CN110456453B - Optical communication apparatus, optical communication method, and computer-readable medium - Google Patents
Optical communication apparatus, optical communication method, and computer-readable medium Download PDFInfo
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- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/27—Optical coupling means with polarisation selective and adjusting means
- G02B6/2746—Optical coupling means with polarisation selective and adjusting means comprising non-reciprocal devices, e.g. isolators, FRM, circulators, quasi-isolators
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- G02B6/26—Optical coupling means
- G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
- G02B6/2804—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals forming multipart couplers without wavelength selective elements, e.g. "T" couplers, star couplers
- G02B6/2861—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals forming multipart couplers without wavelength selective elements, e.g. "T" couplers, star couplers using fibre optic delay lines and optical elements associated with them, e.g. for use in signal processing, e.g. filtering
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Abstract
Embodiments of the present disclosure provide an optical communication apparatus, an optical communication method, and a computer-readable medium. The optical communication apparatus described herein includes a laser, an optical circulator, a microwave photonic filter, and an optical-to-electrical converter. The laser is configured to generate a seed optical signal. An optical circulator is configured to transmit the seed optical signal to a colorless optical network unit and to receive an upstream optical signal modulated on the seed optical signal from the colorless optical network unit. The microwave photonic filter is configured to filter the modulated uplink optical signal to suppress stimulated brillouin scattering beat noise in the modulated uplink optical signal to generate a filtered optical signal. An optical-to-electrical converter is configured to convert the filtered optical signal to an electrical signal.
Description
Technical Field
Embodiments of the present disclosure relate generally to communication technology, and more particularly, to an optical communication apparatus, an optical communication method, and a computer-readable medium.
Background
With the increasing demand for voice, data, digital television triple-play services and bandwidth consuming applications, various types of optical access networks have been proposed to implement fiber-to-the-home services. Among these different types of optical access networks, a loop-back optical network (loop-back PON) is considered as one of the most promising schemes because it has a simple structure and a centralized control architecture. In a loopback PON, if a fixed wavelength laser is employed in an Optical Network Unit (ONU), a complex temperature control circuit should be integrated within the transmitter motherboard to avoid wavelength detuning (detuning) due to self-heating effects. However, by employing colorless ONUs, the upstream wavelength can be automatically adjusted by the Optical Line Terminal (OLT), thereby making it possible to ensure a cost-effective and easy-to-maintain PON structure.
In a loopback PON, a seed optical signal is generated in the OLT. The seed light is sent to the corresponding colorless ONU for re-modulation of the upstream signal after passing through the optical fiber and Optical Distribution Network (ODN). By using such colorless ONUs, the upstream signal can be modulated on the seed optical signal, and the re-modulated seed optical signal is reflected back in the upstream direction. In the OLT, an optical circulator is used to separate an upstream optical signal from a downstream optical signal. To compensate for the link loss of the optical fiber and the optical power splitter, high power downstream seed light is required, which will cause the Stimulated Brillouin Scattering (SBS) effect. The SBS effect will generate SBS beat noise (beat noise). Therefore, how to suppress the SBS beat noise becomes a practical problem.
Disclosure of Invention
Embodiments of the present disclosure provide an optical communication apparatus, an optical communication method, and a computer-readable medium.
In a first aspect, embodiments of the present disclosure provide an optical communication device. The optical communication device includes a laser, an optical circulator, a microwave photonic filter, and an optical-to-electrical converter. The laser is configured to generate a seed optical signal. An optical circulator is configured to transmit the seed optical signal to a colorless optical network unit and to receive an upstream optical signal modulated on the seed optical signal from the colorless optical network unit. The microwave photonic filter is configured to filter the modulated uplink optical signal to suppress stimulated brillouin scattering beat noise in the modulated uplink optical signal to generate a filtered optical signal. An optical-to-electrical converter is configured to convert the filtered optical signal to an electrical signal.
In some embodiments, a microwave photonic filter includes: a polarization beam splitter configured to split the modulated upstream optical signal received from the optical circulator into a first optical beam and a second optical beam and to couple the first optical beam and the second optical beam to a first optical branch and a second optical branch, respectively, the first optical branch being configured to subject the first optical beam to a predetermined delay to obtain a delayed first optical beam, the first optical beam and the second optical beam having orthogonal polarization states; and a light coupler configured to couple the delayed first and second light beams to the photoelectric converter.
In some embodiments, the predetermined delay is determined based on a difference between a center frequency of the seed optical signal and a center frequency of the upstream optical signal.
In some embodiments, the first optical branch comprises an optical delay line configured to impart a predetermined delay to the first optical beam.
In some embodiments, the microwave photonic filter comprises a single-mode to multi-mode coupler, a power distribution ratio of the single-mode to multi-mode coupler being determined based on a difference between a center frequency of the seed optical signal and a center frequency of the upstream optical signal.
In a second aspect, embodiments of the present disclosure provide an optical communication method. The method comprises the following steps: generating a seed optical signal; transmitting the seed optical signal to a colorless optical network unit; receiving an upstream optical signal modulated on a seed optical signal from a colorless optical network unit; filtering the modulated uplink optical signal to suppress stimulated brillouin scattering beat frequency noise in the modulated uplink optical signal, thereby generating a filtered signal; and converting the filtered signal into an electrical signal.
In some embodiments, filtering the modulated upstream optical signal comprises: splitting the modulated upstream optical signal into a first beam and a second beam, the first and second beams having orthogonal polarization states; coupling the first and second light beams to the first and second optical branches, respectively; performing a predetermined delay on the first light beam through the first optical branch to obtain a delayed first light beam; and combining the delayed first and second light beams.
In some embodiments, the method further comprises: the predetermined delay is determined based on a difference between a center frequency of the seed optical signal and a center frequency of the upstream optical signal.
In some embodiments, the first optical branch comprises an optical delay line; and delaying the first beam by a predetermined delay comprises delaying the first beam by a predetermined delay through an optical delay line.
In some embodiments, filtering the modulated upstream optical signal comprises: determining a power distribution ratio of the single mode to the multimode coupler based on a difference between a center frequency of the seed optical signal and a center frequency of the upstream optical signal; and filtering the modulated upstream optical signal by a single-mode to multi-mode coupler.
In a third aspect, embodiments of the present disclosure provide a computer readable medium having a computer program stored thereon. The computer program comprises instructions which, when executed by the processor, cause the processor to perform the method according to the second aspect.
This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the disclosure, nor is it intended to be used to limit the scope of the disclosure.
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The foregoing and other objects, features and advantages of the disclosure will be apparent from the following more particular descriptions of exemplary embodiments of the disclosure as illustrated in the accompanying drawings wherein like reference numbers generally represent like parts throughout the exemplary embodiments of the disclosure.
FIG. 1(a) shows a schematic diagram of an ideal upstream optical signal reception;
FIG. 1(b) shows a schematic diagram of impaired upstream optical signal reception;
fig. 2 illustrates a schematic diagram of an optical communication system, in accordance with certain embodiments of the present disclosure;
fig. 3 shows a schematic diagram of an optical communication system according to some other embodiments of the present disclosure;
fig. 4 shows a flow chart of an optical communication method according to an embodiment of the present disclosure;
fig. 5 illustrates a graph of the power of an SBS carrier versus the power of a seed optical signal in accordance with an embodiment of the disclosure;
6(a) and 6(b) show spectral plots with different seed optical signal powers according to an embodiment of the present disclosure;
FIG. 7 shows a frequency response graph of a microwave photonic filter according to an embodiment of the present disclosure;
FIG. 8 shows a graph comparing Bit Error Rate (BER) performance with a microwave photonic filter according to an embodiment of the present disclosure and BER performance without a microwave photonic filter; and
fig. 9 illustrates a block diagram of an apparatus suitable for implementing certain embodiments of the present disclosure.
Detailed Description
Some example embodiments will be described below with reference to the accompanying drawings. While certain embodiments of the present disclosure are shown in the drawings, it is to be understood that the present disclosure may be embodied in various forms and should not be construed as limited to the embodiments set forth herein, but rather are provided for a more thorough and complete understanding of the present disclosure. It should be understood that the drawings and embodiments of the disclosure are for illustration purposes only and are not intended to limit the scope of the disclosure.
The term "passive optical network" or "PON" as used herein means that the Optical Distribution Network (ODN) it comprises consists of passive devices such as optical splitters and optical fibers, without the need for any active devices.
The term "optical communication device" as used herein refers to any suitable device or entity in an optical communication network that is capable of optical communication with an Optical Network Unit (ONU). For ease of discussion, in some embodiments, an Optical Line Terminal (OLT) is used as an example of an optical communication device.
The term "optical line terminal" or "OLT" as used herein refers to a device in a PON that serves end users as a service providing node. The OLT may, for example, provide an electrical-to-optical conversion function to send data out through an optical fiber in the ODN.
The term "optical network unit" or "ONU" as used herein refers to a client node connected to an OLT by an optical fiber to receive user data from the OLT.
The term "circuitry" as used herein refers to one or more of the following:
(a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry); and
(b) a combination of hardware circuitry and software, such as (if applicable): (i) a combination of analog and/or digital hardware circuitry and software/firmware, and (ii) any portion of a hardware processor and software (including a digital signal processor, software, and memory that work together to cause an apparatus, such as an OLT or other computing device, to perform various functions); and
(c) a hardware circuit and/or processor, such as a microprocessor or a portion of a microprocessor, that requires software (e.g., firmware) for operation, but may lack software when software is not required for operation.
The definition of circuit applies to all usage scenarios of this term in this application, including any claims. As another example, the term "circuitry" as used herein also covers an implementation of merely a hardware circuit or processor (or multiple processors), or a portion of a hardware circuit or processor, or software or firmware accompanying it. For example, the term "circuitry" would also cover a baseband integrated circuit or processor integrated circuit or a similar integrated circuit in an OLT or other computing device, as applicable to the particular claim element.
The terms "include" and variations thereof as used herein are inclusive and open-ended, i.e., "including but not limited to. The term "based on" is "based, at least in part, on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment". Relevant definitions for other terms will be given in the following description.
Fig. 1(a) shows a schematic diagram of ideal upstream optical signal reception, and fig. 1(b) shows a schematic diagram of impaired upstream optical signal reception. As shown in fig. 1(a), a seed optical signal 110 generated by a laser in an optical communication device is transmitted to an ONU via a single-mode fiber (SMF) 112. The ONU modulates the upstream optical signal to be transmitted onto the seed optical signal 110, and then transmits the modulated upstream optical signal 114 to the optical communication device. Since the power of the seed optical signal 110 is below the SBS threshold, the SBS beat frequency noise is small, so that the complete modulated upstream optical signal 114 can be obtained.
As shown in fig. 1(b), a seed optical signal 120 generated by a laser in an optical communication device is transmitted to an ONU via a single-mode fiber (SMF) 112. The ONU modulates the upstream optical signal to be transmitted onto the seed optical signal 120, and then transmits the modulated upstream optical signal 124 to the optical communication device. Since the power of the seed optical signal 120 is above the SBS threshold, a high power SBS carrier 126 is generated. The SBS carrier 126 has a predetermined frequency separation from the modulated upstream signal 124. Due to the non-linearity of the SBS effect, a portion of the energy of the seed optical signal 120 is transferred to the SBS carrier 126, which reduces the power of the seed optical signal 120 and affects the upstream power budget. In the optical communication device, both the modulated upstream signal 124 and the generated SBS carrier 126 are received by optical-to-electrical converters in the optical communication device. Therefore, SBS beat noise is generated, which causes signal distortion.
One conventional approach for suppressing SBS beat noise is to use specially designed SMFs with high SBS thresholds. Such SMF may increase the SBS threshold by approximately 3 dB. If such SMF is applied to a cable television (CATV) network, the quality of a received signal can be improved. However, this scheme is only applicable to local CATV networks with limited transmission distances. In a long-reach PON, if such SMFs having a high SBS threshold are used to replace SMFs already deployed on a large scale, excessive construction costs are incurred.
Another conventional scheme for suppressing SBS beat noise is to use a duobinary signal format. Because the duobinary signal is in a carrier-free signal format, the peak power of the duobinary signal is low, and thus the tolerance to SBS beat noise is high. Therefore, the power budget of the system can be improved by increasing the transmission power in the long-distance PON. However, the main disadvantage of this scheme is that the use of the duobinary signal to improve the tolerance to SBS beat noise will increase the complexity of the transmitter and receiver.
To address, at least in part, the above-mentioned and other potential drawbacks and problems of the prior art, embodiments of the present disclosure propose an optical communication device. According to embodiments of the present disclosure, a microwave photonic filter is employed to suppress SBS beat noise generated between a reflected SBS carrier and an upstream signal, thereby improving the performance of the upstream signal. Hereinafter, several examples of an optical communication apparatus according to embodiments of the present disclosure will be described with reference to fig. 2 to 3.
Fig. 2 shows a schematic diagram of an optical communication system 200 according to an embodiment of the present disclosure. The optical communication system 200 may include an optical communication device 210 and a colorless ONU 220. It should be understood that the optical communication system 200 may also include additional modules that are not shown and/or may omit the modules shown. The scope of the disclosed embodiments is not limited in this respect.
The optical communication device 210 includes a laser 230, an optical circulator 240, a Microwave Photonic Filter (MPF)250, and an optical-to-electrical converter 260. The laser 230 is configured to generate a seed optical signal. Optical circulator 240 is configured to transmit a seed optical signal to colorless ONU 220 and to receive an upstream optical signal modulated on the seed optical signal from colorless ONU 220. Optical circulator 240 may have multiple ports, some of which are used to transmit seed optical signals to colorless ONU 220 and some of which are used to receive modulated upstream optical signals from colorless ONU 220.
The MPF 250 is configured to filter the modulated uplink optical signal to suppress SBS beat noise in the modulated uplink optical signal to generate a filtered optical signal. The optical-to-electrical converter 260 is configured to convert the filtered optical signal into an electrical signal.
Since the MPF 250 has a very flat filtering curve in the optical domain, it can realize suppression of colorless, wavelength insensitive SBS beat noise, thereby being suitable for upstream signal detection in a loopback PON. Furthermore, since the MPF 250 may include passive optical devices, the optical communication device 210 according to an embodiment of the present disclosure is simple in structure, cost-effective, and has high reliability for SBS beat noise suppression.
It should be understood that optical communication device 210 is shown in fig. 2 as communicating with only one clear ONU for illustrative purposes only, and the scope of the disclosed embodiments is not limited thereto. Depending on the specific application scenario, the optical communication device 210 may communicate with multiple ONUs. Hereinafter, a description will be given with reference to fig. 3 taking as an example that the optical communication device 210 communicates with two ONUs.
Fig. 3 shows a schematic diagram of an optical communication system 300, in accordance with certain other embodiments of the present disclosure. The optical communication system 300 may be considered as one example implementation of the optical communication system 200 described above.
In this example, the optical circulator 240 has a first port 241, a second port 242, and a third port 243. The seed optical signal generated by the laser 230 is input into the optical circulator 240 via the first port 241 and output via the second port 242. The seed optical signal output via the second port 242 is transmitted to a Power Splitter (PS) 340 through the SMF330, and further to the first colorless ONU 320 and the second colorless ONU 322. The first and second colorless ONUs 320 and 322, respectively, modulate an upstream optical signal to be transmitted onto the received seed optical signal and transmit the modulated upstream optical signal to the optical communication device 210 via the PS 340 and the SMF 330. The modulated upstream optical signal is input to the optical circulator 240 via the second port 242 and output to the MPF 250 via the third port 243.
The MPF 250 includes a Polarization Beam Splitter (PBS)251 and an Optical Coupler (OC) 252. PBS 251 is configured to split the modulated upstream optical signal received from optical circulator 240 into a first optical beam and a second optical beam. The first and second beams have orthogonal polarization states, so that random beat noise from optical signals of the same frequency can be avoided. PBS 251 is also configured to couple the first and second light beams to first and second optical branches 253 and 254, respectively.
The first optical branch 253 is configured to delay the first light beam by a predetermined time to obtain a delayed first light beam. In this example, the first optical branch 253 includes an optical delay line 255. The optical delay line 255 is configured to apply a predetermined delay to the first light beam. In some embodiments, the predetermined delay is determined based on a difference between a center frequency of the seed optical signal and a center frequency of the upstream optical signal. The MPF 250 according to an embodiment of the present disclosure may be regarded as a Finite Impulse Response (FIR) filter. For an FIR filter of order n +1 (i.e., having n +1 taps), its discrete function can be expressed as:
y[n]＝b0x[n]+b1x[n-τ]+...+bNx[n-Nτ] (1)
wherein x [ N-N τ]Representing an input signal x n of order n]Delayed by N tau, with weights in amplitudeCoefficient bN，y[n]Representing the filtered output signal, N and N being positive integers. The frequency domain transfer function of the FIR filter can be expressed as:
where H (w) represents the frequency domain transfer function of the FIR filter, bmRepresenting the weight coefficient, and N is a positive integer.
The OC 252 is configured to couple the delayed first and second light beams to the optical-to-electrical converter 260. The optical-to-electrical converter 260 may include an Avalanche Photodiode (APD). In embodiments employing APDs, the APDs can have a bandwidth associated with the transmission rate of the optical signal. For example, an APD may have a bandwidth associated with 10Gb/s when the transmission rate of the optical signal is 10 Gb/s.
Since the MPF 250 includes passive optical devices such as the PBS 251, the OC 252, and the optical delay line 255, the optical communication device 210 according to an embodiment of the present disclosure is simple in structure and cost-effective. By using the MPF 250, the uplink BER performance can be effectively improved, and the power of the downlink seed optical signal can be increased to extend the network coverage. Furthermore, a simple binary signal format of the upstream signal may be used with the MPF of the present disclosure without employing a complex duobinary signal format to reduce peak power. Furthermore, the MPF can be used for simultaneously realizing the beat noise suppression of the uplink multi-channel SBS.
It will be appreciated that the optical communication system 200 may also be put into practice in a different manner than that shown in fig. 3. For example, instead of PBS 251, MPF 250 may include a single-mode to multi-mode coupler, thereby making MPF 250 polarization insensitive. The power splitting ratio of the single-mode to multi-mode coupler may be determined based on a difference between a center frequency of the seed optical signal and a center frequency of the upstream optical signal.
The optical communication apparatus according to the embodiment of the present disclosure is described above with reference to fig. 2 and 3, and the optical communication method 400 will be described below with reference to fig. 4.
Fig. 4 shows a flow diagram of an optical communication method 400 according to an embodiment of the present disclosure. In some embodiments, the method 400 may be implemented by the optical communication device 210 in fig. 2 or fig. 3. It is to be understood that method 400 may also include additional acts not shown and/or may omit acts shown. The scope of the disclosed embodiments is not limited in this respect.
At 410, a seed optical signal is generated. At 420, a seed optical signal is transmitted to the colorless ONU. At 430, an upstream optical signal modulated on the seed optical signal is received from the colorless ONU. At 440, the modulated uplink optical signal is filtered to suppress stimulated brillouin scattering beat noise in the modulated uplink optical signal, thereby generating a filtered signal. At 450, the filtered signal is converted to an electrical signal.
In some embodiments, filtering the modulated upstream optical signal comprises: splitting the modulated upstream optical signal into a first beam and a second beam, the first and second beams having orthogonal polarization states; coupling the first and second light beams to the first and second optical branches, respectively; performing a predetermined delay on the first light beam through the first optical branch to obtain a delayed first light beam; and combining the delayed first and second light beams.
In some embodiments, the method 400 further includes determining the predetermined delay time based on a difference between a center frequency of the seed optical signal and a center frequency of the upstream optical signal.
In some embodiments, the first optical branch comprises an optical delay line; and delaying the first beam by a predetermined delay comprises delaying the first beam by a predetermined delay through an optical delay line.
In some embodiments, filtering the modulated upstream optical signal comprises: determining a power distribution ratio of the single mode to the multimode coupler based on a difference between a center frequency of the seed optical signal and a center frequency of the upstream optical signal; and filtering the modulated upstream optical signal by a single-mode to multi-mode coupler.
It should be understood that the various features described above with reference to fig. 2 and 3 are equally applicable to the method 400, and thus, a detailed description thereof is omitted herein.
Hereinafter, performance improvement of an optical communication apparatus according to an embodiment of the present disclosure is described with reference to fig. 5 to 8.
Fig. 5 illustrates a graph of the power of the SBS carrier versus the power of the seed optical signal in accordance with an embodiment of the present disclosure. In the example of fig. 5, 25km of SMF is employed for optical signal transmission between the optical communication device and the ONU. The seed optical signal generated by the laser is transmitted to the ONU via the SMF. And the ONU modulates the uplink optical signal to be transmitted onto the seed optical signal and further transmits the modulated uplink optical signal to the optical communication equipment. Therefore, it is necessary to compensate for twice the transmission link loss. Generally, increasing the power of the seed optical signal is an effective way to improve the power budget. However, when the power of the seed optical signal is above the SBS threshold, a frequency-shifted SBS carrier will be generated, and a portion of the energy of the seed optical signal is transferred to the SBS carrier, which reduces the power of the seed optical signal and affects the upstream power budget.
As shown in fig. 5, when the power of the seed optical signal is 1dBm, the power of the SBS carrier generated is about-21.5 dBm. The measured spectrum is shown in fig. 6 (a). In this case, the bi-directional link loss is about 14dB, the uplink signal is a 10Gb/s non-return-to-zero (NRZ) signal with a signal to SBS beat noise ratio of 7.5dB, which ensures acceptable uplink reception performance. When the power of the seed optical signal increases to 4dBm, the power of the SBS carrier generated increases to-6.5 dBm. The ratio of the corresponding signal to SBS beat noise decreases and the measured spectrum is shown in figure 6 (b). Since the power of the SBS carrier is higher than that of the received uplink signal, the uplink Bit Error Rate (BER) rapidly deteriorates.
Fig. 7 shows a frequency response plot of an MPF according to an embodiment of the present disclosure. The difference between the center frequency of the seed optical signal and the center frequency of the upstream optical signal (i.e., the frequency spacing) may be determined based on the length of the SMF, the power of the seed optical signal, and the wavelength of the laser. In an embodiment where the SMF has a length of 25km, the power of the seed optical signal is 4dBm, and the wavelength of the laser is 1550nm, the frequency separation between the center frequency of the seed optical signal and the center frequency of the upstream optical signal is about 11 GHz. Thus, after photoelectric conversion, SBS beat noise is mainly located at about 11GHz in the electrical domain. The seed optical signal and the modulated upstream optical signal are filtered by the MPF to eliminate SBS beat noise at about 11 GHz. As can be seen from fig. 7, the MPF according to an embodiment of the present disclosure is used as a band-notch filter having a deep filtering curve at a frequency of about 11 GHz. By using MPF, an rejection ratio of over 60dB is achieved at a frequency of about 11GHz, achieving effective SBS beat noise rejection performance.
The predetermined delay of the first optical branch 253 of the PBS 251 relative to the second optical branch 254 is determined based on the frequency separation between the center frequency of the seed optical signal and the center frequency of the upstream optical signal, i.e., based on the frequency of the SBS beat noise. In an embodiment where SBS beat noise is predominantly located in the electrical domain at about 11GHz, the predetermined delay of the first optical branch 253 relative to the second optical branch 254 is 51 picoseconds (ps), as shown in fig. 7.
Fig. 8 shows a graph comparing BER performance when MPF according to an embodiment of the present disclosure is employed and BER performance when MPF is not employed. In the example of fig. 8, the power of the seed optical signal is 4 dBm. Without the use of MPF, high power SBS beat noise is generated due to the interaction between the SBS carrier and the upstream signal. Thus, error-free uplink reception cannot be achieved. The captured eye diagram is shown at 810, where the SBS beat noise generated is concentrated primarily at the upper edge of the eye diagram 810. After the MPF is used, error-free upstream reception is achieved, since most of the SBS beat noise at the 11GHz frequency has been suppressed, and a clear eye diagram is shown at 820.
In some embodiments, an apparatus (e.g., optical communication device 210) capable of performing method 400 may include corresponding means for performing the steps of method 400. These components may be implemented in any suitable manner. For example, it may be implemented by a circuit or a software module.
In some embodiments, the apparatus includes means for generating a seed optical signal; means for transmitting a seed optical signal to a colorless optical network unit; means for receiving an upstream optical signal modulated on a seed optical signal from a colorless optical network unit; means for filtering the modulated upstream optical signal to suppress stimulated brillouin scattering beat noise in the modulated upstream optical signal, thereby generating a filtered signal; and means for converting the filtered signal to an electrical signal.
In some embodiments, the means for filtering the modulated upstream optical signal comprises: means for splitting the modulated upstream optical signal into a first optical beam and a second optical beam, the first and second optical beams having orthogonal polarization states; means for coupling the first and second light beams to the first and second optical branches, respectively; means for delaying the first light beam by a predetermined time through the first optical branch to obtain a delayed first light beam; and means for combining the delayed first and second beams.
In some embodiments, the apparatus further comprises means for determining the predetermined delay time based on a difference between a center frequency of the seed optical signal and a center frequency of the upstream optical signal.
In some embodiments, the first optical branch comprises an optical delay line; and the means for delaying the first light beam by a predetermined delay time comprises means for delaying the first light beam by the optical delay line by a predetermined delay time.
In some embodiments, the means for filtering the modulated upstream optical signal comprises: means for determining a power splitting ratio of the single-mode to multi-mode coupler based on a difference between a center frequency of the seed optical signal and a center frequency of the upstream optical signal; and means for filtering the modulated upstream optical signal by a single-mode to multi-mode coupler.
Fig. 9 illustrates a block diagram of an apparatus 900 suitable for implementing embodiments of the present disclosure. The apparatus 900 may be used to implement an optical communication device capable of implementing the operations and functions described herein, such as the optical communication device 210 described with reference to fig. 2-8.
As shown in fig. 9, the apparatus 900 includes a processor 910. The processor 910 controls the operation and functions of the device 900. For example, in certain embodiments, the processor 910 may perform various operations by way of instructions 930 stored in a memory 920 coupled thereto. The memory 920 may be of any suitable type suitable to the local technical environment and may be implemented using any suitable data storage technology, including but not limited to semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems. Although only one memory unit is shown in FIG. 9, there may be multiple physically distinct memory units within device 900.
The processor 910 may be of any suitable type suitable to the local technical environment, and may include, but is not limited to, one or more of general purpose computers, special purpose computers, microcontrollers, digital signal controllers (DSPs), and controller-based multi-core controller architectures. The apparatus 900 may also include multiple processors 910. The device 900 may implement the reception and transmission of information by means of optical fibers or cables, etc.
The processor 910 causes the apparatus 900 to perform the relevant operations and features of the optical communication device 210 described above with reference to fig. 2-8 by executing the instructions. All of the features described above with reference to fig. 2-8 apply to the apparatus 900 and are not described in detail herein.
In general, the various example embodiments of this disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Certain aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While aspects of embodiments of the disclosure have been illustrated or described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that the blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.
By way of example, embodiments of the disclosure may be described in the context of machine-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform particular tasks or implement particular abstract data types. In various embodiments, the functionality of the program modules may be combined or divided between program modules as described. Machine-executable instructions for program modules may be executed within local or distributed devices. In a distributed facility, program modules may be located in both local and remote memory storage media.
Computer program code for implementing the methods of the present disclosure may be written in one or more programming languages. These computer program codes may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the computer or other programmable data processing apparatus, cause the functions/acts specified in the flowchart and/or block diagram block or blocks to be performed. The program code may execute entirely on the computer, partly on the computer, as a stand-alone software package, partly on the computer and partly on a remote computer or entirely on the remote computer or server.
In the context of the present disclosure, computer program code or related data may be carried by any suitable carrier to enable a device, apparatus or processor to perform various processes and operations described above. Examples of a carrier include a signal, computer readable medium, and the like.
Examples of signals may include electrical, optical, radio, acoustic, or other forms of propagated signals, such as carrier waves, infrared signals, and the like.
The computer readable medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination thereof. More detailed examples of a computer-readable storage medium include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical storage device, a magnetic storage device, or any suitable combination thereof.
Additionally, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In some cases, multitasking or parallel processing may be beneficial. Likewise, while the above discussion contains certain specific implementation details, this should not be construed as limiting the scope of any invention or claims, but rather as describing particular embodiments that may be directed to particular inventions. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination.
Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.
Claims (8)
1. An optical communication device comprising:
a laser configured to generate a seed optical signal;
an optical circulator configured to transmit the seed optical signal to a colorless optical network unit and to receive an upstream optical signal modulated on the seed optical signal from the colorless optical network unit;
a microwave photonic filter configured to filter the modulated uplink optical signal to suppress stimulated Brillouin scattering beat noise in the modulated uplink optical signal, thereby generating a filtered optical signal; and
an optical-to-electrical converter configured to convert the filtered optical signal into an electrical signal;
wherein the microwave photonic filter comprises:
a polarization beam splitter configured to split the modulated upstream optical signal received from the optical circulator into a first optical beam and a second optical beam and to couple the first and second optical beams to a first optical branch and a second optical branch, respectively, the first optical branch configured to subject the first optical beam to a predetermined delay to obtain a delayed first optical beam, the first and second optical beams having orthogonal polarization states; and
a light coupler configured to couple the delayed first light beam and the second light beam to the photoelectric converter.
2. The optical communication device of claim 1, wherein the predetermined delay is determined based on a difference between a center frequency of the seed optical signal and a center frequency of the upstream optical signal.
3. The optical communication device of claim 1, wherein the first optical branch comprises an optical delay line configured to impart the predetermined delay to the first optical beam.
4. An optical communication method, comprising:
generating a seed optical signal;
transmitting the seed optical signal to a colorless optical network unit;
receiving an upstream optical signal modulated on the seed optical signal from the colorless optical network unit;
filtering the modulated uplink optical signal to suppress stimulated Brillouin scattering beat frequency noise in the modulated uplink optical signal, thereby generating a filtered signal; and
converting the filtered signal into an electrical signal;
wherein filtering the modulated upstream optical signal comprises:
splitting the modulated upstream optical signal into a first optical beam and a second optical beam, the first and second optical beams having orthogonal polarization states;
coupling the first and second light beams to first and second optical branches, respectively;
-delaying the first light beam by a predetermined delay through the first optical branch to obtain a delayed first light beam; and
combining the delayed first light beam and the second light beam.
5. The optical communication method of claim 4, further comprising:
determining the predetermined delay time based on a difference between a center frequency of the seed optical signal and a center frequency of the upstream optical signal.
6. The optical communication method of claim 4, wherein:
the first optical branch comprises an optical delay line; and is
The predetermined delaying of the first light beam comprises the predetermined delaying of the first light beam by the optical delay line.
7. An apparatus, comprising:
at least one processor; and
at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to perform the method of any of claims 4-6.
8. A computer-readable medium, on which a computer program is stored, the computer program comprising instructions which, when executed by a processor, cause the processor to carry out the method according to any one of claims 4-6.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101272186A (en) * | 2007-03-22 | 2008-09-24 | 日本电气株式会社 | Transceiver for optical transmission and transmission method for the same |
| CN101389148A (en) * | 2008-10-29 | 2009-03-18 | 上海大学 | Structure of uplink and downlink of radio frequency optical fiber transmission system and method of providing optical carrier for uplink |
| CN102075239A (en) * | 2009-11-20 | 2011-05-25 | 康宁光缆系统有限公司 | Optical transmitters for mm-wave ROF systems |
| CN103940513A (en) * | 2014-03-27 | 2014-07-23 | 华中科技大学 | Method used for improving spectral measurement dynamic range and spectral measurement system |
| CN106200207A (en) * | 2016-07-26 | 2016-12-07 | 哈尔滨理工大学 | Pattern Filter method and device for photon-phonon coupling photonic device |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008139784A (en) * | 2006-12-05 | 2008-06-19 | Sumitomo Electric Ind Ltd | Optical signal noise suppression device and optical signal noise suppression method |
-
2018
- 2018-05-08 CN CN201810433139.3A patent/CN110456453B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101272186A (en) * | 2007-03-22 | 2008-09-24 | 日本电气株式会社 | Transceiver for optical transmission and transmission method for the same |
| CN101389148A (en) * | 2008-10-29 | 2009-03-18 | 上海大学 | Structure of uplink and downlink of radio frequency optical fiber transmission system and method of providing optical carrier for uplink |
| CN102075239A (en) * | 2009-11-20 | 2011-05-25 | 康宁光缆系统有限公司 | Optical transmitters for mm-wave ROF systems |
| CN103940513A (en) * | 2014-03-27 | 2014-07-23 | 华中科技大学 | Method used for improving spectral measurement dynamic range and spectral measurement system |
| CN106200207A (en) * | 2016-07-26 | 2016-12-07 | 哈尔滨理工大学 | Pattern Filter method and device for photon-phonon coupling photonic device |
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