KR102106129B1 - Device for high-density wavelength multiplexing communication using wavelength locking - Google Patents

Abstract

In a wavelength division multiplexing passive optical network, which includes an optical fiber optic termination device (OLT) and an optical subscriber unit (ONU) according to an embodiment of the present invention, The method of adjusting the wavelength includes: a first oscillation wavelength that receives, through the first filter having a Gaussian passband, a first oscillation wavelength optical signal transmitted from the optical path termination device to the first oscillation wavelength by the optical subscriber device. Optical signal receiving step, in the optical path termination device, the first optical power information transmission step of transmitting the first optical power information measuring the optical power of the first oscillation wavelength optical signal to the optical subscriber device, the optical subscriber device , A first optical power information receiving step of receiving the first optical power information, In the optical path termination device, the second optical wavelength of oscillation transmitted from the optical subscriber device to a second oscillation wavelength smaller than the first oscillation wavelength A first oscillation wavelength optical signal receiving step of receiving a signal through the first filter, the optical path termination device transmits second optical power information measuring the optical power of the second oscillation wavelength optical signal to the optical subscriber device A second optical power information transmitting step, a second optical power information receiving step of receiving the second optical power information from the optical subscriber device, and an optical path termination device, wherein the optical subscriber device is larger than the first oscillation wavelength A third oscillation wavelength optical signal receiving step of receiving a third oscillation wavelength optical signal oscillating with a third oscillation wavelength through the first filter, and in the optical path termination device, the optical power of the second oscillation wavelength optical signal is received. A third optical power information transmitting step of transmitting the measured third optical power information to the optical subscriber device, a third optical power information receiving step of receiving the third optical power information in the optical subscriber device, the optical subscriber device In, it may be configured to include the step of changing the oscillation wavelength to compare the first to third optical power information, and to change the first oscillation wavelength according to the result.

Description

High Density Wavelength Multiplexing Communication Device Using Wavelength Locking Function {DEVICE FOR HIGH-DENSITY WAVELENGTH MULTIPLEXING COMMUNICATION USING WAVELENGTH LOCKING}

The present invention relates to a high-density wavelength multiplexed communication device and method using a wavelength lock function.

More specifically, a high-density wavelength multiplexing communication device and method for locking a wavelength using dithering and subcarrier information and generating a high-density wavelength through temperature control without using a prior art wavelength locker will be.

With the development of information technology, there is a demand for an improvement in the transmission capacity of a subscriber network due to the increasing internet and multimedia communication traffic.

As a method of improving the transmission capacity of the subscriber network, a wavelength division multiplexing (WDM-PON)-passive optical network (WDM-PON) is spotlighted.

Wavelength division passive optical network (WDM-PON) is shown in Figures 1a to 1c, the optical line termination device 10 (OLT: Optical Line Terminal), a remote node device 30 (RN: Remote Note) And an optical network unit (ONU). Since the wavelength division passive optical network (WDM-PON) uses different optical wavelengths for each channel, it can be realized through the principle that even if the same optical path is used, each optical signal does not influence each other.

On the other hand, the optical line termination device 10 of the conventional passive optical communication network configured as described above requires various devices such as a MUX, a Demux, and a wavelength locker in order to control and lock the wavelength. It was an element. More specifically, the mux and demux are essential components used in the process of synthesizing or separating optical signals transmitted and received.

In addition, in a conventional passive optical communication network such as Korean Patent Registration No. 10-0910940, the optical path termination device is equipped with a wavelength locker, and generates a wavelength control signal from the result of comparing the signal strengths of the uplink signal and the wavelength locker and downlinks them. The method of adjusting the wavelength in the optical subscriber device by transmitting it as an optical signal was used. However, this prior art has a problem in that the optical line terminal 10 has a complicated optical path termination device 10 as well as the above-described mux and demux.

In addition, in the method of transmitting the wavelength control signal as a downlink signal, since the wavelength control signal is simply a subcarrier transmission method, a region in contact with the optical signal for data communication occurs, so that the optical subscriber device 20 adjusts the wavelength from the downlink signal. In detecting the signal, there is a problem that the reception sensitivity of the optical signal is lowered.

In addition, the conventional optical line termination device 10 was used as an expensive wavelength locker including Etalon, a comparator, and the like as shown in FIG. 1C.

Accordingly, the present invention is to provide an optical communication method and apparatus that simplifies various filters such as the MUX and DEMUX, enables wavelength adjustment without a wavelength locker, and does not degrade the reception sensitivity of an optical signal.

On the other hand, in a conventional optical communication network, as a wavelength of light used in optical communication, C-band and L-band regions having relatively large color dispersion but low optical loss are used, and corresponding optical communication devices have been developed. However, the C-band and L-band bands are regions where color dispersion is large. When color dispersion is present, signals of various wavelengths are included in one optical signal, and the transmission speed of light is different for each wavelength. There was a problem in that accurate signal transmission was not possible due to the phenomenon of spreading. Therefore, the conventional optical communication equipment and networks using C-band and L-band have been disadvantageous for long-distance signal transmission. In addition, the higher the speed of the signal, the greater the effect of color dispersion, so the higher the speed of the signal, the more difficult to transmit over a long distance. This phenomenon was especially weighted in the case of DWDM where the wavelength spacing should be kept below 100 Ghz (about 0.8 nm). In such an optical communication network using C-band and L-band, in the laser generator that generates light, when using the direct modulation method, there is a problem that the color dispersion increases in the process of modulating the laser. Although a small number of external modulation methods were used, the cost was very high due to the adoption of an external modulation method and an expensive wavelength locker for DWDM. For this reason, C-band and L-band communication are mainly used for long-distance communication in the Back Bone or Metro area on the network, and there is a problem that the price of parts is expensive to use in the Access area, which is currently increasing in capacity.

Korean Registered Patent Publication 10-0910940

The present invention is to provide a wavelength division multiplexing passive optical network capable of simplifying wavelength control and a method for adjusting the wavelength of an optical signal in the optical communication network as compared to the conventional method. It is also an object of the present invention to provide a method for adjusting a wavelength without a wavelength locker, and to provide an optical communication network and a communication method with improved reception sensitivity of a signal for controlling a wavelength.

In addition, it is an object of the present invention to configure a communication network at a low cost by enabling wavelength control only by adjusting the temperature of the laser without using a separate wavelength adjusting element such as an external resonator.

In addition, it is an object of the present invention to implement high-density wavelength multiplexing at low cost by using light of O, E, and S bands in which high-density wavelength multiplexing technology (DWDM) has not been developed using a low-cost direct modulation laser.

In a wavelength division multiplexing passive optical network, which includes an optical fiber optic termination device (OLT) and an optical subscriber unit (ONU) according to an embodiment of the present invention, The method of adjusting the wavelength includes: a first oscillation wavelength that receives, through the first filter having a Gaussian passband, a first oscillation wavelength optical signal transmitted from the optical path termination device to the first oscillation wavelength by the optical subscriber device. Optical signal receiving step, in the optical path termination device, the first optical power information transmission step of transmitting the first optical power information measuring the optical power of the first oscillation wavelength optical signal to the optical subscriber device, the optical subscriber device , A first optical power information receiving step of receiving the first optical power information, In the optical path terminating device, the second optical wavelength oscillation transmitted from the optical subscriber device to a second oscillation wavelength smaller than the first oscillation wavelength A first oscillation wavelength optical signal receiving step of receiving a signal through the first filter, the optical path termination device transmits second optical power information measuring the optical power of the second oscillation wavelength optical signal to the optical subscriber device A second optical power information transmitting step, the second optical power information receiving step of receiving the second optical power information from the optical subscriber device, and the optical path termination device, wherein the optical subscriber device is larger than the first oscillation wavelength A third oscillation wavelength optical signal receiving step of receiving a third oscillation wavelength optical signal oscillating with a third oscillation wavelength through the first filter, and in the optical path termination device, the optical power of the second oscillation wavelength optical signal is received. A third optical power information transmitting step of transmitting the measured third optical power information to the optical subscriber device, a third optical power information receiving step of receiving the third optical power information in the optical subscriber device, the optical subscriber device In, it may be configured to include the step of changing the oscillation wavelength to compare the first to third optical power information, and to change the first oscillation wavelength according to the result.

On the other hand, the optical subscriber device is configured to include a laser oscillation module coupled with a TEC (Thermo-Electric Cooler), generates an optical signal to the laser oscillation module, the oscillation wavelength change step, the first optical power information In the largest case, the temperature of the TEC (Thermo-Electric Cooler) element is adjusted so that the wavelength of the laser oscillated from the laser oscillation module becomes the first oscillation wavelength, and when the third optical power information is largest, oscillation occurs in the laser oscillation module Adjust the temperature of the TEC (Thermo-Electric Cooler) element so that the wavelength of the laser becomes the third oscillation wavelength, and when the second optical power information is the largest, the wavelength of the laser oscillated by the laser oscillation module is the first 2 It is possible to control the temperature of the TEC (Thermo-Electric Cooler) device to be the oscillation wavelength.

On the other hand, each of the first optical power information transmitting step, the second optical power information transmitting step and the third optical power information transmitting step, each of the first to third optical power information from the optical path termination device to the optical subscriber device Frequency modulating the optical power information to frequency modulate the subcarrier of a low frequency with a carrier modulating the transmitted communication data, generating a demodulated optical signal synthesizing the subcarrier with the carrier, and performing demodulation to transmit the modulated optical signal It may be configured to include an optical signal transmission step.

Meanwhile, each of the first optical power information receiving step, the second optical power information receiving step, and the third optical power information receiving step separates the subcarrier signal by passing the demodulated optical signal through a low-pass filter, and separate subcarriers. The signal can be demodulated to obtain optical power information.

Meanwhile, in the frequency modulation step of the optical power information, the modulation frequency for at least one of the logic 1 or logic 0 of the digital optical power information that converts the optical power information to digital is a baud rate of the digital optical power information (baud- rate).

In an optical communication method according to an embodiment of the present invention, at least one signal formed to attenuate a signal of a frequency deviating from the center frequency by using a predetermined wavelength as a center frequency between the first optical signal transmission and reception module and the second optical signal transmission and reception module. In an optical network that performs data communication through a filter, the first optical signal transmission / reception module generates (a) a first upward optical signal having a predetermined first wavelength and transmits it to the second optical signal transmission / reception module. Step, (b) generating and transmitting first to third uplink optical signals having a first wavelength, a second wavelength smaller than the first wavelength, and a third wavelength larger than the first wavelength, respectively, to the second optical signal transmission / reception module. Step, (c) in the second optical signal transmission / reception module, detecting power of the first to third optical signals through the filter and detecting optical power information to digitalize the first to third optical powers of the power information. Step, sub-carrier modulation step of sub-carrier modulating the detected optical power information, transmitting the first to third downlink optical signal including the sub-carrier modulated signal, (d) in the first optical signal transmission and reception module, the first The optical power information demodulating step of separating the subcarriers included in the first to third downlink optical signals and demodulating the information of the first to third optical powers, comparing the optical power information of the demodulated first to third optical powers, If the first optical power information is the largest, the second optical power information is the largest without changing the first wavelength, the first wavelength is changed to the second wavelength and the third optical power information is the largest, the Steps (a) to (d) may be repeated by changing the first wavelength to the third wavelength.

The optical communication network according to an embodiment of the present invention includes an optical fiber termination device, an optical subscriber device, and at least one periodic repetitive optical wavelength filter (Cyclic AWG), wherein the optical fiber termination device is transmitted from the optical subscriber device. An optical power detector for detecting the optical power of the received optical signal, and generating a subcarrier signal based on the detected optical power information It comprises a subcarrier signal generating unit, a downlink optical signal generating unit for generating a downlink optical signal including the subcarrier signal, a downlink optical signal transmitting unit for transmitting the downlink optical signal to the subscriber end device, the optical subscriber device Is, a wavelength-adjustable upward optical signal generator for generating an upward optical signal of a predetermined wavelength to be transmitted to the optical path termination device, an upward optical signal transmission unit for transmitting the upward optical signal to the optical path termination equivalent, and from the optical path termination device A downlink optical signal receiver for receiving a downlink optical signal including transmitted power information, a low pass filter for separating a subcarrier signal from the received downlink optical signal, and the uplink optical signal generator based on information on the subcarrier signal It comprises a wavelength adjusting signal generating unit for generating a signal for adjusting the wavelength of the uplink optical signal generated by the, the adjustable wavelength uplink signal generation unit, a light generating laser and a TEC (Thermo-Electronic Cooler) device coupled thereto By being configured to include, it is possible to generate an uplink optical signal of the adjusted wavelength through the temperature control of the TEC device under the control of the wavelength control signal generator.

An optical transceiver according to an embodiment of the present invention, an optical signal generator for generating a transmitted optical signal, an optical signal transmission unit for transmitting the generated transmitted optical signal to an external device, information of the transmitted optical signal received from the external device Including an optical signal receiving unit for receiving a received optical signal containing a sub-carrier signal containing, a received optical signal analysis unit for obtaining and analyzing information of the transmitted optical signal received from the external device from the received optical signal; including It is configured, and the wavelength of the transmitted optical signal generated by the optical generator may be changed according to the control signal of the received optical signal analyzer.

The optical signal generator may include a laser diode and a TEC device provided adjacent to the laser diode to control the temperature of the laser diode.

The laser diode may be configured to generate optical signals of different wavelengths according to the amount of heat generated by the TEC device.

In the received optical signal analysis unit, information of the transmitted optical signal received from the external device from the received optical signal is optical power information of the transmitted optical signal received from the external device, and the received optical signal analysis unit comprises: The first transmitted optical signal transmitted as an optical signal having one wavelength is the first optical power information, which is optical power information received from an external device, and the second transmitted optical signal transmitted as an optical signal having a second wavelength smaller than the first wavelength. Is the third optical power information received from the external device, the third optical signal transmitted from the external device is the second optical power information received from the external device, and the third optical signal transmitted by the optical signal having the third wavelength greater than the first wavelength. By comparing information, the control signal is output to the optical generator to generate a transmission optical signal at a first wavelength when the first wavelength is largest, and to generate a transmission optical signal at a second wavelength when the second wavelength is largest. A control signal may be output to the optical generator, and when the third wavelength is largest, a control signal may be output to the optical generator to generate a transmitted optical signal at a third wavelength.

In the received optical signal analysis unit, information of the transmitted optical signal received from the external device from the received optical signal is optical power information of the transmitted optical signal received from the external device, and the received optical signal analysis unit comprises: The first transmitted optical signal transmitted as an optical signal having a wavelength is the first optical power information received from an external device, and the second transmitted optical signal transmitted as an optical signal having a second wavelength smaller than the first wavelength. The second optical power information, which is the optical power information received from the external device, and the third optical power information, which is the optical power information received from the external device, the third transmission optical signal transmitted as an optical signal having a third wavelength greater than the first wavelength By comparing each, the control signal is output to the optical signal generator to generate a transmission optical signal at a first wavelength when the first wavelength is largest, and when the second wavelength is largest, at a wavelength smaller than a first wavelength by a predetermined value A control signal is output to the optical signal generator to generate a transmitted optical signal, and when the third wavelength is largest, a control signal is output to the optical signal generator to generate a transmitted optical signal with a wavelength larger than a first wavelength by a predetermined value. Can be.

The optical signal generator may generate an optical signal having a wavelength belonging to any one of the O-band region (1260 to 1360 nm), E-band region (1361 to 1460 nm), and S-band region (1461 to 1530 nm). Can be.

The wavelength division passive optical network according to an embodiment of the present invention, an optical path termination device for transmitting a downlink optical signal multiplexed with at least one optical subscriber device, at least one optical subscriber for transmitting an upward optical signal to the optical path termination device Device, a first cyclic repeatable optical wavelength filter (Cyclic AWG) for transmitting the downlink optical signal to the at least one optical subscriber device, and a second main-based optical wavelength filter (Cyclic AWG) for transmitting the upward optical signal to the optical fiber termination device ), And the optical subscriber device may include the optical transceiver of claim 12.

The optical path termination device includes: an optical power detector for detecting the optical power of the upward optical signal, a subcarrier modulator for modulating the optical power information of the detected upward optical signal into a very low frequency subcarrier, and the downward light including the subcarrier It may be configured to include a downlink signal generator for generating a signal.

The subcarrier modulating unit may match the modulation frequency for at least one of logic 1 or logic 0 of the digital optical power information that converts the optical power information to digital to match the baud rate of the digital optical power information. Can be.

Using the above-described means, the present invention has an effect of providing an optical network and a wavelength control method capable of adjusting the wavelength without a wavelength locker.

In addition, the present invention enables the wavelength adjustment without an expensive wavelength locker by carrying a wavelength control signal on the subcarrier, and transmits the wavelength control signal on an ultra-low frequency subcarrier that minimizes interference with communication data, thereby increasing reception sensitivity. Enhancement Saki has an effect.

In addition, the optical communication network of the present invention is capable of accommodating high-speed signals using light in the O, E, and S bands with little color dispersion, and has low color dispersion, so long-range of high-speed signals using a direct modulation type laser. Enable transmission. For example, when applying the present invention, it is possible to transmit a 10Gbps signal to 20Km.

1A and 1B are diagrams illustrating a wavelength division passive optical network according to an embodiment of the present invention.
1C is a view showing a conventional optical transceiver.
2 is a block diagram of an optical communication network according to an embodiment of the present invention.
3 is a view showing one OLT transceiver and ONU transceiver according to an embodiment of the present invention.
4A to 4D are diagrams illustrating an embodiment of a subcarrier modulator according to an embodiment of the present invention.
5 is a view showing a laser generator according to an embodiment of the present invention.
6 is a view showing a wavelength shift according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains may easily practice. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. In addition, in order to clearly describe the present invention in the drawings, parts irrelevant to the description are omitted, and like reference numerals are attached to similar parts throughout the specification.

Terms including ordinal numbers such as first and second may be used to describe various components, but the components are not limited by the terms. The terms are used only for the purpose of distinguishing one component from other components. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. Terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise.

Throughout the specification, when a part is “connected” to another part, this includes not only “directly connected” but also “electrically connected” with another element in between. . Also, when a part “includes” a certain component, it means that it may further include other components, not to exclude other components, unless otherwise stated. The term “~ (steps)” or “steps of” as used in the present specification does not mean “steps for”.

The terminology used in the present invention has been selected, while considering the functions in the present invention, general terms that are currently widely used are selected, but this may vary according to the intention or precedent of a person skilled in the art or the appearance of a new technology. In addition, in certain cases, some terms are arbitrarily selected by the applicant, and in this case, their meanings will be described in detail in the description of the applicable invention. Therefore, the terms used in the present invention should be defined based on the meanings of the terms and the contents of the present invention, not simply the names of the terms.

1. Optical communication network according to an embodiment of the present invention

2 is a block diagram of an optical communication network according to an embodiment of the present invention.

The optical communication network of the present invention comprises an optical line termination device 100 (OLT: Optical Line Terminal) and an optical subscriber device 200 (ONU: Optical Network Unit; subscriber line termination device). The 100 transmits a downward light signal to the optical subscriber device 200, and receives an upward light signal transmitted by the optical subscriber device 200.

The optical fiber termination device 100 may wavelength-multiplex one or more channel signals and transmit them through one optical line, and the remote node 300 (RN: Remote) demultiplexes them to multiplex one or more channel signals. Distribute to subscriber devices. Such multiplexing / demultiplexing is constructed using MUX and DEMUX in the prior art, but may be implemented using filters 401 and 402 as shown in FIG. 2 in the present invention.

2A is a simplified diagram of the embodiment represented by FIG. 2B.

1.1. Composition of optical fiber termination device

The optical fiber termination device 100 (OLT) of the present invention may be configured to include one or more OLT transceivers 100-1 forming a plurality of communication channels and one periodic repeating optical wavelength filter 401 (Cyclic AWG). . Multiplexing / demultiplexing can be implemented by using the first Cyclic AWG 401 instead of the MUX and DEMUX used in the conventional WDM (Wavelength Division Multiplexing) method.

One OLT transceiver 100-1 constituting channel # 1 (CH # 1) may have a configuration as shown in FIG. 3, and lambda 1 is a wavelength of a downlink optical signal, and lambda 1 'is upwardly illuminated. Can be used as the wavelength of the signal.

The OLT transceiver 100-1 of the present invention receives an uplink optical signal (lambda 1 '), and may include an optical power detector 110 that detects the optical power from the received uplink optical signal. A signal processor 1 120 for generating information corresponding to the optical power from the detected optical power may be further provided, and a modulator 130 for modulating this to generate a subcarrier is provided. The subcarrier can be generated by frequency modulation, wherein the modulator is an FSK modulator.

The modulator of FIG. 4A modulates according to a conventional FSK modulation method, and the modulator of FIG. 4B shows an embodiment that follows a method of ultra low frequency frequency modulation.

In a general frequency modulation method, for example, as shown in FIG. 4A, when the intermediate frequency is set to f0 and the frequency change values for the logic of digital data are set to f1 and f2, respectively, the frequency of the signal after frequency modulation is f0. It will have + f1 to f0 + f2.

In this case, as shown in FIG. 4C, a region overlapping with the digital communication signal may be generated, resulting in poor signal sensitivity.

Therefore, in another embodiment of the present invention, a new type of ultra-low frequency frequency modulation is performed. As shown in FIGS. 4B and 4D, the ultra-low frequency frequency modulation of the present invention matches the frequency of a carrier signal modulated with at least one of a baud rate of digital data and a logic 1 or 0 of digital data. For example, when the baud rate of modulating digital data is 1 KBps, the modulation frequency for logic 0 is set to 1 KHz to match the baud rate, and the modulation frequency for logic 1 is set to 2 KHz.

As shown in FIG. 4B, such an ultra-low-frequency modulation can be easily constructed by using a 2XN Hz oscillator oscillating two times when the baud rate is N bps and a clock divider dividing it twice. Since the intermediate frequency is not used, it can be implemented with a much simpler circuit than the normal FSK modulation using VCO, etc., and when transmitting together with the main digital communication signal as shown in FIG. 4C, the main digital communication signal exists in a very weak band. Therefore, when demodulating it, it is possible to minimize interference caused by digital communication signals.

1.2. Configuration of Remote Node (RN)

The remote node 300 of the present invention may be configured to include a second periodic optical wavelength filter 402 (Cyclic AWG) that multiplexes wavelengths and demultiplexes a downlink optical signal transmitted through an optical path. Each of the demultiplexed optical signals can be transmitted to a plurality of optical subscriber devices as shown in FIG. 2, and the upward optical signals from the multiple optical subscriber devices are multiplexed through the second Cyclic AWG 402 to transmit the optical path. It is demultiplexed through the first Cyclic AWG 401 of the optical fiber termination device, and is input to the OLT transceiver of each channel.

1.3. Composition of optical subscriber device (ONU)

The optical subscriber device 200 of the present invention includes an ONU transceiver 210 as shown in FIG. 3. The ONU transceiver 210 of the present invention receives a downlink signal having a wavelength lambda 1, and includes a low pass filter 211 for detecting a subcarrier signal included in the downlink signal, and a subcarrier demodulating data from the subcarrier signal And a demodulator 212. The subcarrier demodulator 212 may be an FSK demodulator, and includes a signal processor 2 213 that generates a wavelength control signal therefrom.

The ONU transceiver 210 of the present invention may further include a wavelength controller 214 for adjusting the wavelength of the upstream optical signal generated by the all-optical converter 215 by the wavelength control signal generated by the signal processor 2 212. have.

The wavelength controller 214 and the all-optical converter 215 of FIG. 3 constituting the ONU transceiver 210 of the present invention form a grating filter 510 (Bragg Grating) that periodically changes in refractive index as shown in FIG. 5A). It may be composed of a laser generator 500 in which a heater 530 is coupled to a polymer wave guide 520 (Polymer Wavegude). If a temperature change is applied to the grating filter 510 through the heater, the spacing between the gratings is changed. It is possible to control the wavelength of light generated by the laser generator 500 on the principle that the reflected wavelength is changed.

Meanwhile, the conventional optical transmitter illustrated in FIG. 1C compares a signal that passes through Etalon with a signal that does not, and determines a shift in wavelength, and uses a temperature stabilizer to stabilize the wavelength. However, such a conventional technique requires an expensive wavelength locker including Etalon, whereas the optical transmitter of the present invention only uses the wavelength information analyzer 610 and the temperature control circuit 620 as shown in FIG. 5B. The wavelength of light generated by controlling the temperature of the LD 630 is controlled by using the TEC element 640 attached adjacent to the LD 630. Here, the wavelength information analyzer 610 and the TEC device 640 correspond to the signal processor 2 213 and the wavelength controller 214 of the ONU transceiver 210 in FIG. 3. The laser diode 630 (LD (laser oscillation module)) of the present invention generates optical signals of different wavelengths according to the amount of heat generated by the TEC device 640.

By adopting the TEC device 640 as described above, the optical transmission unit of the present invention can implement DWDM using an O / E / S band region with little color dispersion, and can adopt a direct modulation method that is inexpensive. That is, the optical transmission unit including the present LD 630 (optical signal generator) is one of the O-band region (1260 ~ 1360nm), E-band region (1361 ~ 1460nm), S-band region (1461 ~ 1530nm) It generates an optical signal having a wavelength belonging to the region of.

Optical subscriber device 200 of the present invention, an optical signal generator for generating a transmitted optical signal, an optical signal transmission unit for transmitting the generated transmitted optical signal to an external device, information of the transmitted optical signal received from the external device It may be configured to include an optical signal receiving unit for receiving and receiving the received optical signal including the sub-carrier signal, a received optical signal analysis unit for obtaining and analyzing information of the transmitted optical signal received from the external device from the received optical signal. The wavelength of the transmitted optical signal generated by the optical generator may be changed according to the control signal of the received optical signal analyzer. At this time, the received optical signal analysis unit corresponds to the wavelength information analyzer 610 of FIG. 5B and the signal processor 2 213 of FIG. 3.

2. Wavelength multiplexing communication method and wavelength control method by the optical communication network of the present invention

In performing the wavelength multiplexing communication in the optical communication network of the present invention described above, the downlink signal is transmitted to the lambda 1 and the uplink signal from the optical subscriber device of the corresponding channel is transmitted to the lambda 1 ', which is the lambda 1 Uplink optical signal should be transmitted at a fixed wavelength of '.

However, due to environmental factors such as aging and temperature of the equipment, the wavelength lambda 1 'of the upward optical signal may not be fixed and shifted. In the present invention, the wavelength lambda 1' of the upward optical signal may not be fixed. Provides a method for detecting a case where a shift has occurred and automatically adjusting the shift from the shifted wavelength to the wavelength lambda 1 'again.

The present invention can be used not only in the case of adjusting the return when the wavelength is shifted as described above, but also in the case of setting the initial designated wavelength when an upward light signal needs to be generated at a designated wavelength.

2.1. Fine-tuning wavelength transmission of upward light signal

First, the optical subscriber device generates a first oscillation wavelength upward light signal having a first oscillation wavelength with a wavelength-adjustable laser of the optical subscriber device and transmits it to the optical path termination device.

The optical subscriber device generates a second wavelength smaller than the first wavelength (or reference wavelength) that is currently generated and transmitted and a third wavelength larger than the first wavelength, and transmits them as an upward optical signal. In this way, fine-tuning and transmitting from the first wavelength to a larger or smaller wavelength may be sequentially transmitted by setting a predetermined period.

The fine adjustment wavelength (second wavelength and third wavelength) may be performed by adjusting the temperature of the grating filter through temperature control of the heater coupled to the laser generator through the wavelength controller of the optical subscriber device. In addition, when a laser equipped with a TEC device is used, the temperature of the TEC device is adjusted to generate light having a finely adjusted wavelength.

2-2. Detecting optical power of an upward optical signal and transmitting it as a downward optical signal

(1) Detection of received light power

The optical path terminating device, which has received the upward optical signals having the first to third wavelengths, respectively detects these optical powers in the optical power detector. The uplink optical signal may be received through a predetermined filter, and the filter may be composed of a cyclic repeatable optical wavelength filter (Cyclic AWG), and may have a Gaussian pass band.

(2) Transmission of optical power information

The detected optical power is generated by the signal processor as optical power information, and is modulated by a subcarrier modulator (ex. FSK modulator). As described above, the subcarrier modulation may use a method in which a baud rate and a modulation frequency signal are matched to at least one digital logic signal of general FSK or optical power information. The subcarrier uses a low frequency of a different frequency from the carrier that modulates communication data.

The modulated subcarrier signal is double-modulated with communication data to be transmitted (data tx) to generate a downlink signal with a wavelength of lambda 1 and transmit it to the optical subscriber device.

That is, the downlink optical signal can be transmitted using the transmission data signal and the optical power information of the uplink optical signal as a subcarrier signal. The downlink optical signal is transmitted by including the uplink optical signal of the reference wavelength (first wavelength) and the optical power information of the uplink optical signal transmitted through the second and third wavelengths. At this time, if necessary, the optical power information may be transmitted as a subcarrier signal separately from the communication data signal.

At this time, as shown in FIG. 4C, the frequency of the communication signal included in the received downlink signal is widely distributed from the low frequency domain to the high frequency domain, and the energy present in the low frequency domain is transmitted from the OLT transceiver to the subcarrier. It acts as noise in the transmission region of the transmitting subcarrier. However, as shown in FIG. 4C, when an ultra-low frequency modulation is used to match one subcarrier frequency in the digital data logic of the optical power information with the baud rate of the digital data of the optical power information, the optical subscriber device receives it. This has the advantage of minimizing signal interference.

2-3. Receiving the downlink optical signal and adjusting the wavelength of the uplink optical signal

The optical subscriber device receiving the downlink signal containing the optical power information separates the subcarrier signal included in the downlink signal using a low-pass filter, demodulates the subcarrier signal, and then uplinks the first to third wavelength signals Separately, the received optical power information from the optical fiber termination device is obtained.

Referring to FIG. 6, the upward optical signal is received by the optical path termination device through the first and / or second cyclic repeatable optical wavelength filter (Cyclic AWG), and the cyclic repeated optical wavelength filter is maximum in the central wavelength region as shown in the figure. Since it has a gain and has an attenuation effect in its periphery, when an upstream light signal having first to third wavelengths passes through one filter region of a periodic repeating optical wavelength filter set with lambda 1 'as the center wavelength for each channel, respectively. The received optical power at the optical fiber termination device for the upward optical signal of has different values.

(1) When there is no wavelength shift

In other words, as shown in FIG. 6, the pass signal of the known repetition type optical wavelength filter according to the wavelength change is that when the reference wavelength (center wavelength 2) is not shifted from lambda 1 '(FIG. 6 c), the reference wavelength is centered through the filter. As the wavelength matches, the power of the received optical signal of the second wavelength adjusted shorter and the third wavelength adjusted longer is measured weaker. In this case, the optical subscriber device receiving the optical power information determines that there is no shift in the lambda 1 'wavelength that should be originally transmitted to the reference wavelength of the transmitted optical signal and does not change the wavelength. In this case, the temperature of the grating filter of the wavelength-adjustable laser of the present invention is maintained. In addition, when using a laser equipped with a TEC device, the temperature of the TEC device is maintained or controlled to generate a first wavelength.

(2) If there is a short wavelength shift

However, when the optical power information of the second wavelength is larger than the optical power information of the first wavelength as shown in FIG. 6A, the first wavelength (reference 2) in the reference wavelength is shifted from the center of the filter to the left. Will recognize. That is, in this case, since a short wavelength shift has occurred in the transmission wavelength, the reference wavelength is increased to move to the right or the reference wavelength (first wavelength) is adjusted to be the third wavelength (reference numeral 3). In this case, in the next uplink optical signal transmission period, the uplink optical signal is transmitted with the third wavelength being larger than the adjusted first wavelength, and this process is performed when the reference wavelength (first wavelength) optical power information becomes maximum. It continues until.

In the case of short wavelength shift, the wavelength controller of the optical subscriber device generates a signal to increase the wavelength and controls the heater to adjust the temperature of the lattice filter to generate an extended wavelength than the reference wavelength. In addition, when using a laser equipped with a TEC device, the temperature of the TEC device is adjusted to generate an increased wavelength than the reference wavelength.

(3) If there is a long wavelength shift

As shown in FIG. 6B, when the reference wavelength is shifted to a longer wavelength than lambda 1 'and transmitted, it is measured that the optical power of the second wavelength upward optical signal (drawing code 1) is the maximum when receiving optical power information. In this case, it is judged that the reference wavelength is shifted to a longer wavelength than the center pass wavelength of the filter, and the reference wavelength (first wavelength) is moved to the left or the reference wavelength (first wavelength) is adjusted to be changed to the second wavelength (drawing code 1). In this case, in the next uplink optical signal transmission period, the uplink optical signal is transmitted by setting the second wavelength to a wavelength smaller than the newly adjusted first wavelength. In this process, the optical power information of the reference wavelength (the first wavelength) is maximized. It continues until.

In the case of long wavelength shift, the wavelength controller of the optical subscriber device generates a signal that reduces the wavelength, and controls the heater to adjust the temperature of the grating filter to produce a wavelength shorter than the reference wavelength. In addition, when using a laser equipped with a TEC device, the temperature of the TEC device is adjusted to generate a wavelength that is shorter than the reference wavelength.

The wavelength of the optical signal generated for the transmission of the upward optical signal from the optical subscriber device through the wavelength control method of the upward optical signal according to the wavelength shift of (1) to (3) is longer than the desired wavelength lambda 1 ' Alternatively, when shifting to a short wavelength, it may be adjusted to return to the wavelength lambda 1 'again.

The wavelength adjustment procedure may be performed at predetermined periodic intervals, when the external environment changes, such as a sudden temperature change, or continuously performed to monitor the wavelength shift and adjust the wavelength when the shift occurs.

Using the present invention, the wavelength of light transmitted by a predetermined optical transceiver can be adjusted very easily and easily, or can be adjusted to transmit light of a certain wavelength, and furthermore, the light of O, E, and S bands with little color dispersion can be used. It has the effect of reducing the cost by allowing the high-speed signal to be accommodated and allowing the long-distance transmission of the high-speed signal using a laser of a direct modulation method due to low color dispersion.

The terms up / down in the uplink and downlink signals described in the present invention are for distinguishing directionality in two devices, and the optical transceiver in one device must transmit or receive only the uplink or downlink signals. It will be apparent to those skilled in the art that the present invention can be used to both transmit and receive an uplink optical signal and / or a downlink optical signal using the optical transceiver of the present invention.

100: optical fiber termination device (OLT)
200: optical subscriber device (ONU)
300: Remote node (RN)
500: laser generator

Claims (16)

In a wavelength division multiplexing passive optical network comprising an optical fiber termination device (OLT) and an optical subscriber unit (ONU), in a method for adjusting the wavelength of a transmitted optical signal in an optical subscriber device ,
In the optical path termination device, the first oscillation wavelength receives the first oscillation wavelength optical signal transmitted by oscillation with the first oscillation wavelength, which is the transmission wavelength currently set from the optical subscriber device, through a first filter having a Gaussian passband. An optical signal receiving step;
A first optical power information transmitting step of transmitting, at the optical path termination device, first optical power information measuring the optical power of the first oscillation wavelength optical signal to the optical subscriber device;
A first optical power information receiving step of receiving the first optical power information from the optical subscriber device;
In the optical path termination device, a second oscillation wavelength optical signal receiving step of receiving a second oscillation wavelength optical signal transmitted from the optical subscriber device to a second oscillation wavelength smaller than the first oscillation wavelength through the first filter. ;
A second optical power information transmitting step of transmitting, in the optical path termination device, second optical power information measuring the optical power of the second oscillation wavelength optical signal to the optical subscriber device;
A second optical power information receiving step of receiving the second optical power information from the optical subscriber device;
In the optical path termination device, a third oscillation wavelength optical signal receiving step of receiving a third oscillation wavelength optical signal transmitted from the optical subscriber device to a third oscillation wavelength larger than the first oscillation wavelength through the first filter. ;
A third optical power information transmitting step of transmitting, at the optical path termination device, third optical power information measuring the optical power of the second oscillation wavelength optical signal to the optical subscriber device;
A third optical power information receiving step of receiving the third optical power information from the optical subscriber device;
An oscillation wavelength changing step of comparing the first to third optical power information in the optical subscriber device and changing the first oscillation wavelength according to the result;
It comprises,
The oscillation wavelength change step,
When the first optical power information among the first to third optical power information received by the optical subscriber device is the largest, it is determined that there is no wavelength shift, and the wavelength of the laser oscillated by the laser oscillation module is maintained by the first oscillation wavelength. Maintain the temperature of the TEC (Thermo-Electric Cooler) element,
If the third optical power information is the largest among the first to third optical power information received by the optical subscriber device, it is determined that there is a short wavelength shift, and the first oscillation wavelength generated by the laser oscillation module is the third oscillation. Adjust the temperature of the TEC (Thermo-Electric Cooler) device to be a wavelength,
When the second optical power information is the largest among the first to third optical power information received by the optical subscriber device, it is determined that there is a long wavelength shift, and the first oscillation wavelength generated by the laser oscillation module is the second. A method of adjusting the wavelength of a transmitted optical signal that adjusts the temperature of the TEC (Thermo-Electric Cooler) element to be an oscillation wavelength.
delete According to claim 1,
Each of the first optical power information transmitting step, the second optical power information transmitting step and the third optical power information transmitting step,
An optical power information frequency modulating step of frequency-modulating each of the first to third optical power information with a carrier and a low-carrier subcarrier that modulates communication data transmitted from the optical path termination device to the optical subscriber device;
A demodulation optical signal generating step of synthesizing the subcarrier with the carrier;
A demodulation optical signal transmission step of transmitting the demodulated optical signal;
Method for controlling the wavelength of the transmitted optical signal, characterized in that comprises a.
According to claim 3,
Each of the first optical power information receiving step, the second optical power information receiving step, and the third optical power information receiving step,
A method of adjusting the wavelength of a transmitted optical signal, characterized in that the demodulated optical signal is passed through a low-pass filter to separate the sub-carrier signal, and demodulated separated sub-carrier signal to obtain optical power information.
According to claim 3,
The optical power information frequency modulation step,
Transmitting light, characterized in that the modulation frequency for at least one of the logic 1 or logic 0 of the digital light power information converted to digital power information is matched with the baud rate of the digital light power information. How to adjust the wavelength of a signal.
In the optical network for performing data communication through at least one filter formed to attenuate the signal of a frequency that deviates from the center frequency with a predetermined wavelength as the center frequency between the first optical signal transmission and reception module and the second optical signal transmission and reception module. ,
In the first optical signal transmission and reception module,
(a) generating a first uplink optical signal having a predetermined first wavelength and transmitting it to the second optical signal transmitting and receiving module;
(b) generating and transmitting first to third uplink optical signals having a first wavelength, a second wavelength smaller than the first wavelength, and a third wavelength larger than the first wavelength, respectively, to the second optical signal transmission and reception module;
(c) in the second optical signal transmission / reception module,
An optical power information detection step of detecting the power of the first to third uplink optical signals through the filter and digitally informing the first to third optical powers of the power information;
A subcarrier modulation step of modulating the detected optical power information as a subcarrier;
Transmitting first to third downlink optical signals including the subcarrier modulated signal;
(d) In the first optical signal transmission / reception module,
An optical power information demodulating step of separating subcarriers included in the first to third downlink optical signals and demodulating information of the first to third optical powers;
By comparing the optical power information of the demodulated first to third optical power,
If the first optical power information is the largest, it is determined that there is no wavelength shift and the first wavelength is not changed;
If the second optical power information is the largest, it is determined that there is a long wavelength shift, and the first wavelength is changed to a second wavelength;
If the third optical power information is the largest, it is determined that there is a short wavelength shift, and the first wavelength is changed to a third wavelength;
A method of changing the wavelength of a transmitted optical signal, characterized in that steps (a) to (d) are repeated.
An optical communication network comprising an optical fiber termination device, an optical subscriber device, and at least one periodic repetitive optical wavelength filter (Cyclic AWG),
The optical fiber termination device,
An upward optical signal receiver configured to receive an upward optical signal transmitted from the optical subscriber device and received through the periodic repeating optical wavelength filter;
An optical power detector configured to detect optical power of the received upward optical signal;
A subcarrier signal generator configured to generate a subcarrier signal including the detected optical power information;
A downlink optical signal generator configured to generate a downlink optical signal including the subcarrier signal;
A downward optical signal transmission unit transmitting the downward optical signal to the optical subscriber device;
It comprises,
The optical subscriber device,
A wavelength-adjustable upward optical signal generator for generating an upward optical signal of a predetermined wavelength transmitted to the optical fiber termination device;
An uplink optical signal transmitter for transmitting the uplink optical signal at the end of the optical path;
A downward optical signal receiver configured to receive a downward optical signal including optical power information transmitted from the optical fiber termination device;
A low pass filter for separating a subcarrier signal including optical power information of an uplink optical signal from the received downlink optical signal;
A wavelength adjusting signal generator for generating a signal for adjusting the wavelength of the uplink optical signal generated by the uplink optical signal generator based on the optical power information of the uplink optical signal included in the subcarrier signal;
It comprises,
The upward optical signal is a first oscillation wavelength optical signal having a first oscillation wavelength, a second oscillation wavelength optical signal having a wavelength smaller than the first oscillation wavelength, and a third oscillation wavelength optical signal having a wavelength larger than the first oscillation wavelength. Is composed,
The optical power information of the uplink optical signal included in the downlink optical signal includes first optical power information, second optical power information, and third optical power information that are optical power information at the receiving end of the first to third oscillation wavelength optical signals. Composed,
The wavelength control signal generation unit,
By comparing the first to third optical power information, if the first optical power information is the largest, it is determined that there is no wavelength shift, and when the second optical power information is the largest, it is determined that there is a long wavelength shift, and the third If the optical power information is the largest, it is judged that there is a short wavelength shift.
The wavelength-adjustable upward optical signal generation unit,
It comprises a light generating laser and a TEC (Thermo-Electronic Cooler) device coupled thereto,
When it is determined that there is a short wavelength shift according to the wavelength control signal, the temperature of the TEC device is adjusted to increase the wavelength of the first oscillation wavelength optical signal,
And when it is determined that there is a long wavelength shift, the temperature of the TEC device is adjusted so that the wavelength of the first oscillation wavelength optical signal is reduced.
An optical signal generator for generating a transmitted optical signal;
An optical signal transmission unit for transmitting the generated transmission optical signal to an external device;
An optical signal receiving unit receiving a received optical signal including a subcarrier signal including optical power information of the transmitted optical signal received from the external device;
And a received optical signal analyzer for acquiring and analyzing information on the transmitted optical signal received from the external device from the received optical signal.
In the received optical signal analysis unit, information of the transmitted optical signal received from the external device from the received optical signal is optical power information of the transmitted optical signal received from the external device,
The received optical signal analysis unit,
First optical power information, which is optical power information received from an external device, in a first transmission optical signal transmitted as an optical signal having a first wavelength;
Second optical power information that is optical power information received from an external device, the second transmission optical signal transmitted as an optical signal having a second wavelength smaller than the first wavelength;
Third optical power information, which is optical power information received from an external device, for a third transmitted optical signal transmitted as an optical signal having a third wavelength larger than the first wavelength;
By comparing,
When the first optical power information is the largest, it is determined that there is no wavelength shift, and the control signal maintaining the wavelength of the currently transmitted optical signal is transmitted to the optical signal generator.
When the second optical power information is the largest, it is determined that there is a long wavelength shift and transmits a control signal to reduce the wavelength of the transmitted optical signal to the optical signal generator,
When the second optical power information is the largest, it is determined that there is a short wavelength shift, and a control signal for increasing the wavelength of the transmitted optical signal is transmitted to the optical signal generator,
The optical signal generator,
The optical transceiver, characterized in that for changing the wavelength of the transmitted optical signal generated by the optical signal generator according to the wavelength shift determination of the received optical signal analysis unit.
The method of claim 8,
The optical signal generator,
Laser diodes;
A TEC device provided adjacent to the laser diode to control the temperature of the laser diode;
Optical transceiver, characterized in that comprises a.
The method of claim 9,
The laser diode,
And an optical transceiver configured to generate optical signals of different wavelengths according to the heat generation amount of the TEC device.
The method according to any one of claims 8 to 10,
The received optical signal analysis unit,
When it is determined that there is a long wavelength shift, the control signal for adjusting the wavelength of the transmitted optical signal to the second wavelength is transmitted to the optical signal generator,
If it is determined that there is a short wavelength shift, the optical transceiver, characterized in that for transmitting a control signal for adjusting the wavelength of the transmitted optical signal to the third wavelength to the optical signal generator.
The method according to any one of claims 8 to 10,
The received optical signal analysis unit,
When it is determined that there is a long wavelength shift, a control signal for adjusting the wavelength of the transmitted optical signal to a wavelength smaller than a first wavelength by a predetermined value is transmitted to the optical signal generator,
If it is determined that there is a short wavelength shift, the optical transceiver, characterized in that for transmitting a control signal for adjusting the wavelength of the transmitted optical signal to a wavelength larger than the first wavelength by a predetermined value.
The method according to any one of claims 8 to 10,
The optical signal generator,
Optical transceiver characterized in that it generates an optical signal having a wavelength belonging to any one of the O-band region (1260 ~ 1360nm), E-band region (1361 ~ 1460nm), S-band region (1461 ~ 1530nm) .
An optical path termination device that transmits a downlink optical signal multiplexed in wavelength to at least one optical subscriber device;
At least one optical subscriber device that transmits an upward optical signal to the optical fiber termination device;
A first periodic repeating optical wavelength filter (Cyclic AWG) for transmitting the downlink optical signal to the at least one optical subscriber device;
A second main-based dual wavelength filter (Cyclic AWG) for transmitting the upward optical signal to the optical fiber termination device;
It comprises,
The optical subscriber device is a wavelength division passive optical network comprising the optical transceiver of claim 12.
The method of claim 14,
The optical fiber termination device,
An optical power detector for detecting optical power of the upward optical signal;
A subcarrier modulator for modulating the optical power information of the detected uplink optical signal into a very low frequency subcarrier;
A downlink signal generator that generates a downlink optical signal including the subcarrier;
Wavelength division passive optical network, characterized in that comprises a.
The method of claim 15,
The subcarrier modulator,
Wavelength characterized in that the modulation frequency for at least one of the logic 1 or logic 0 of the digital optical power information converted from the optical power information to digital matches the baud rate of the digital optical power information. Split passive optical network.

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