CN105827320A - Transmission device of ultra-narrow bandwidth spectrum segmentation incoherent light source based on FFP filter and FFP-SOA applied to WDM-PON - Google Patents

Abstract

The invention discloses a transmission device for ultra-narrowband spectrum segmentation incoherent light sources based on FFP filters and FFP-SOA in WDM-PON, including a central station, transmission optical fibers, remote nodes and optical network terminals. The remote node is connected to the central station through a transmission optical fiber, the optical network terminal is connected to the remote node, and the central station includes a sequentially connected wide-spectrum incoherent light source, FFP filter, FFP-SOA, and a first-stage arrayed waveguide grating , a plurality of optical modulators and a second-level arrayed waveguide grating, and two ends of the plurality of optical modulators are respectively connected to the first-level arrayed waveguide grating and the second-level arrayed waveguide grating. The ultra-narrow-band spectrum-sliced incoherent light source amplified by FFP-SOA can realize the compression of the intensity noise of the multi-channel spectrum-sliced incoherent light source, effectively suppress the influence of dispersion, and is suitable for long-distance dense wavelength division multiplexing optical passive network (DWDM) ‑PON) communication system.

Description

A transmission device for ultra-narrowband spectrum-sliced incoherent light source based on FFP filter and FFP-SOA in WDM-PON

technical field

The invention belongs to the technical field of communication, in particular to a transmission device for an ultra-narrowband spectrum-sliced incoherent light source based on an FFP filter and an FFP-SOA in WDM-PON.

Background technique

Passive Optical Network (PON) is considered to be the most critical technology to solve the "last mile" in the access network, and plays an important role in the realization of FTTX. "Passive" means that there are no active devices in the optical distribution node (ODN), only composed of optical passive devices such as couplers, wavelength division multiplexer/demultiplexers, and circulators, which greatly reduces the cost of management and maintenance.

According to signal distribution, PON can be divided into power split passive optical network (PSPON) and wavelength division multiplexing passive optical network (WDM-PON). APON, BPON, EPON, and GPON all belong to PSPON. PSPON adopts star coupler for branching, and uplink and downlink transmission adopt TDMA/TDM mode to realize channel bandwidth sharing. The optical splitter distributes the signal sent by OLT to each Optical Network Unit (ONU). WDM-PON makes full use of wavelength division multiplexing technology, and separates signal lights of different wavelengths through wavelength division multiplexing demultiplexers (such as arrayed waveguide gratings AWG), and each wavelength can modulate signals independently to achieve complete meaning. Exclusive bandwidth on the Internet.

Although PSPON is relatively mature, especially EPON and GPON have been deployed on a large scale in North America and Japan, there are still key problems to be solved in PSPON, such as fast bit synchronization, dynamic bandwidth allocation, baseline drift, ONU ranging and delay Compensation, design of burst mode optical transceiver module, etc. Although some problems have been solved, but the cost is higher. WDM-PON, on the other hand, uses the wavelength as the identifier of the user terminal, and uses wavelength division multiplexing technology to provide a wider working bandwidth and realize symmetrical broadband access. In addition, it can also avoid many technical difficulties such as ONU ranging and fast bit synchronization in time division multiple access technology, and has obvious advantages in system upgrade performance and other aspects.

However, as the access distance of the WDM-PON system increases, the fiber dispersion and the dispersion effect of the arrayed waveguide will lead to an increase in the system bit error rate. At present, it is considered that the method that can better solve the dispersion effect is the dispersion compensation fiber grating, and the dispersion characteristics are improved by adding a compensation fiber grating to the AWG. The essence of dispersion compensation is to compress and compensate the pulse broadening caused by the second phase shift of frequency.

Contents of the invention

In order to solve the above technical problems, the present invention provides a transmission device for incoherent light sources based on FFP filters and FFP-SOA ultra-narrowband spectrum segmentation in WDM-PON, which can effectively suppress the influence of intensity noise and is suitable for long-distance DWDM -PON communication system.

The present invention adopts the following technical solutions: a transmission device for ultra-narrowband spectrum segmentation incoherent light source based on FFP filter and FFP-SOA in WDM-PON, including central office (CO), transmission optical fiber, remote node (RN) and optical network terminal (ONU), the remote node is connected to the central station through a transmission fiber, the optical network terminal is connected to the remote node, and the central station includes a wide Spectrum incoherent light source, FFP filter (Fabry-Perot filter), FFP-SOA (Fabry-Perot semiconductor optical amplifier), first-stage arrayed waveguide grating (AWG1), multiple optical modulators and The second-level arrayed waveguide grating (AWG2), the two ends of the multiple optical modulators are respectively connected to the first-level arrayed waveguide grating and the second-level arrayed waveguide grating, where the FFP filter is used to cut the wide-spectrum incoherent light source signal , generate and output multi-wavelength ultra-narrow-band spectrum-sliced incoherent light sources, FFP-SOA has low saturation power, needs to work in the saturated work area, and is used to nonlinearly amplify ultra-narrow-band spectrum-sliced incoherent light sources of different wavelengths, and simultaneously utilize The nonlinear amplification characteristic compresses the intensity noise of the multi-wavelength ultra-narrow-band spectrum-sliced incoherent light source, and multiple optical modulators are used to modulate the signal to the noise-suppressed ultra-narrow-band spectrum-sliced incoherent light source of each wavelength. Sensitive electroabsorption optical modulator to enhance 3-dB system transmission performance. Use the FFP filter with ultra-narrow bandwidth to split the wide-spectrum incoherent light source to obtain multi-wavelength ultra-narrow-band spectrum-sliced incoherent light source signals. Amplify and use the nonlinear amplification characteristics to compress the intensity noise in the multi-wavelength ultra-narrow-band spectrum-slicing incoherent light source, and then distribute the different light wavelengths of the ultra-narrow-band spectrum-slicing incoherent light source to corresponding In the wavelength channel, modulate and load the data information of each channel, and then realize the wavelength division multiplexing through the second-level arrayed waveguide grating (AWG2), and then transmit it to the remote node RN by the transmission fiber, and realize the wavelength division multiplexing at the remote node , and finally distribute the data to the optical network terminal ONU. The optical network terminal implements demodulation of downlink data and transmission of uplink data.

The remote node includes a third-level arrayed waveguide grating (AWG3) or thin-film filter, which is connected to the central station through a transmission fiber, and the optical signal sent from the central station CO is decomposed and multiplexed by the AWG3 wave, and then output to the distributed optical communication lines.

The optical network terminal includes a plurality of optical receivers connected to remote nodes. The optical receiver is connected to a third demultiplexer/wavelength division multiplexer (eg AWG3). The optical receiver includes a photodiode, a first bandpass filter and a decoder.

The wide-spectrum incoherent light source is realized by a high-power erbium-doped fiber amplifier, a light-emitting diode, a superluminescent light-emitting diode or a Fabry-Perot laser diode spectrum light source.

The channel spacing of the FFP filter and the FFP-SOA needs to be consistent with the communication channel spacing of the WDM-PON system.

The FFP-SOA works in a saturated working area, and utilizes the nonlinear amplification characteristic of the saturated working area to achieve the purpose of compressing the intensity noise in the light source.

The temperature of the FFP filter and FFP-SOA is controlled by TEC.

The plurality of light modulators adopt an on-off keying modulation method which is better resistant to intensity noise.

The optical modulator is provided with a pre-error correction code, and the optical network terminal is provided with a pre-error correction code to enhance the noise resistance of the system.

The FFP filter (Fabry-Perot filter) in the present invention is an ultra-narrowband bandpass filter, and a Gaussian filter or a fiber grating filter with a Lorentz shape can also be used.

In the present invention, pre-error correction coding can be used at the transmitting end, and pre-error correction decoding can be used after the self-feedback threshold judgment circuit at the receiving end to enhance the noise resistance of the system.

The advantages of the present invention are: the ultra-narrowband spectrum-sliced incoherent light source of the present invention utilizes FFP filter to pair erbium doped fiber amplifier (Erbium Doped Fiber Broad-spectrum amplified spontaneous emission (Amplified Spontaneous) light source (Amplified Spontaneous) produced by Amplifier, EDFA Emission, ASE) is filtered and amplified by FFP-SOA, and its linewidth is less than 700MHz. The ultra-narrow-band spectrum-sliced incoherent light source after FFP-SOA amplification can realize multi-channel spectrum-sliced incoherent light source intensity noise Compression, effectively suppress the influence of dispersion, suitable for long-distance dense wavelength division multiplexing optical passive network (DWDM-PON) communication system.

Description of drawings

Figure 1 is a WDM-PON view of an ultra-narrowband spectrum-sliced incoherent light source based on FFP filters and FFP-SOA;

Figure 2 is the relative intensity noise spectrogram before and after the FFP-SOA using the ultra-narrowband spectrum segmentation light source in the WDM-PON system;

Fig. 3 is a schematic diagram of the intensity noise in the compressed light source using FFP-SOA working in the saturated working region;

Figure 4 is a diagram of the relationship between the bit error rate and the transmission distance of the 25-Gb/s OOK signal transmitted in the 1542nm wavelength channel in the WDM-PON system using the FFP filter and the FFP-SOA;

Figure 5 shows the bit error rate performance of different wavelength channels in the back-to-back system in a WDM-PON system based on FFP filters and FFP-SOA ultra-narrowband spectrum-sliced incoherent light sources.

detailed description

In order to deepen the understanding of the present invention, the present invention will be further described below in conjunction with the embodiments and accompanying drawings. The embodiments are only used to explain the present invention and do not constitute a limitation to the protection scope of the present invention.

As shown in Figure 1, a transmission device for ultra-narrowband spectrum-slicing incoherent light sources based on FFP filters and FFP-SOA in WDM-PON, including a central office (CO), transmission optical fiber (select single-mode optical fiber ), the remote node (RN) and the optical network terminal (ONU), the remote node is connected to the central station through the transmission fiber, and the optical network terminal is connected to the remote node.

The central station includes a wide-spectrum incoherent light source BLS for incident downlink signals. In this embodiment, a high-power erbium-doped fiber amplifier is selected to generate a spontaneously emitted large divergent light source; Light-passing filter, FFP filter (Fabry-Perot filter) is selected in this embodiment; it is used to non-linearly amplify the ultra-narrow-band spectrum of different wavelengths and incoherent light source signals and compress them by using the non-linear amplification characteristics FFP-SOA (Fabry-Perot Semiconductor Optical Amplifier) of intensity noise in light sources of different wavelengths; the first demultiplexing coupling device that separates ultra-narrowband spectrally segmented incoherent light sources of different wavelengths into corresponding channels, in this embodiment The first-stage arrayed waveguide grating (AWG1) is selected; multiple optical modulators are used to modulate the signal to an ultra-narrow-band spectrum-sliced incoherent light source at each wavelength with noise suppression, which can be achieved by polarization-insensitive electro-absorption optical modulators To enhance the signal-to-noise ratio and enhance the transmission performance of the 3-dB system, the signal has passed the pre-error correction code before optical modulation; and the second wavelength division multiplexer that couples multiple downlink signals is selected in this embodiment The second-stage arrayed waveguide grating (AWG2). Among them, the channel spacing of the FFP filter and the FFP-SOA should be consistent with the communication channel spacing of the WDM-PON system. Intensity noise suppression of light sources with different wavelengths in the PON system. The ultra-narrow-band spectrum-sliced incoherent light source signals of different wavelengths obtained by FFP filter segmentation have a large intensity noise in the low-frequency region, and the noise is the largest near the DC region, and it is different from the light source. The linewidth is inversely proportional (relative noise intensity = 1/linewidth of the ultra-narrowband spectrum-sliced incoherent light source).

The remote node includes a third wavelength division multiplexer/demultiplexer for wavelength division multiplexing/demultiplexing, which is connected to the central station through a transmission fiber; in this embodiment, the third-level arrayed waveguide grating (AWG3) is selected, After the optical signal sent from the central station CO is decomposed and multiplexed by AWG3, it is output to the distributed optical communication line.

The optical network terminal includes a plurality of optical receivers connected to remote nodes. The optical receiver is connected to the third wavelength division multiplexer/demultiplexer, and AWG3 is selected in this embodiment. The optical receiver contains a photodiode, a first bandpass filter and a decoder.

As shown in Figure 2, the relative intensity noise spectrograms before and after the ultra-narrowband spectrum-sliced light source in the WDM-PON system is compared with that of the FFP-SOA. The spectrum-sliced incoherent light source with ultra-narrowband 700-MHz linewidth is mainly concentrated in the low frequency region. Using the FFP-SOA working in the saturation region can effectively reduce the intensity noise, and the relative intensity noise is reduced from -90dB/Hz to -118dB/Hz (near DC range).

As shown in Figure 3, the principle of using the FFP-SOA operating in the saturation region to compress the intensity noise in the light source: the FFP-SOA operating in the saturation region has nonlinear amplification characteristics, that is, the amplification factor of the low-power input signal is much greater than that of the high-power The magnification of the input signal, using this feature can compress the intensity noise in the light source and obtain a relatively stable light source signal.

As shown in Figure 4, in a WDM-PON system, when a channel located at 1542nm transmits a 25Gb/s signal, after using a saturated optical amplifier to compress the intensity noise in the light source, the relationship between the bit error rate of the signal and the signal transmission distance.

As shown in Figure 5, in the WDM-PON system, in the back-to-back transmission, the bit error rate of the 25Gb/s OOK signal transmitted by different wavelength channels (without pre-error correction decoding).

Claims (10)

1. null1. the transmitting device of the ultra-narrow band spectrum segmentation incoherent light source based on FFP wave filter and FFP-SOA in WDM-PON，It is characterized in that，Including central station，Transmission Fibers，Distant-end node and ONT Optical Network Terminal，Described distant-end node is connected with central station by Transmission Fibers，Described ONT Optical Network Terminal is connected with distant-end node，Described central station includes the wide range incoherent light source being sequentially connected with、FFP wave filter、FFP-SOA、First order array waveguide grating、Multiple photomodulators and second level array waveguide grating，The two ends of the plurality of photomodulator are connected with first order array waveguide grating and second level array waveguide grating respectively，Utilize FFP wave filter that wide range incoherent light source cutting is obtained multi-wavelength ultra-narrow band spectrum segmentation incoherent light source，Followed by working in the FFP-SOA of saturation to compress the intensity noise of multi-wavelength ultra-narrow band spectrum segmentation incoherent light source，Pass through first order array waveguide grating branch afterwards and load each circuit-switched data information，Wavelength-division multiplex is realized again by second level array waveguide grating，Then transmitted to distant-end node by Transmission Fibers，Wave Decomposition multiplexing is realized at distant-end node，Finally data are distributed to ONT Optical Network Terminal.
2. The transmitting device of a kind of ultra-narrow band spectrum segmentation incoherent light source based on FFP wave filter and FFP-SOA in WDM-PON the most according to claim 1, it is characterised in that described distant-end node includes third level array waveguide grating or film filter.
3. The transmitting device of a kind of ultra-narrow band spectrum segmentation incoherent light source based on FFP wave filter and FFP-SOA in WDM-PON the most according to claim 1, it is characterised in that described ONT Optical Network Terminal includes the multiple optical receivers being connected with distant-end node.
4. The transmitting device of a kind of ultra-narrow band spectrum segmentation incoherent light source based on FFP wave filter and FFP-SOA in WDM-PON the most according to claim 3, it is characterised in that described optical receiver comprises photodiode, the first band filter and decoder.
5. The transmitting device of a kind of ultra-narrow band spectrum segmentation incoherent light source based on FFP wave filter and FFP-SOA in WDM-PON the most according to claim 1, it is characterized in that, described wide range incoherent light source is realized by high power erbium-doped fiber amplifier, light emitting diode, super-radiance light emitting diode or fabry-Perot laser diode spectroscopic light source.
6. The transmitting device of a kind of ultra-narrow band spectrum segmentation incoherent light source based on FFP wave filter and FFP-SOA in WDM-PON the most according to claim 1, it is characterized in that, described FFP wave filter needs all with the channel spacing of FFP-SOA and the communication channel interval of WDM-PON system is consistent.
7. The transmitting device of a kind of ultra-narrow band spectrum segmentation incoherent light source based on FFP wave filter and FFP-SOA in WDM-PON the most according to claim 1, it is characterized in that, described FFP-SOA works in saturation operation region, utilizes the non-linear amplification characteristic of saturation operation region to reach to compress the purpose of intensity noise in light source.
8. The transmitting device of a kind of ultra-narrow band spectrum segmentation incoherent light source based on FFP wave filter and FFP-SOA in WDM-PON the most according to claim 1, it is characterised in that the temperature of described FFP wave filter and FFP-SOA is controlled by TEC.
9. The transmitting device of a kind of ultra-narrow band spectrum segmentation incoherent light source based on FFP wave filter and FFP-SOA in WDM-PON the most according to claim 1, it is characterized in that, the plurality of photomodulator uses the on-off keying modulation system having resistance to intensity noise.
10. The transmitting device of a kind of ultra-narrow band spectrum segmentation incoherent light source based on FFP wave filter and FFP-SOA in WDM-PON the most according to claim 1, it is characterized in that, being provided with preposition Error Correction of Coding before described photomodulator, ONT Optical Network Terminal is provided with preposition error correction decoding.