CN104113375A - Optical communication transmitting end, receiving end, system and data transmitting and receiving method - Google Patents

Abstract

The invention relates to the field of optical communication, and discloses a transmitting end, a receiving end, a system of optical communication and a data sending and receiving method thereof. In the present invention, an optical filter is used at the transmitting end or receiving end of the optical communication to perform asymmetric filtering on the user's signal. Compared with the existing technology, regardless of whether the optical filter bank is located at the transmitting end or the receiving end, the transmission performance of the system can be improved, and the information transmission rate of the system can be improved; at the same time, the structure of the existing communication system is not changed, the cost is low, and it is easy to implement.

Description

Transmitting end, receiving end, system and data sending and receiving method of optical communication

technical field

The invention relates to the field of optical communication, in particular to a transmitting end, a receiving end, a system of optical communication and a data sending and receiving method thereof.

Background technique

At present, in order to achieve high-speed short-distance signal transmission and increase the single-channel transmission rate, the transmitter of the communication system usually uses a carrierless amplitude-phase modulation (CAP) transmitter to transmit the signal and output it to the receiver through optical fiber. . Wherein, the carrier-free amplitude-phase modulation transmitter includes an encoder for encoding each user's signal and a directly modulated laser for modulating the encoded user's signal into the generated optical signal.

However, due to the influence of directly modulated laser chirp and fiber dispersion, the rate of communication transmission system is severely limited.

Contents of the invention

The purpose of the present invention is to provide a transmitting end, receiving end, system and data sending and receiving method of optical communication, which can improve the transmission performance and rate of the system, and are low in cost and easy to implement.

In order to solve the above technical problems, an embodiment of the present invention provides a transmitting end of optical communication, including: a CAP transmitter and an optical filter; the transmission signal of the CAP transmitter is asymmetrically filtered by the optical filter and then sent to the receiving end.

The embodiment of the present invention also provides a receiving end of optical communication, including: an optical filter, an optical detector, and a decoding demodulator;

After the optical filter asymmetrically filters the signal from the transmitting end, the optical detector directly detects the filtered optical signal and converts it into an electrical signal; the decoding demodulator performs Decode and demodulate.

An embodiment of the present invention also provides an optical communication system, including: the above-mentioned transmitting end of optical communication;

Or, the receiving end of the above-mentioned optical communication.

The embodiment of the present invention also provides a data transmission method of optical communication, comprising the following steps:

The transmitted signal is asymmetrically filtered by the transmitting end and sent out.

The embodiment of the present invention also provides a data receiving method for optical communication, including the following steps:

The receiving end performs asymmetric filtering on the signal sent by the sending end;

Directly detect the asymmetrically filtered signal and convert it into an electrical signal;

The electrical signal is decoded and demodulated.

Compared with the prior art, the embodiments of the present invention can suppress the chirp frequency generated by the built-in direct modulation laser of the CAP transmitter in the transmitting end and increase the modulation frequency regardless of whether the optical filter is located at the transmitting end or the receiving end of the optical communication. The opening of the eye diagram of the signal improves the transmission performance of the system; moreover, due to the suppression of the chirp frequency generated by the directly modulated laser, the filtering effect of the optical filter is not symmetrical to the double-sided band signal generated by the optical up-conversion, which destroys the double-sided band The symmetry of the signal can weaken the distortion introduced by dispersion during direct detection, and realize higher rate information transmission in the system; at the same time, without changing the structure of the existing communication system, the optical filter bank is directly introduced at the transmitting end or receiving end, and the cost is low ,Easy to implement.

In addition, the optical filter may be a bandpass filter or a bandstop filter. In this way, the flexibility of the embodiment of the present invention is ensured.

Description of drawings

FIG. 1 is a schematic structural diagram of a transmitting end of an optical communication according to a first embodiment of the present invention;

Fig. 2 is a schematic diagram showing the influence of the parameters of the optical filter on the system performance according to the first embodiment of the present invention;

3 is a schematic structural diagram of a receiving end of optical communication according to a second embodiment of the present invention;

4 is a schematic structural diagram of an optical communication system according to a third embodiment of the present invention;

Fig. 5 is a schematic structural diagram of an optical communication system according to a fourth embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, various embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. However, those of ordinary skill in the art can understand that, in each implementation manner of the present invention, many technical details are provided for readers to better understand the present application. However, even without these technical details and various changes and modifications based on the following implementation modes, the technical solution claimed in each claim of the present application can be realized.

The first embodiment of the present invention relates to a transmitting end of optical communication, including: a CAP transmitter and an optical filter; the transmitting signal of the CAP transmitter is asymmetrically filtered by the optical filter and then sent to the receiving end.

In this embodiment, the transmitting end of optical communication, as specifically shown in FIG. 1 , includes: CAP transmitters of N users, an optical filter bank 101 and a wavelength division multiplexer 102, where N is a natural number, and the optical filtering The filter group 101 includes N optical filters 1011 , and one end of each optical filter 1011 is connected to the user's CAP transmitter in a one-to-one correspondence, and the other end is connected to the wavelength division multiplexer 102 .

Specifically, the CAP transmitter of each user performs carrier-free amplitude-phase modulation and multi-stage coding on the corresponding user's signal, wherein the user's signal is an optical signal carrying user information. Multi-stage coding is performed on the signals of each user, and carrier-free amplitude-phase modulation based on a direct modulator (not shown) is performed to increase the transmission bit rate. For example, in this embodiment, the transmitter includes CAP transmitters of N users, that is, the CAP transmitter of user 1, the CAP transmitter of user 2, ..., the CAP transmitter of user N, and the CAP transmitter of user 1 There is no carrier amplitude-phase modulation and multi-order coding for the signal of user 1, no carrier amplitude-phase modulation and multi-order coding for the signal of user 2 by the CAP transmitter of user 2, ..., the CAP transmitter of user N for the signal of user N Carrier-free amplitude-phase modulation and multi-order coding.

The optical filter bank 101 performs asymmetric filtering on the received signal. Specifically, each optical filter 1011 in the optical filter bank 101 asymmetrically filters the received signal, and outputs the asymmetrically filtered signal to the wavelength division multiplexer 102 .

In this implementation manner, the optical filter 1011 may be a band-pass filter. A band-pass filter only allows signals in a specific frequency band to pass while blocking signals in other frequency bands. For example, the band-pass filter correspondingly connected to the CAP transmitter of user 1 only allows the signal of a specific frequency carrying the information of user 1 to pass through, and shields signals of other frequencies. In this way, interference can be eliminated and the performance of signal transmission can be improved.

Since the carrier concentration of the DFB-LD (Distributed Feedback Laser) built in the CAP transmitter is affected by the driving current, when the intensity modulation of the DFB-LD is performed, chirp is inevitably introduced, so that the directly modulated signal is not only affected by In addition to amplitude modulation, there is concomitant frequency modulation, resulting in broadening of the output spectrum. In direct intensity modulation, due to the existence of adiabatic chirp, the transient output wavelength of the laser at 0 code and 1 code is different. When the modulation signal is 0 yards, the laser output wavelength is on the long wavelength side; when the modulation signal is 1 yard, the laser output wavelength is blue-shifted. Under direct modulation conditions, the output spectrum of the distributed feedback laser is a double-peak structure, and its wavelength interval depends on the linewidth enhancement factor, adiabatic chirp coefficient, and external driving current determined by the material of the distributed feedback laser itself. Because the spectral broadening of the directly modulated laser causes the user's signal to be distorted, and after the user's signal is transmitted through the optical fiber, it is more affected by the dispersion of the optical fiber. The asymmetric filtering technology is to use the general optical filter 1011 to shape the spectrum of the user's signal. Due to the chirp frequency shift, the center wavelength of the optical filter 1011 has a certain offset from the signal wavelength, so it is called asymmetric.

Since the optical filter bank 101 performs asymmetric filtering on the signal, it can suppress the chirp frequency generated by the built-in direct modulation lasers of the CAP transmitters of N users at the transmitting end, increase the eye opening of the modulated signal, and thus improve the transmission of the system performance; and, due to suppression of the chirp frequency produced by the directly modulated laser (not shown), the filtering effect of the optical filter 1011 is not symmetrical for the double sideband signal due to optical up-conversion, destroying the symmetry of the double sideband signal, Therefore, the distortion introduced by dispersion can be weakened when the receiving end adopts the direct detection method, and a higher rate information transmission of the system can be realized; at the same time, since the structure of the existing communication system is not changed, the optical filter bank 101 is directly introduced at the transmitting end, and the cost is low ,Easy to implement.

The wavelength division multiplexer 102 combines the N asymmetrically filtered signals and outputs them to the receiving end through the optical fiber 103 . In this embodiment, the wavelength division multiplexer 102 combines N kinds of asymmetrically filtered signals (ie, optical carrier signals) of different wavelengths together, and couples them into the optical fiber 103 for transmission. The wavelength division multiplexer 102 is an existing and mature device, and will not be repeated here.

Further, in order to increase the transmission rate of the system, high-order modulation is usually used. Since the asymmetric filtering technology only filters out the chirp frequency and does not cause damage to the user's signal spectrum, in the present invention, the transmitting end is transparent to the modulation order, that is, it is transparent to various modulation orders. Applicable and practical.

In addition, the optical filter may also be a band rejection filter. The band-stop filter can allow waves of specific frequency components to pass through, but attenuates waves of other frequency components to an extremely low level, which can reduce interference to effective signals, improve signal transmission performance, and ensure the flexibility of the embodiment of the present invention.

Among them, the influence of the parameters of the band-pass filter and the band-stop filter on the system performance is shown in Fig. 2 . Wherein, the horizontal axis is the frequency offset, the unit is gigahertz (GHz), the vertical axis is the bit error rate, 201 is the back-to-back transmission (BTB) of the band-pass filter, and 202 is the back-to-back transmission (BTB) of the band-stop filter, 203 is the transmission of the band-pass filter after 15 km, and 204 is the transmission of the band-stop filter after 15 km, wherein, the back-to-back transmission does not pass through the transmission fiber. In addition, it can be seen from Figure 2 that the performance of the band-pass filter and the band-stop filter are similar and will not be affected by the transmission link.

Compared with the existing technology, the optical filter can suppress the chirp frequency generated by the direct modulation laser built in the CAP transmitter at the transmitting end, and increase the eye opening of the modulated signal, thereby improving the transmission performance of the system; moreover, the system can be realized Information transmission at a higher rate; at the same time, the structure of the existing communication system is not changed, the cost is low, and it is easy to implement.

The second embodiment of the present invention relates to a receiving end of optical communication, including: an optical filter, an optical detector, and a decoding demodulator; after the optical filter asymmetrically filters the signal from the transmitting end, the optical detector The filtered optical signal is directly detected and converted into an electrical signal; the decoding demodulator decodes and demodulates the electrical signal.

In this embodiment, the receiving end of optical communication, as specifically shown in FIG. 3 , includes: a demultiplexer 301, an optical filter bank 101, N optical detectors and N decoding demodulators, 101 includes N optical filters 1011, wherein the optical filters 1011, optical detectors and decoding demodulators correspond one-to-one, and one end of each optical filter 1011 is connected to the demultiplexer 301, and the other end is connected to the The photodetectors are connected in a one-to-one correspondence. Each optical filter 1011 asymmetrically filters the optical carrier signals of N wavelengths output by the demultiplexer 301, and outputs them to corresponding optical detectors.

In this implementation manner, the optical filter 1011 may be a band-pass filter. Bandpass filters allow only certain frequency bands to pass while blocking signals from other frequency bands. In this way, interference can be eliminated and the performance of signal transmission can be improved.

In addition, the optical filter may also be a band rejection filter. The band-stop filter can allow waves of specific frequency components to pass through, but attenuates waves of other frequency components to an extremely low level, which can reduce interference to effective signals, improve signal transmission performance, and ensure the flexibility of the embodiment of the present invention.

Compared with the existing technology, the optical filter bank 101 performs asymmetric filtering on the signal at the receiving end, which can also suppress the chirp frequency generated by the direct modulation laser built in the CAP transmitter at the transmitting end, and increase the eye opening of the modulated signal , thereby improving the transmission performance of the system; and, since the chirp frequency produced by the directly modulated laser (not shown) is suppressed, the filtering effect of the optical filter 1011 is not symmetrical for the double-sideband signal produced by the optical up-conversion, and also destroys The symmetry of the double-sideband signal is improved, which can weaken the distortion introduced by the dispersion when the receiving end adopts the direct detection method, and realize the information transmission of the system at a higher rate; at the same time, the structure of the existing communication system is not changed, and the receiving end can directly The introduction of the optical filter bank 101 is low in cost and easy to implement.

It should be noted that no matter whether the optical filter bank is located at the transmitting end or the receiving end, it can suppress the chirp frequency generated by the directly modulated laser built in the CAP transmitter at the transmitting end, increase the eye opening of the modulated signal, and improve the system performance. Transmission performance; moreover, higher rate information transmission of the system can be realized; at the same time, the structure of the existing communication system is not changed, the cost is low, and it is easy to implement.

The third embodiment of the present invention relates to an optical communication system, specifically as shown in FIG. 4 , including: a receiving end of CAP communication and a transmitting end of optical communication in the first embodiment.

It is not difficult to find that this embodiment is a system embodiment corresponding to the first embodiment, and this embodiment can be implemented in cooperation with the first embodiment. The relevant technical details mentioned in the first embodiment are still valid in this embodiment, and will not be repeated here in order to reduce repetition. Correspondingly, the relevant technical details mentioned in this implementation manner can also be applied in the first implementation manner.

The fourth embodiment of the present invention relates to an optical communication system, as shown in FIG. 5 , including: a transmitting end of CAP communication and a receiving end of optical communication in the second embodiment.

It is not difficult to find that this embodiment is a system embodiment corresponding to the second embodiment, and this embodiment can be implemented in cooperation with the second embodiment. The relevant technical details mentioned in the second embodiment are still valid in this embodiment, and will not be repeated here to reduce repetition. Correspondingly, the relevant technical details mentioned in this embodiment mode can also be applied in the second embodiment mode.

The fifth embodiment of the present invention relates to a data sending method for optical communication, which includes the following steps: the transmitting end performs asymmetric filtering on the transmitted signal and sends it out.

It is not difficult to find that this embodiment is a method example corresponding to the first embodiment, and this embodiment can be implemented in cooperation with the first embodiment. The relevant technical details mentioned in the first embodiment are still valid in this embodiment, and will not be repeated here in order to reduce repetition. Correspondingly, the relevant technical details mentioned in this implementation manner can also be applied in the first implementation manner.

The sixth embodiment of the present invention relates to a data receiving method for optical communication, including the following steps:

In step 601, the receiving end performs asymmetric filtering on the signal sent by the sending end.

Step 602, directly detect the asymmetrically filtered signal and convert it into an electrical signal.

Step 603, decoding and demodulating the electrical signal.

It is not difficult to find that this embodiment is a method example corresponding to the second embodiment, and this embodiment can be implemented in cooperation with the second embodiment. The relevant technical details mentioned in the second embodiment are still valid in this embodiment, and will not be repeated here to reduce repetition. Correspondingly, the relevant technical details mentioned in this embodiment mode can also be applied in the second embodiment mode.

Those of ordinary skill in the art can understand that the above-mentioned embodiments are specific examples for realizing the present invention, and in practical applications, various changes can be made to it in form and details without departing from the spirit and spirit of the present invention. scope.

Claims (9)

1. a transmitting terminal for optical communication, is characterized in that, comprises: CAP transmitter and optical filter; Transmitting of described CAP transmitter sends to receiving terminal after described optical filter carries out asymmetric filtering.

2. the transmitting terminal of optical communication according to claim 1, is characterized in that, the number of described CAP transmitter and described optical filter is N, and described N is natural number; Described CAP transmitter and described optical filter are corresponding one by one;

Described transmitting terminal also comprises wavelength division multiplexer;

Described in each, CAP transmitter carries out to the signal of respective user that no-load wave amplitude is modulated mutually and multistage coding; After optical filter carries out asymmetric filtering to transmitting of corresponding CAP transmitter described in each, be sent to described wavelength division multiplexer; Described wavelength division multiplexer merges N filtered signal, and sends to receiving terminal by optical fiber.

3. the transmitting terminal of optical communication according to claim 1, is characterized in that, described optical filter is band pass filter or band stop filter.

4. a receiving terminal for optical communication, is characterized in that, comprises: optical filter, photo-detector and decoding demodulator;

The signal of described optical filter spontaneous emission in the future end carries out direct detection by described photo-detector to filtered light signal, and is converted to the signal of telecommunication after carrying out asymmetric filtering; Described decoding demodulator is to the demodulation of decoding of the described signal of telecommunication.

5. the receiving terminal of optical communication according to claim 4, is characterized in that, the number of described optical filter, described photo-detector and described decoding demodulator is N, and described N is natural number; Described optical filter, described photo-detector and described decoding demodulator are corresponding one by one;

Described receiving terminal also comprises: demodulation multiplexer;

Described demodulation multiplexer carries out demultiplexing to the combined signal receiving; After optical filter carries out asymmetric filtering to described demultiplexed signal described in each, be sent to corresponding photo-detector.

6. the receiving terminal of optical communication according to claim 4, is characterized in that, described optical filter is band pass filter or band stop filter.

7. an optical communication system, is characterized in that, comprises: the transmitting terminal of the optical communication as described in claims 1 to 3;

Or, the receiving terminal of the optical communication as described in claim 4 to 5.

8. a data transmission method for uplink for optical communication, is characterized in that, comprises following steps:

By transmitting terminal, the signal of transmitting is carried out sending after asymmetric filtering.

9. a data receive method for optical communication, is characterized in that, comprises following steps:

Signal transmitting terminal being sent by receiving terminal carries out asymmetric filtering;

Asymmetric filtered signal is carried out to direct detection, and be converted to the signal of telecommunication;

To the demodulation of decoding of the described signal of telecommunication.