light source; And a switch unit which is turned on and off according to the level of the data.

According to another aspect of the present invention, there is provided a noise suppression apparatus for suppressing noise applied to a reflection-type light source in an optical transmitter operating by receiving injection light, the noise suppression apparatus comprising: An optical coupler for separating the reflected light reflected; A converter for converting a noise of the injection light received from the optical coupler into an electric signal; An inverter unit for inverting a phase of the electric signal converted by the conversion unit; An amplifier for adjusting the size of an output of the inverter; A modulator for modulating input data using an output of the amplifying unit and a signal distributed by the optical coupler; And a switch unit which is turned on and off according to the level of the data.

According to another aspect of the present invention, there is provided a noise suppression apparatus for suppressing noise applied to a reflection-type light source in an optical transmitter that operates by receiving injection light, Optocouplers; A converter for converting a noise of the injection light received from the optical coupler into an electric signal; An inverter unit for inverting a phase of the electric signal converted by the conversion unit; An amplifier for adjusting the size of an output of the inverter; A light source driving unit for providing a driving current for driving the light source from the output to the amplifying unit; A light source that reflects an output of the light source driving unit and input light from which noise is removed by the injection light; A modulator for modulating input data using reflected light received from the light source; And a switch unit which is turned on and off according to the level of the data.

In one embodiment of the present invention, the switch unit can be turned on when the data is at one level, and can be turned off when the data is at zero level.

In one embodiment of the present invention, the gain of the amplifying unit can be optimized and set to the case where the data is one level.

In one embodiment of the present invention, the optical coupler and the light source may further include a delay unit connected between the optical coupler and the light source to compensate for temporal loss due to the path difference.

In one embodiment of the present invention, the optical signal processing apparatus may further include a delay unit connected between the optical coupler and the modulation unit, for compensating temporal loss due to the path difference.

In addition, in order to solve the above-described technical problem, a WDM-PON system including the above noise suppression apparatus can be provided.

According to the present invention as described above, the gain of the amplifying part is adjusted according to the level of the data included in the modulation current, so that noise suppression by the feedforward method can be performed more efficiently.

Further, the present invention has the effect of turning on / off the feedforward path in accordance with the level of data included in the modulation current, thereby more effectively suppressing the noise by the feedforward method.

1 is a block diagram of a noise suppression apparatus of a conventional injection locked light source.
2A shows noise when the noise suppression apparatus of the present invention is not used.
Figs. 2B and 2C show noise at one level and noise at zero level, respectively, when the gain is set to an optimum level for one level of data.
3 is a block diagram of an apparatus for suppressing noise of an injection locked light source according to a first embodiment of the present invention.
4 is a block diagram of an apparatus for suppressing noise of an injection locked light source according to a second embodiment of the present invention.
5 is a block diagram of an apparatus for suppressing noise of an injection locked light source according to a third embodiment of the present invention.
6 is a block diagram of an apparatus for suppressing noise of an injection locked light source according to a fourth embodiment of the present invention.
7 is a block diagram of an embodiment of a WDM-PON system equipped with an apparatus for suppressing noise of an injection-locked light source of the present invention.
8 is a block diagram of another embodiment of a WDM-PON system having a noise suppression apparatus of an injection locked light source of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a noise suppression apparatus of a conventional injection locked light source.

In the conventional noise suppression apparatus, injection light output from the light source 200 for injection and transmitted to the optical transmitter 100 is divided into two parts through the optical coupler 110. A part of the injection light is transmitted to the conversion unit 140, and the conversion unit 140 detects noise of the injection light and converts the noise into an electric signal. The noise converted into the electric signal is converted into a reverse phase by the inverter unit 150, the amplitude is adjusted by the amplification unit 160, and the noise is transmitted to the light source driving unit 170.

The light source driving unit 170 receives the noise that has been converted to the opposite phase, adds the noise to the modulation current and the driving current, and outputs the sum to the light source 130. The light source driving unit 170 adjusts the driving current so that the driving current becomes small when the injected light becomes large due to the intensity noise and becomes large when the injected light becomes small.

Another output of the optical coupler 110 is injected into the light source 130. Since the noise of the light injected into the light source 130 and the noise transmitted from the light source driving unit 170 are in opposite phases to each other, And noise is suppressed.

In such a conventional noise suppression apparatus, the optimized gain of the amplification unit 160 is determined by the following equation.

At this time, when the gain of the amplifier 160 of the feedforward circuit is set to an optimum value, the best noise reduction effect is obtained. Here, P is the optical power injected into the light source 130, and I represents the driving current.

If the gain of the amplification unit 160 is smaller than the optimum value, the noise reduction effect is reduced. If the gain is decreased to 0, no noise reduction effect is obtained. Also, if the gain is larger than the optimal value, the noise reduction effect is rather reduced, and if the gain is continuously increased, the signal of the feedforward circuit cancels the noise, and rather the noise increases.

On the other hand, when data is one level, I is large, and when data is zero level, I is small. Therefore, the 1-level optimization gain is larger than the 0-level optimization gain. However, in the circuit, since the noise of the 1-level data is dominant, the noise elimination mainly targets the 1-level data. In this case, the noise reduction effect of the 0-level data is deteriorated or rather the noise is increased There is a case of discarding.

FIG. 2A shows noise when the noise suppression apparatus of the present invention is not used. FIG. 2B and FIG. 2C show noise at one level and noise at one level Noise is shown as relative noise intensity (RIN) (Fig. 2A) when the feed forward circuit is not used, when the injection power is -15 dBm, when the feed forward circuit is used, the RIN (FIG. 2B) and RIN at the 0 level (FIG. 2C) when a feed forward circuit is used.

As shown in the figure, in the case of using the feedforward circuit, the noise is reduced for the 1-level data as compared with the case where the 1-level data is not used. However, as compared with the case where the feedforward circuit is not used for the 0- , Respectively.

In order to solve such a problem, according to the present invention, the gain of the amplifier part of the feedforward circuit is varied according to the level of the data, or the feedforward circuit is blocked when the level of the data is 0 level, It provides a structure to effectively reduce noise according to level.

First Embodiment

3 is a block diagram of an apparatus for suppressing noise of an injection locked light source according to a first embodiment of the present invention.

As shown in the figure, a noise suppressing apparatus of an embodiment of the present invention is generally provided in a photocoupler 1, and the optical transmitter 1 includes an optical coupler 11, a delay unit 12, A light source 13, a conversion unit 14, an inverter unit 15, an amplification unit 16, a light source driving unit 17, an addition unit 18, and a control unit 19.

The optical transmitter 1 to which the present invention is applied receives light (injection light) to be injected from the light source for injection 2 into the light source 13.

The optical coupler 11 receives the injection light, separates it, and outputs it to the conversion unit 14 and the delay unit 12.

The converting unit 14 converts the noise of the injected light into an electric signal at the output of the optical coupler 11. [ The conversion unit 14 may be, for example, a photo diode.

The inverter unit 15 inverts the phase of the noise converted into the electric signal, and the amplifier unit 16 is connected to the inverter unit 15 to adjust the magnitude of the phase-inverted noise.

The light source driving unit 17 is connected to the amplifying unit 16 and receives the output of the amplifying unit 16 and provides the driving current to the light source 13 using the output.

The adder 18 receives the modulation current including the data, adds it to the drive current of the light source driver 17, and outputs the sum to the light source 13.

The control unit 19 checks the level of the data from the modulation current and controls the amplification unit 16 so that the amplification unit 16 operates with the first gain when the data is one level and the second gain when the data is at the zero level 16). As shown in Equation (1), the gain is proportional to the drive current, so that the first gain is larger than the second gain. That is, the first gain is optimized when the data is one level, and the second gain is optimized and set when the data is at the zero level.

The delay unit 12 can compensate for the temporal loss.

The operation of the noise suppression apparatus of FIG. 3 will now be described.

The injection light output from the injection light source 2 and transmitted to the optical transmitter 1 is distributed by the optical coupler 11. [ And a part of the injection light is transmitted to the conversion section 14. [

The conversion unit 14 detects noise of the injection light and converts the noise into an electric signal. The noise converted into the electrical signal is converted into a reverse phase by the inverter unit 15, the amplitude is adjusted by the amplification unit 16, and the noise is transmitted to the light source driving unit 17.

At this time, the control unit 19 checks the level of the data, and controls the amplifying unit 16 to operate with the first gain when the level is 1 and the second gain when the level is 0. The amplifying unit 16 controls the control unit The output of the inverter unit 15 can be amplified by applying the gain set by the control of the inverter 19.

The light source driver 17 receives the noise that has been converted to the opposite phase, and outputs the driving current. The light source driving unit 17 can adjust the driving current so that the driving current becomes small when the injected light becomes large due to the intensity noise and becomes large when the injected light becomes small.

The adder 18 receives the modulation current including data composed of 0 level and 1 level, and outputs the modulated current to the light source 13 in addition to the drive current.

On the other hand, another output of the optical coupler 11 is injected into the light source 13.

The delay unit 12 delays the injected light output from the optical coupler 11 and supplies the delayed light to the light source 13. The noise of the injected light injected into the light source 13 and the noise transmitted from the light source driving unit 17 are transmitted to each other Since they are in opposite phases, they act in a direction to cancel each other, so that noise can be suppressed.

When the light source 13 is of the reflection type, the output light of the light source 13 whose noise is suppressed becomes the output light of the optical transmitter Tx through the optical coupler 11. On the other hand, in the case where the light source 13 is of the non-reflecting type, it is obvious to those having ordinary skill in the art to which the present invention belongs that the light is outputted without being passed through the optical coupler 11, that is, something to do.

Second Embodiment

4 is a block diagram of an apparatus for suppressing noise of an injection locked light source according to a second embodiment of the present invention.

As shown in the figure, a noise suppression apparatus according to a second embodiment of the present invention is generally provided in an optical transmitter 1, and includes an optical coupler 11, a delay unit 12, a light source 13, A converter section 14, an inverter section 15, an amplification section 16, a light source driving section 17, an adding section 18 and a switch section 20.

The second embodiment of the present invention is different from the first embodiment in that the control unit 19 is omitted and the switch unit 20 is further included and the configuration other than the switch unit 20 is the same as that of the first embodiment.

The switch unit 20 switches the feed forward path (the conversion unit 14 - the inverter unit 15 - the amplification unit 16 - the light source driving unit 17 - the addition unit 18) according to the level of the data. That is, the feedforward path is turned on when the data is at level 1, and the feedforward path is turned off when the data is at level 0. At this time, the gain of the amplifying unit 16 is optimized and set to the case where the data is at one level.

The other components are the same as those described with reference to Fig. 3, and therefore, the description thereof will be omitted.

Third Embodiment

5 is a block diagram of an apparatus for suppressing noise of an injection locked light source according to a third embodiment of the present invention.

As shown in the figure, a noise suppression apparatus according to a third embodiment of the present invention is provided in an optical transmitter 1, and includes first and second broadcasters 21 and 22, a light source 23, An optical coupler 24, a delay unit 25, a modulating unit 26, a converting unit 27, an inverter unit 28 and an amplifying unit 29.

The third embodiment of the present invention shows a configuration using the modulator 26 instead of the case where the modulating current is directly injected into the adder 18 of the first and second embodiments. The functions of the basic components are similar to those of the first and second embodiments, and thus the operation will be described.

The injection light output from the injection light source 2 is input to the optical transmitter 1. [

The injected light input to the optical transmitter 1 passes through the first and second optical circulators 21 and 22 and is input to the light source 23 and reflected by the light source 23 to be incident on the second optical circulator 22 to the optical coupler 24 and distributed. At this time, the light source 23 is a reflection type light source.

The noise of the reflected light distributed by the optical coupler 24 is converted into an electrical signal by the converting unit 27, converted into an opposite phase by the inverter unit 28, and adjusted in size by the amplifying unit 29 And is input to the modulating unit 26.

The reflected light split by the optical coupler 24 is delayed by the delay unit 25 and input to the modulating unit 26. [

Since the noise of the reflected light inputted to the modulating section 26 and the noise inputted from the amplifying section 29 are in opposite phases to each other, they act in a direction of canceling each other to suppress noise, and the modulating section 26 Modulated, and output through the first optical circulator 21.

In the embodiment of the present invention, the first and second optical circulators 21 and 22 have been described as an example of changing the optical path. However, the present invention is not limited to this, and other elements having the same function, such as an optical coupler, .

The first embodiment and the second embodiment of the present invention can be applied to the optical transmitter configured as described above. Therefore, although not shown, a control unit or a switch unit can be included.

That is, the amplification unit 29 can apply the gains individually to the data input to the modulation unit 26 as in the first and second embodiments. At this time, it is possible to control the amplifying unit 29 to operate with the first gain when the level of the data input to the control unit (not shown) and the modulating unit 26 is one level and the second gain when the level of the data is 0 . Alternatively, the gain of the amplifying unit 29 may be optimized and set to the case where the data is one level, and the switch unit (not shown) may turn off the feedforward circuit when the data is at the 0 level. At this time, it may be disposed between the switch unit (not shown), the amplifying unit 29 and the modulating unit 26.

Fourth Embodiment

6 is a block diagram of an apparatus for suppressing noise of an injection locked light source according to a fourth embodiment of the present invention.

As shown in the figure, a noise suppression apparatus according to a fourth embodiment of the present invention includes first and second broadcasters 31 and 32, a modulator 33, an optical coupler 34, a delay unit 35, a light source 36, a conversion unit 37, an inverter unit 38, an amplification unit 39, and a light source driving unit 40.

The operation of the fourth embodiment of the present invention will be described below.

The injection light output from the injection light source 2 is input to the optical transmitter 1. [

The injected light input to the optical coupler 34 via the first and second optical circulators 31 and 32 is split and input to the conversion unit 37 so that the noise of the split injection light is converted into the noise And is converted into an electric signal. The inverter unit 38 converts the signal to an inverted phase, and the amplitude of the signal is adjusted by the amplifying unit 39 and input to the light source driving unit 40. The light source driving unit 40 applies a driving current for driving the light source to the light source 36.

Further, the signal distributed by the optical coupler 34 is input to the light source 36 via the light edge portion 35.

Since the injected light injected into the light source 36 and the noise transmitted from the light source driving unit 40 are in opposite phases to each other, they act in a direction to cancel each other, so that noise can be suppressed.

The reflected light reflected by the reflection type light source 36 is input to the modulation unit 33 by the second optical circulator 32 and the modulation unit 33 can modulate the input data by using the reflected light.

In the embodiment of the present invention, the first and second optical circulators (31 and 32) are exemplified as examples of changing the optical path. However, the present invention is not limited to this, and other elements such as an optical coupler May be used.

The first embodiment and the second embodiment of the present invention can be applied to the optical transmitter 1 configured as described above. Therefore, although not shown, a control unit or a switch unit can be included.

That is, the amplification unit 39 can apply the gains individually to the modulating unit 33 as in the first and second embodiments. At this time, it is possible to control the amplification unit 39 to operate with the first gain when the level of the data input to the control unit (not shown) and the modulation unit 33 is one level and the second gain when the level of the data is zero . Alternatively, the gain of the amplifying unit 39 may be optimized and set to the case where the data is at one level, and the switch unit (not shown) may turn off the feedforward circuit when the data is at the zero level. At this time, it may be disposed between the switch unit (not shown), the amplification unit 39, and the light source driver 40.

7 is a block diagram of an embodiment of a WDM-PON system equipped with an apparatus for suppressing noise of an injection-locked light source of the present invention.

As shown in the figure, a WDM-PON system according to an embodiment of the present invention includes a central office (CO) 3, a remote node (RN) 4, and an optical network unit Unit (ONU) (5).

The CO 3 includes a light source 2 for injection as a base station and the light source 2 for injection includes a light source 21 for injecting a signal for downward and a light source 22 for injecting an upward signal. Further, the light source 2 includes a circulator 23. The circulator 23 is a device having three ports, in which a signal input to the first port is output to the second port and a signal input to the second port is output to the third port. The signal input to the third port is lost.

The CO 3 includes a plurality of optical line terminals (OLT) 31 and a first WDM multiplexer / demultiplexer 32. The OLT 31 comprises an optical transmitter 1 (denoted as 'Tx1', ... 'Txn' in FIG. 4), an optical receiver (Rx1, .. Rxn), and a wavelength And a WDM (Wavelength Division Multiplexer).

The RN 4 may be, for example, a router located in an apartment management room or the like, and includes a second wavelength division multiplexer / demultiplexer 41.

The ONU 5 is a unit provided in each home and includes an optical network terminal (ONT) 51. The ONT 51 may include an optical transmitter 1 and a light receiving end equipped with the noise suppressing apparatus of the present invention, and a WDM as the OLT 31 on the user side.

A signal from the CO 3 to the ONU 5 is a down signal and a signal from the ONU 5 to the CO 3 is an up signal.

The operation of the WDM-PON system according to an embodiment of the present invention will be described. Since the system of FIG. 7 is symmetrically constructed, the downward direction will be described.

The broad spectrum light output from the light source 21 for injecting signals for downstream signals is input to the first port of the circulator 23 and is output to the second port to be output to the RN 40 via a single mode fiber To the second wavelength division multiplexer / demultiplexer 41 of the second wavelength division multiplexer / demultiplexer 41.

The second wavelength division multiplexer / demultiplexer 41 divides the received light into wavelengths of each channel, wherein the noise of the injection light is greatly increased.

Thereafter, the wavelength-divided light is input into the WDM of the ONT 51. [ Generally, the L band (1565 nm to 1625 nm) is used as the downstream signal. The WDM of the ONT 51 transmits L-band light, which differs depending on the wavelength, to the optical transmitter 1 and light of another wavelength band to the optical receiver Rx. Therefore, the light received by the ONT 51 is injected into the optical transmitter 1 to which the present invention is applied.

At this time, the optical transmitter 1 may be applied to the noise suppressing apparatus of the first embodiment of Fig. 3, or the noise suppressing apparatus of the second embodiment of Fig. 4 may be applied.

When the noise suppression device of the first embodiment is applied, the injected light injected into the optical transmitter 1 is distributed by the optical coupler 11, one of which is transmitted to the light source 13, 14 so that the noise of the injected light is converted into an electric signal. The inverter unit 15 inverts the phase of the output of the conversion unit 14 and the amplification unit 16 adjusts the amplitude of the phase-inverted signal.

The light source driving unit 17 receives the noise that has been converted to the opposite phase and outputs the driving current. The adding unit 18 adds the modulation current including the data and the driving current to the light source 13.

The control unit 19 checks the level of the data and controls the amplifying unit 16 to operate with the first gain when the level is 1 and the second gain when the level is 0. The amplifying unit 16 controls the control unit 19, The output of the inverter unit 15 can be adjusted by applying the gain set by the control of FIG.

On the other hand, when the noise suppression apparatus of the second embodiment is applied, the injected light injected into the optical transmitter 1 is distributed by the optical coupler 11, one of which is transmitted to the light source 13, And the noise of the injection light is converted into an electric signal. The inverter unit 15 inverts the phase of the output of the conversion unit 14 and the amplification unit 16 adjusts the amplitude of the phase-inverted signal.

The light source driving unit 17 receives the noise that has been converted to the opposite phase and outputs the driving current. The adding unit 18 adds the modulation current including the data and the driving current to the light source 13.

The switch unit 20 switches the feedforward path according to the level of the data. That is, the feedforward path is turned on when the data is at level 1, and the feedforward path is turned off when the data is at level 0. At this time, the gain of the amplifying unit 16 may be optimized and set when the data is at one level.

In one embodiment of the present invention, the light source 13 operates substantially as an optical amplifier. In the light source, since the drive current and the gain are substantially proportional, the gain is small when the injection light is large, and becomes large when the injection light is small. Therefore, it is possible to flatten the output light after passing through the light source 13.

Thereafter, the noise-suppressed light having passed through the reflection type light source 13 of the optical transmitter 1 is transmitted to the SMF by the second wavelength division multiplexer / demultiplexer 41 via the WDM of the ONT 51 Passed through the two circulators 23, and can be transmitted to the receiver Rx via the first WDM MUX / DEMUX 32.

8 is a block diagram of another embodiment of a WDM-PON system having a noise suppression apparatus of an injection locked light source of the present invention.

The WDM-PON system of FIG. 8 is different from the WDM-PON system of FIG. 7 only in the position of the light source 2, and the principle thereof is the same as that of the WDM-PON system according to the embodiment of FIG.

The third wavelength division multiplexer / demultiplexer 33 divides the light output from the multi-wavelength light source for injection 2 and supplies the divided light to the OTL 31.

The light outputted from the light source 2 for injection is divided by the third wavelength division multiplexer / demultiplexer 33 and injected into the optical transmitter 1 of the OLT 31, Is received by the optical receiver Rx of the ONT 51 via the first wavelength division multiplexer / demultiplexer 32, the SMF, the second wavelength division multiplexer / demultiplexer 41, and the like.

The other detailed description is already described with reference to FIG. 4, so that the description will be omitted.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims. Accordingly, the true scope of the present invention should be determined by the following claims.

1: optical transmitter 2: light source for injection
11: Optocoupler 12: Delay unit
13: Light source 14:
15: inverter section 16: amplifying section
17: light source driving unit 18:
19: control unit 20: switch unit

Claims (18)

A noise suppression apparatus for suppressing noise applied to a light source in an optical transmitter operating by receiving injection light,
An optical coupler for separating the injected light;
A converter for converting a noise of the injection light received from the optical coupler into an electric signal;
An inverter unit for inverting a phase of the electric signal converted by the conversion unit;
An amplifier for adjusting the size of an output of the inverter;
A light source driving unit for providing a driving current for driving the light source from the output to the amplifying unit;
An adder for adding the driving current and a modulation current including data to the light source; And
And a control unit for checking the level of the data to control the gain of the amplifying unit.
A noise suppressing apparatus for suppressing noise applied to a reflection-type light source in an optical transmitter operating by receiving injection light,
An optical coupler for separating reflected light reflected from the reflection type light source;
A converter for converting a noise of the injection light received from the optical coupler into an electric signal;
An inverter unit for inverting a phase of the electric signal converted by the conversion unit;
An amplifier for adjusting the size of an output of the inverter;
A modulator for modulating input data using an output of the amplifying unit and a signal distributed by the optical coupler; And
And a control unit for checking the level of the data to control the gain of the amplifying unit.
A noise suppressing apparatus for suppressing noise applied to a reflection-type light source in an optical transmitter operating by receiving injection light,
An optical coupler for separating the injected light;
A converter for converting a noise of the injection light received from the optical coupler into an electric signal;
An inverter unit for inverting a phase of the electric signal converted by the conversion unit;
An amplifier for adjusting the size of an output of the inverter;
A light source driving unit for providing a driving current for driving the light source from the output to the amplifying unit;
A light source that reflects an output of the light source driving unit and input light from which noise is removed by the injection light;
A modulator for modulating input data using reflected light received from the light source; And
And a control unit for checking the level of the data to control the gain of the amplifying unit.
4. The apparatus according to any one of claims 1 to 3,
And controls the amplification section to operate at a first gain when the data is at one level.
5. The apparatus of claim 4,
And controls the amplifier to operate at the second gain when the data is at the 0 level.
6. The apparatus of claim 5, wherein the first gain is greater than the second gain.
The method according to claim 1 or 3,
And a delay unit connected between the optical coupler and the light source to compensate for temporal loss due to a path difference.
3. The method of claim 2,
And a delay unit coupled between the optical coupler and the modulator to compensate temporal loss due to a path difference.
A wavelength division multiplexing passive optical network (WDM-PON) system having the noise suppression apparatus according to any one of claims 1 to 3.
A noise suppression apparatus for suppressing noise applied to a light source in an optical transmitter operating by receiving injection light,
An optical coupler for separating the injected light;
A converter for converting a noise of the injection light received from the optical coupler into an electric signal;
An inverter unit for inverting a phase of the electric signal converted by the conversion unit;
An amplifier for adjusting the size of an output of the inverter;
A light source driving unit for providing a driving current for driving the light source from the output to the amplifying unit;
An adder for adding the driving current and a modulation current including data to the light source; And
And a switch unit that is turned on and off according to the level of the data.
A noise suppressing apparatus for suppressing noise applied to a reflection-type light source in an optical transmitter operating by receiving injection light,
An optical coupler for separating reflected light reflected from the reflection type light source;
A converter for converting a noise of the injection light received from the optical coupler into an electric signal;
An inverter unit for inverting a phase of the electric signal converted by the conversion unit;
An amplifier for adjusting the size of an output of the inverter;
A modulator for modulating input data using an output of the amplifying unit and a signal distributed by the optical coupler; And
And a switch unit that is turned on and off according to the level of the data.
A noise suppressing apparatus for suppressing noise applied to a reflection-type light source in an optical transmitter operating by receiving injection light,
An optical coupler for separating the injected light;
A converter for converting a noise of the injection light received from the optical coupler into an electric signal;
An inverter unit for inverting a phase of the electric signal converted by the conversion unit;
An amplifier for adjusting the size of an output of the inverter;
A light source driving unit for providing a driving current for driving the light source from the output to the amplifying unit;
A light source that reflects an output of the light source driving unit and input light from which noise is removed by the injection light;
A modulator for modulating input data using reflected light received from the light source; And
And a switch unit that is turned on and off according to the level of the data.
13. The apparatus according to any one of claims 10 to 12,
And when the data is one level, is turned on.
13. The apparatus according to any one of claims 10 to 12,
And is turned off when the data is at the 0 level.
13. The method according to any one of claims 10 to 12,
And when the data is one level, it is optimized and set.
13. The method according to claim 10 or 12,
And a delay unit connected between the optical coupler and the light source to compensate for temporal loss due to a path difference.
12. The method of claim 11,
And a delay unit coupled between the optical coupler and the modulator to compensate temporal loss due to a path difference.
A WDM-PON system having the noise suppression apparatus according to any one of claims 10 to 12.

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