WO2012120172A1 - Method and apparatus for a bidirectional optical link comprising simultaneous amplitude and phase modulation by means of an integrated semiconductor device that is wavelength agnostic - Google Patents

Abstract

The invention relates to a method and optical apparatus for a bidirectional optical link that uses a simple integrated semiconductor, which is wavelength agnostic, to achieve the transmission of signals by means of simultaneous amplitude and phase modulation of the light.

Description

Method and apparatus for bidirectional optical link with simultaneous amplitude and phase modulation using an integrated semiconductor device and wavelength agnostic. [Corrected according to Rule 26 17.05.2012] Technical Sector

 The present invention relates to an optical method and apparatus for a bidirectional optical link using a simple, integrated and wavelength semiconductor device to achieve signal transmission by simultaneous modulation of light in phase and in amplitude.

[Corrected according to Rule 26 17.05.2012] State of the art

Fiber optic communications are one of the techniques to allow customers to offer broadband services to customers that may be located in dispersed geographic areas. Optical fiber is used as a means of transmission because it offers several advantages compared to copper cables, such as the traditional twisted pair. Fiber-up-the-X (FTTx) is a technology (X can be the sidewalk, node, building, home or other) that has been studied extensively throughout the world, to offer high bandwidth to users and offer convergence between radio and cable technologies.

Although amplification means may be included in the transmission link, the access networks are usually transparent to the data signal, since it remains passive without elements of electrical-optical or electrical-optical conversion. These types of passive optical networks are beneficial for operators, since capital and operating costs are minimized. The difference with point-to-point links can be found in the inclusion of passive distribution elements, such as wavelength division multiplexers or temporal multiplexers (WDM, TDM) or a combination of both. These devices allow multiplexing packets from a group of clients to a single network, which decreases the cost per user of the network. Unlike TDM networks, based on a system of specific time assignments for data transmission, the WDM wavelength multiplexing technique does not require a specific design for the customer's local equipment, if it is capable of operating at a wide range of optical wavelengths thanks to current development of low-cost modulators and amplifiers, independent of wavelength. In accordance with this principle of agnosticism at the received wavelength, a unique design can be used for several clients (ONU favoring the mass deployment of these devices.

The light sources in the access networks are normally centralized in the optical line terminal (OLT) or in the ONU, depending on the exact realization of the equipment of the client's facilities. For the first case, the UN aims to provide a function as a remote modulator for the transmission of user data from the network to the operator, henceforth, the upstream transmission. The light that is required as optical current support can be taken directly from the data sent from the OLT, which refers to the downstream transmission, or by an auxiliary carrier signal transmitted by the OLT, together with the transmission downstream. Since a full-duplex transmission is desired, a downstream will be present during upstream modulation, so that, in principle, no optical source is required to the ONU. Finally, the techniques for improving upstream transmission can be applied, whose objective is the adjustment of the modulation signal of the downstream detected signal that is still present in the optical carrier. Examples can be found in the prior art for intensity modulated by simple-and above signals [US2007 / 0183788A1], and also for phase modulation signals, although the use of bulky components in the ONU [Chow08].
For these mentioned approaches of the injection of light to the seeds of the upstream transmitter, the client's local equipment is then, in principle, of a reflective design and preferably uses amplifiers modulated with small form factor. For some specific applications that include, for example, consistent detection of downstream, a local light source is mandatory and can be reused as an optical medium for upstream transmission.

Promising candidates for the aforementioned low-cost modulators with small form factor are the SOA optical (R) semiconductor amplifier (reflective), the electro-absorption (R) EAM (reflective) modulator or integrated versions of them in the form of a SOA / (R) EAM or similar derivatives. In traditional approaches, SOA normally acts solely as an amplifier to also overcome EAM losses.

Within the investigation, several UN designs and modulation formats for downstream and upstream have been proposed. In principle, most of them focused on simple realizations for the UN subsystems, and through photonic integration they were not available and is not expected to be available in the following years. However, progress has been made and it is expected that the complexity soon added that allows for additional important functionality will come at only marginal cost.

This allows, for example the introduction of advanced modulation formats, however, the requirements of low power consumption and small form factor have yet to be met. Unfortunately, efficient, but complex, modulation formats, such as (higher order), quadrature amplitude modulation (QAM) that are used in the long-distance transmission systems of major modulator networks require complex and bulky ones, such as Mach-Zehnder nested modulators or similar structures [US2009324247A1].

These modulation formats encode the data, not only in the intensity of the optical signal - as it is commonly used in low-cost applications - but also in the optical phase. This allows first to increase the data rate since the data can be encoded in (several) tributaries of the advanced modulation format, and secondly, the spectral width of the data transmission signal can be kept compact, so which is beneficial for the transmission over long fiber extends. Alternatively, instead of modulating at the same time the optical signal in the intensity and phase, it is often desirable to modulate different instances of the optical signal with different modulation formats, in order to differentiate the parts of the generated signal, as per example the label and payload of a data packet. This allows for easy removal of the different modulation pieces from the data packet, for sample extraction from the packet label in all optical, tag switching networks. In these cases, the tag can be encoded at a lower speed and possibly to a different subcarrier, to facilitate the extraction and processing of header data. Note that the tag does not necessarily have to be separated from the load data using, for example, different instances of time, but it can also be coded simultaneously using an advanced QAM modulation format such as, for example, the payload It is encoded by modulation of the signal strength and the package label can be encoded by the simultaneous modulation of the phase of the optical signal itself, although at a lower data rate. Some previous work describes the interest of this type of simultaneous intensity and modulation of the payload information phase and the [Blumenthal00] label. This proposal provides a simple method and devices for generating the described signals.

Although progress has been made for the application of modulators required in terms of achieving smaller form factors than conventional Lithium Niobate devices, there are still significant losses introduced into the corresponding transmission subsystem. In addition, imperfections, such as the remaining polarization dependence remain. These reasons, and also the higher cost factor, are restricting the techniques of entering optical access requests.

On the contrary, the application of advanced modulation formats for well-studied low-cost and wavelength-agnostic modulators based on SOA and EAM can lead to a beneficial solution for high data bandwidths and / or additional functionality, such as the transmission of several channels, without adding the extra phase of frequency modulators to the cost-sensitive ONU. prior art has already demonstrated the generation of phase modulation based on laser amplifiers [WO9007141A1] or EAM interferometric structures based on [US2008 / 074722A1]. In addition, the possibility of introducing frequency modulation with light sources has been demonstrated [EP1624594A2], and a possible extension for the application of advanced modulation formats with light sources and external modulators has been demonstrated thus [US2007 / 0127931A1], Both systems are based on integrating semiconductor devices of small form factor - although not without color, in this case.

References

[US2007 / 0183788A1] “Feed-Forward Current Injection Circuits and Semiconductor Optical Amplifier Structures for Downstream Optical Signal Reuse Method”, B.W. Kim et al., US Patent US 2007/0183788 A1.

[Chow08] C. W. Chow, “Wavelength Remodulation Using DPSK Down-and-Upstream With High Extinction Ratio for 10-Gb / s DWDM-Passive Optical Networks,” IEEE Photonics Technology Letters, vol. 20, pp. 12-14, Jan. 2008.

[US2009324247A1] "Optical Modulator", N. Kikuchi, US Patent US 2009/0324247 A1.

[WO9007141A1] "Phase Modulation", J. Mellis, World Patent WO 90/07141 A1.

[US2008 / 074722A1] “Interferometric Operation of Electroabsorption Modulators”, I. Kang, US Patent US 2008/0074722 A1

[EP1624594A2] "Apparatus and method for optical frequency-shift-keying optical transmission", H. Kim, EU Patent EP 1 624 594 A2

[US2007 / 0127931A1] "Optical Transceiver Module", H. Kim, S.K. Kim, H.L. Lee, S.T. Hwang, US Patent US 2007/0127931 A1

[Blumenthal00] D.J. Blumenthal et al., "All-Optical Label Swapping Networks and Technologies", IEEE J. of Lightwave Technology, vol. 18, no. 12, pp 2058, Dec 2000.

[Corrected according to Rule 26 17.05.2012] Explanation of the invention

The invitation is related to a method to simultaneously perform multi-level modulation in the form of amplitude, phase or amplitude and key phase change (ASK, PSK), with the help of an integrated, colorless (reflective) modulator system that It is based on SOA and an EAM element. On the other hand, a method for remodulation of a (higher order) of the downstream QAM signal with the ASK + PSK signal upstream full-duplex QAM data transmission is provided.

Following the objectives, an optical transmission network of any type of network is suitable, consisting of:

- An OLT contains optical sources for the transmission of ASK or QAM signals or in the simplest case an optical continuous carrier towards the responsibility, and also the receivers for the reception of the data above several ONUs, transmitted in simultaneous ASK and modulation PSK;
- A fiber distribution plant known as the optical distribution network (ODN) of the present, which comprises fiber to connect several ONUs to the OLT. For the reason of multiplexing, it can also include one or more interconnection points for the transmission of data traffic from the OLT with the load back and forth. These relationship points between the different segments of the ODN are not specified;
- ONUs that make up the receivers for the downstream, which are designed in accordance with the modulation format chosen downstream, and a reflection reflector against the current that uses the intermediate incident signal or a local oscillator signal for water transmission above.

The ONU is the main objective of the present invention and has a technique of modulating an optical input signal of the intensity and phase. This is achieved through an integrated modulator consisting of at least one SOA and an EAM section, with which the signal is modulated in its optical phase and intensity, respectively.

Full-duplex transmission with the reuse of the optical signal that already carries intermediate data can be achieved by providing feedback of the output detector information for the upstream transmitter through an electronic light remodulation control (LCR) circuit . In this way, the phase modulation and intensity can be altered by the content of the additional information, whereby the phase is already present and / or modulation of the intensity of the downstream current is taken into account and compensated. Since the light from the incoming downstream signal is reused for upstream transmission, upstream of the transmitter is known as the remodulator (REM) in the subsequent sections.

On the other hand, a local oscillator can be used directly as a seed for REM, so no means of CSF are required. In this case, the optical light of the local oscillator can be used simultaneously for coherent detection of the downstream signal.

Two preferred embodiments of the UN are considered, which depend on the incorporation of a local oscillator into the UN. For the first preferred embodiment, no local oscillator is included and subsequent detection is carried out after a suitable demodulator (DEM) for the elimination and / or intensity modulation, while for the second preferred embodiment, an oscillator Local is also included for the current signal, also providing a requirement for consistent detection. Both embodiments, especially the first one, can also be operated in half-duplex mode to simplify the ONU design, for example, the LCR.

[Corrected according to Rule 26 17.05.2012] Brief description of the figures

A more detailed description of the present invention will be given by taking reference to the accompanying drawings that show examples for the realization of the present invention, which allows to provide an illustrative description of the preferred embodiments.

It was emphasized that the drawings always contain all the essential information that is believed to be most relevant to the understanding of the principles of the present invention. In addition, it is not intended to show the result of unnecessarily detailed structures of the invention, for ease of understanding. In this way, non-essential elements have been omitted from some of the drawings. For cases where no example is given, it is left to those who are experts in the art, how the fundamental structures represented in the drawings can be observed in practice.

Fig. 1 represents the optical network with a flow of downstream data that is modulated in its intensity and / or phase, and of rise data modulated in its intensity and phase, in which context the UN in the client's facilities includes a transmitter simple upstream of said upstream modulation format, in accordance with the present invention.

Fig. 2 depicts a preferred embodiment of the ONU for bidirectional transmission of optical networks with a low current intensity and / or phase modulation formats, including an integrated reflective modulator such as upstream transmitter and CSF media, according to the invention preferred present first embodiment.

Fig. 3 depicts other preferred embodiments of the UN REM, which is used as a previous phase transmitter and / or intensity modulation, in accordance with the present invention.

Fig. 4 depicts the main scheme of electrical conduction of the REM, which is performed in the upstream transmitter, and the functionality of the LCR, in accordance with the present invention.

Fig. 5 represents a ONU for bidirectional transmission of optical networks with a low current intensity and / or phase modulation formats, including an integrated REM as a current transmitter and a local light source, according to the second preferred embodiment of the invention.

Fig. 6 depicts potential applications including the integrated optical transmitter for amplitude phase and modulation, in accordance with the present invention.

[Corrected according to Rule 26 17.05.2012] Detailed description of the invention

Before an explanation of the present invention is given, it should be noted that the invention is not limited in its application to the data indicated in the following discussion or the examples provided. The present invention can be carried out in several incarnations. It will be understood that certain characteristics that are described in the context of different incarnations, can also be provided for a specific specific embodiment. In turn, certain features that are described in the context of a single incarnation can also be provided for any suitable embodiment of others included in the description of the invention.

The terms "comprises", "understanding", "includes", "included", and "having" are supposed to be understood as "including but not limited to", while the term "composed of" has the same meaning as " as and is limited to ". The term ", which consists essentially of" means that the structure may include additional pieces, but only if these additional pieces do not disturb or alter the basic characteristics and novel of the requested structure. On the other hand, the singular form "a", "a", and "the" also include plural references unless otherwise dictated by the context.

[Corrected according to Rule 26 17.05.2012] Detailed description of the method and apparatus

A new ONU is introduced, based on a solution with integrated semiconductor devices for the modulation of an optical signal in its optical phase and intensity while receiving a similar signal that is also used as an optical seed at the same time. This method allows a significant increase in the data rate for bidirectional transmission between the OLT and the ONU in an optical network, while maintaining the possibility of an integrated design without bulky and expensive components.

Taking into account the preferred embodiment of the invention, the modifications are only necessary in the ONU and do not disturb the fiber distribution plant or the OLT (in addition to the choice of the specific phase and / or intensity modulation for the transmitter and the receiver from the bottom up), or other preferred embodiments of the invention.

In the discussion of the figures in this document, a similar number refers to similar parts. The drawings also do not have to be to scale.

Referring to Figure 1, which illustrates the optical network architecture of 100, in which context the present invention is inserted.

The optical network (ON) 100 comprises an OLT 110, a ONU 130 that is connected through ODN 120. In its simplest form, ODN 120 consists essentially of a bidirectional relationship between OLT 140 110 and ONU 130. This link can be established by a single optical fiber. In general, ODN 120 also incorporates WDM and TDM techniques as described above.

The signals from OLT 110 to ONU 130 refers to downstream signals, while signals from ONU 130 to OLT 110 refers to upstream signals.

The OLT 110 includes at least one optical source of the ON 100 and an optical phase and / or intensity modulator, which is used for coating the optical carrier with the data below. The characteristics of this modulator conform to the design of the DEM within UN 130. To establish the bidirectional data transmission along fiber link 140, the downstream and upstream signals are divided / merged into OLT 110 in / from two unidirectional data streams. While the intermediate is derived from the optical transmitter containing the modulator, he said, the current is fed to the OLT 110 optical receiver. The functionality of the cleavage and fusion of the data streams can be done with an appropriate optical device, such as an optical circulator. Note that two wavelengths can also be used, in principle, to transport the data down and upstream, which allows an optical filter to be placed instead of the circulation pump. The optical receiver of the OLT 110 includes more photodetectors such as PIN diodes or photo avalanche diodes.

Depending on the requirements within EN 100, the OLT 110 may also include other components such as optical amplifiers, dispersion compensation means, WDM optical multiplexer / demultiplexer and electronic signal conditioning. These elements are placed properly and are intended to ensure optimal performance, both for the transmission of data streams. In addition, the OLT 110 is capable of performing higher layer functionalities and is interconnected to an operator interface according to modern telecommunications standards.

The OLT 110 and also the fiber infrastructure of the ON 100 can be shared among several operators, which are intended to deliver different types of services to customers. The UN 130 then has to be able to switch between the different operators in an appropriate manner, to activate this multi-operability function in the ON 100. This can be achieved by simultaneously using the different data channels within the below- above and for different operators. He said the data channels what can be the modulation of different tributaries such as phase or intensity modulation.

The UN 130, housed in the client's premises and, preferably, but not essentially identical for all network users, is responsible for downstream reception and upload data transmission and is now discussed in more detail in its Preferred embodiments of the invention.

Referring to Figure 2, which illustrates a ONU 200 for bidirectional transmission of optical networks with a low current intensity and / or phase modulation formats, which includes an integrated transmitter such as upstream REM and LRC media , in accordance with the first preferred embodiment of the present invention.

ONU 200 is connected to ODN 120 of ON 100 through line 201, through which 202 is received downstream and upstream of 206 is transmitted.

An optical power splitter 210, here is also known as a hitch, with a cutting force ratio there are no more specifications divide the 202 below into two signals of 203 and 204. While the first portion 203 is transmitted to the DEM 220 with the In order to detect below, the second part 204 is used as a seed for the REM 250 optics.

The DEM 220 consists of the functionality necessary to demodulate the chosen downstream modulation format. This may include, for example, delay interferometers or optical hybrids to convert the information that is encoded in the optic phase in intensity modulation. This is not the purpose of this patent. Previous inventions already describe possible implementations in detail. The DEM 220 is directly coupled to a set of 230 photo detectors, which contains at least one photo detector. The interconnection between the 220 German frames and the set of 230 photo detectors is not specified, but it can be, in principle, a fiber optic connection in the case of a fully integrated design only a small fragment of the waveguide or direct butt coupling in the case of micro-optics. The electrical signals derived from the photo detection 231, which contains at least one signal, is fed to the RX 240 electrical receiver. The RX 240 can be equipped with electrical means for amplification and filtering, processing of electrical signals and other functionalities that They can support optical transmission, as well as higher layer functionalities. The electrical user interface 241 for the RX 240 is designed according to a suitable telecommunications standard.

The REM 250 is essentially composed of an SOA 251 and an EAM 252. In its preferred embodiment, the REM 250 is of the reflexive type and also contains a very reflective facet 253 in the final aspect of the EAM 252. Thus, the light The 204 seed incident is reflected back to the bidirectional port 254 of REM 250, where 205 seeds appear as a modulation that is retransmitted through power splitter 210 to output 201 of UN 200.

The electrical conduction signals of 264 and 263 of the SOA 251 and EAM 252, respectively, are delivered to the electrical interfaces 255 and 256 of the REM 250 by the electrical transmitter (TX) 260. The TX 260 contains the electrical conduction circuits of the SOA 251 and EAM 252, including the means of polarization and electrical amplification, electrical filtering, as well as the processing of electronic signals and greater layer functionality, in accordance with the requirements for data transmission in EN 100.

The SOA 251 is responsible for the optical phase or amplitude modulation of the sowing signal 204 and traces of the information of a first electrical data upload channel in the optical signal, the EAM 252 is the encoding of a second data channel of the intensity of the optical seed 204. The conduction procedure of SOA 251 and EAM 252 is considered as ideal for this description of UN 200 and will be explained later.

As is the case with the electric receiver, the electric user interface 261 for the TX 260 is designed according to a suitable telecommunications standard.

Since the optical seed 204 of the REM 250 already contains some optical phase and / or intensity modulation that derives from the descent 202, an LCR 262 is included in the TX 260 to improve the transmission performance of the current 206 in terms of combating the modulation acting downstream of the optical seed 204. An interconnection between the 242 RX 240 and 262 of the LCR exists to send data about the current modulation to the electrical conduction circuits of the TX 260.

Due to its complexity, the principle of operation of LCR 262 is explained later in a separate section. However, for understanding, it will be understood that the modulation of electrical signals 264 and 263 of REM 250 are modified in such a way that the upstream output signal 206 corresponds to the upstream transmitted data that is received by the TX 260 through the user interface of 261, regardless of the down signal 202.

In the case that the half-duplex operation for downstream and upstream is chosen, which means that the descent is composed of continuous optical light for determined time intervals in a defined TDM scheme, the LCR 262 and the interconnection of 242 It may not be required.

For another case in which a second optical carrier signal is transmitted along with the subsequent ones 202 to be used as the seed (not modulated) for REM 250, the energy splitter 210 will be replaced by a suitable WDM separator, which may be example a Red / Blue band splitter in its simplest form.

The bit rate and the number of amplitude levels of the electrical signals of 263 and 264 are not necessarily identical. This provides greater agility in the design of the UN 200 in the event that the electro-optical bandwidth of SOA 251 and 252 EAM differ significantly. In such a scenario, the selection of an identical bit rate for both elements would result in the element with the lowest bandwidth that defines the possible bit rate. To avoid this limitation and improve data throughput, a modulation scheme, where the bit rate of the electrical conduction signal 263 for the EAM 252 is a multiple of the bit rate of the electrical conduction signal 264 of the SOA 251 can be used.

Referring to Figure 3, it illustrates other preferred embodiments 300 for the REM of the ONU 200, which is used as a current transmitter per phase and / or intensity modulation, in accordance with the present invention.

In the case of the application of a non-reflective remodulator (NREM) 310, an integrated chip consisting of an SOA section 313 and a 314 EAM section can be used together with a circulation pump 312. The optical bidirectional port 311 corresponds to the port 254 of REM 250 of UN 200, while electrical connections of 315 and 316 for SOA 313 and EAM 316, respectively, correspond to connections of 255 and 256.

Please note that the order of placement of SOA 313 and EAM 314 is not limited to that shown for NREM 310. Those skilled in the art are left to depart from the preferred modalities discussed in the present invention, to which The scope of the invention is not necessarily limited.

A better embodiment of a deployed version of REM 250 is the double amplifier remodulator (DAREM) 320, which consists mainly of a SOA 323 and 324 EAM and a circulator 322 like that of NREM 310. On the other hand, a second SOA 327 integrates with SOA 323 and 324 of the EAM, to provide a more powerful output signal to the bidirectional optical port 321.

In the same way as for NREM 310 of SOA 323 and 324 EAM, they are electrically connected to the ONU transmitter with connections 325 and 326, respectively. The electrical connection 328 of the additional SOA 327, which is also connected to the TX 260 of the ONU 200, can be biased with a constant electrical signal or driven by phase modulation such as the SOA 323.

Referring to Figure 4, it illustrates the main electrical conduction scheme of 400 of the REM and the functionality of the LCR, in accordance with the present invention.

For the explanation of the functionality of the TX 401, which acts as an electric current transmitter, reference is sometimes made to the elements of the UN 200 for ease of understanding.

Before explaining the driving regime for the action counter a downstream signal from the optical seed 453 of REM 450, the operating points for modulation of SOA 451 and 452 of the EAM are discussed.

The characteristics of SOA 451 when phase modulation is used are chosen so that a change in its company density leads to a significant change in its refractive index, while the induced change in its gain remains at an intermediate value, it is say, a great screech parameter. By operating SOA 451 in its saturation regime, a high phase ratio to the intensity of the modulation can be obtained. Intensity modulation can be achieved with SOA 451 by exploitation in the linear regime.

The EAM 452 is predisposed for intensity modulation, whereby the application of several levels of modulated intensity upstream indicates the operating point is preferably chosen in a linear regime, over time at the cost of some extra insertion loss and the light extinction reduction ratio so that the modulated optical seed 454.

As the element responsible for the REM 450 unit, TX 401 includes the driving circuit layout required to generate the DSOA DEAM 431 and 430 electrical conduction signals for SOA 451 and EAM 452, respectively, as well as the mentioned LCR 402. The REM 450 driving scheme is mainly determined by three aspects,

     - The transmission of the ST 410 data symbols, which are delivered by the user interface 261

     - The mitigation of the downstream symbols, which are already present in the optical medium, but is known due to downstream detection, so that they are available for TX 401 as SR 420 symbols through interconnection 242 to RX 240,

     - The suppression of interference between the phase and the intensity modulated data channels, which would occur due to the modulation of the residual intensity of the SOA when phase modulation is used

In addition to the LCR 402, TX 401 essentially includes a functional block 403 that performs greater functionalities of the layer and two electrical conductors 404 and 405 that include the means of processing the electrical signal and amplification, as well as polarization circuits.

The block of 403 acts as an interleaver, as well as for the flow of received data ST 410 and, consequently, divides the input data into the two currents of the P _T 412 and I _T 411 of the phase and intensity modulation, respectively .

With the two mentioned data sequences, the controllers 404 and 405 are fed, where they are suitably combined with the data received streams P _R 422 and 421 of the I _R of the phase of detecting and channeling the intensity of the current modulation down. This ensures that the current downstream modulation of the optical seed 453 of the REM 450, which has the content of the P _S and I _{S data} for the phase and intensity modulation, respectively, is counterproductively actuated. Thus, the correct information in the symbol against the data flow stream S _T 410 is printed on the modulated optical seed 454, so that its content S _U information matches the symbol against the data flow stream S _T 410. Considering an SOA and EAM as a phase and intensity modulator, respectively, this cancellation of the information along S _R 420 in the optical seed 453 can be obtained by inverting the information along the optical seeds 453 with a focus adequate feed-forward of the detected signals S _R 420. The unit and polarity of the signals of P _R 422 and I _R 421, as well as the path lengths of the optical seed 453 and the symbols detected SR 420 are thereby select so that the optimal cancellation of the intermediates is obtained with REM 450.

In addition, since the phase modulation with SOA 451 will, in general, be to introduce a small amount of intensity modulation, which carries the information of the signal leading D _SOA 431, a small portion of this signal is introduced which leads to the output of the 405 controller for SOA 451 as signal C 423 to 404 of the driver of the EAM 452. With the delay and the correct unit for this signal C 423, which is set within the 404 controller for the EAM 452, The modulation of the induced intensity of SOA 451 can be compensated.

Referring to Figure 5, it illustrates a ONU 500 for bidirectional transmission of optical networks with a low current intensity and / or phase modulation formats, which includes an integrated transmitter such as upstream REM and a local light source , in accordance with the second preferred implementation of the invention.

The UN 500 differs from the UN 200 in the method of detecting the downlink signal and the optical seed of the REM.

With the inclusion of an optical source 570 that acts as a local oscillator (LO), the detection of the downstream 502 received from the ODN 120 through the optical interface 501 of the UN 500 can be carried out in a consistent manner and it allows the use of more complex formats for QAM the one of descent 502. In this case, the OLT 110 can then also include the polarization control means. In addition, LO 570 is used as a seed source for REM 550 and avoids the need for a CSF. Although the term "remodulator" can be confusing in this scenario with an LO, the terminology maintains the coherence of the drawings.

The wavelength of the light emission 571 and 572 of LO 570 is adjusted to the wavelength of 502 downstream, but is not specified in its spectral deviation, which is fixed, but is generally not zero.

A power splitter 510 passively distributes the 502 downstream to the detection branch where it appears as a 503 signal, and transmits the modulated optical seed 505 of REM 550 to the output of ONU 500, where it appears as above 506 .

Another energy divider 511 is used to mix the downstream transmitted signal 503 with the emitted signal 571 of LO 570, in accordance with the coherent detection principle. The superimposed signal 504 is received by the DEM 520 and, in turn by the set of 530 photo detectors, which are similar to those mentioned for the UN 200. The detected electrical signal 531, which consists of an essential signal, is fed to the RX 540 power network, which is connected through a 541 interface to the network user according to a common telecommunications standard. For the RX 540, the same features that are required for the UN 200, but can also include adaptations and control circuits for the coherent detection system.

REM 550 is essentially composed of an SOA 551 and an EAM 552, which are driven by electrical signals 562 and 563, respectively. The positions of SOA 551 and 552 EAM can be exchanged so that LO 570 offers its 572 seed optical signal to EAM 552 instead of SOA 551. The electric TX 560, which is connected to the network through a 561 interface according to a common telecommunications standard, is responsible for the UN 200 for various electrical functions, but they generally have less requirements than TX 260, due to the simplification of the LCR, which basically contains only one conductor Simple electric and polarization circuits.

Depending on the characteristics of ON 100, an insulator of 580 can be placed at the output of REM 550 to avoid lowering 502, although it is expected to have a weak optical power due to the coherent reception system, to cause interference with the upload channel

LO 570 consists of a suitable light source that can be a laser diode in the simplest case. In the case of the introduction of WDM techniques in EN 100 to increase the density of network customers, LO 570 must have means of adjustability.

Depending on the exact embodiment of the light source of LO 570, it can be a divisor of the additional energy required to divide the light into the two signals of 571 and 572. For the case shown in the figure. 5, this light source is supposed to have two facets, as is usual for laser diodes, so this said energy divider is not necessary.

Referring to Figure 6, which illustrates the possible applications 600 including the integrated, optical transmitter (OTX) 610 for amplitude phase and modulation, in accordance with the present invention.

The OTX 610 is integrated in the transmitter (TX) 601, which transmits the data to the receiver (RX) 602 through the ODN 603. The TX 601 and RX 602 is understood as transmitting and receiving subsystem of a network node in an optical network, or, in the particular case of an optical access network, transmission and reception as in the subsystem and the ONU and OLT, respectively.

In the case of bidirectional data transmission, the reception of an optical input signal within TX 602 is not specified for requests submitted, but can be implemented as in UN 200 or ONU 500. TX 601 can be remotely seedless by visible light or may contain a light source, similar to UN 200 or UN 500, respectively.

The RX 602 may be an optical line termination of a network premises (access) or a network node within a larger (transport) optical network.

Each TX 601 is associated with a set of data transmission sources T1 ... Tn (611a ... n). These electric transmitters can be supplied with data that comes from different operators, various information services or equivalent data generation entities.

Each RX 602 is more associated with an optical receiver (ORX) 613 and a system for receiving data sinks R1 ... Rn (612a ... n). These data sinks are compatible with data sources T1 ... Tn (611a ... n). The optical receiver of the ORX 613 is that there are no more specifications.

Each pair of data sources and data sinks, R1-T1 to Rn-Tn, provides a virtual connection through ODN 603.

The sources T1 ... Tn (611a ... n) has a standardized electric transmitter, which is compatible with the 261 electrical interface. The OTX 610 includes an optical modulator with an SOA architecture and an EAM section, forming a amplitude and phase modulator of 250 or 550. In addition, the OTX 610 includes the features found in TX 401.

The electrical data signals from the sources T1 ... Tn (611a ... n) are combined inside the OTX 610 in a way so that the information received by the sources is included and forwarded to the SOA and EAM sections of the optical modulator.

As an example, in the case of having two sources of T1 and T2, the signal of the electrical data of the T1 is the generation of the signal leading 264 of the SOA 251, while the source T2 is distributed in a manner similar to the signal that conducts 263 for the EAM 252.

To extend the example to the case in four sources T1 ... T4 are present, the first half of the sources, for example, ... T1 T2, is attributed to School 251, while the second half, for example, T3 T4 ... is attributed to EAM 252. The conduction of signals 264 and 263 is then generated as a multi-level signal, which are derived from the data contents supplied by the electrical sources T1 ... T4.

Note that the allocation of resources between SOA 251 and 252 EAM does not necessarily have to be balanced. As an alternative to the given example, a single source, for example, T1, can be attributed to SOA 251, while the other three sources, for example, ... T2 T4, are attributed to EAM 252.

Similarly, the assignment of electrical sources T1 ... Tn (611a ... n) is made for SOA 251 and EAM 252.
Two specific illustrative examples 620 and 630 with respect to the optical application phase and amplitude modulation are shown in Figure 6.

Example 620 shows how to share the infrastructure of ODN 603 among many service operators, while example 630 shows a way to implement within the labeling band in order to switch optical packets.

In example 620 the signals from the electricity sources have been assigned to School 251 and 252 EAM to provide the optical phase (several levels) and the amplitude signals φ1 and Ι2, respectively. These two tributaries φ1 and Ι2 of the optical transmission signal correspond to two different operators, while their different services offered determine the multi-level modulation of each of the tributaries. On the other hand, a single service can be implemented by operators, who use the multi-level modulation of their tributaries associated with the increase in the rate of transmitted data.

In example 630 the two tributaries φ _L and Ι _P of the optical transmission signal are used to make different types of information from TX 601 to the nearest node network 602 of an optical transport network. According to the exchange optical tag, a (possibly) the low data rate tag is added to the payload of the high speed data packet, to allow routing functionality within the optical transport network.

To avoid the use of extra wavelengths or an extension of the packet length, the tag is modulated by the SOA 251 in the phase of the optical signal and therefore of access when reading the information content of the φ _L tributary, while the payload data is modulated by EAM 252 in the amplitude of the optical signal and accessible through the tributary Ι _P.

Claims (13)

Modulation method of a single optical carrier with multiple levels of both amplitude and phase or simultaneously of amplitude and phase by means of an electrical binary data signal (261), using an independent wavelength apparatus, and comprising a method: - Divide the electrical data signal (261) into two binary contributions (263) and (264), - Modulate the optical phase or amplitude of an optical signal with the first contribution (264) of the electrical data signal (261) , by using the element (251), based on a semiconductor optical amplifier (SOA), - Modulate the optical amplitude with the second contribution (263) of the electrical data signal (261), using an element (252) based on an electro-absorption modulator (EAM). The method of claim 1 wherein the electrical data signals with multiple amplitude levels are used for both contributions (263) and (264) to establish a higher order amplitude optical modulation (QAM). The method of claim 1 for which the rate of data symbols electrical contributions (263) for the EAM-based element (252) is a multiple of the rate of data symbols electrical contributions (264) for the element (251) based on SOA. The method of claim 1, wherein two independent electrical data signals (261) with binary amplitude levels (multiple) are used as input data to generate the two contributions (multilevel) (263) and (264). An integrated device (250, 310, 320) for modulating an optical signal with electrical signal data, comprising: - Two electrical inputs (255), (256) to which the two contributions of the electrical data signal are applied, - Two optical ports (254), which may be the same, to which the incident light (204) is inserted and the modulated light (205) is obtained, - An SOA (reflective) architecture (251) to modulate the signal phase optical incident in amplitude with the first contribution of electrical data (264), - An EAM (252) (reflective) for the modulation of the optical signal in amplitude with the second contribution of electrical data (263). The apparatus of claim 5, comprising a single integrated SOA / EAM device. The apparatus of claim 5, comprising only integrated, reflective SOA / EAM device. The apparatus of claim 5, comprising a single integrated SOA / EAM device (320), wherein the second section of the SOA (327) is modulated either with the first contribution of electrical data (325) or by a constant current. The apparatus of claim 5, further comprising - An optical power division system (210) that divides the optical incident signal (202) to the optical transmitter (250) and, - A suitable receiver (230) for the detection of a optical signal modulated with binary data or multiple levels, which is connected to the second output of the optical power division, including optical elements (220) for the detection of the incident signal data. - The electrical interface (240) necessary to acquire the signal detected by the receiver. The apparatus of claim 9, comprising an electronic circuit (262) for light remodulation, which is included after the electrical interface of the optical reception subsystem, to provide information to the optical transmission subsystem and allow correct remodulation of the incident optical signal modulated with the electrical data. The integrated apparatus, the optical transmission of claim 5, further comprising - An optical reception circuit for the detection of data transmitted by an incident optical signal, including the required electrical connections, - A local light source (570) that is connected to the input of the optical transmission apparatus (550), as well as to said optical reception circuit (520, 530), - At least one optical separation device (511) that allows the mentioned optical connections, - At least an optical separation device (510) that connects the input of the optical reception circuits and the optical output of the optical apparatus transmitting through a common, bi-directional optical port (501). A modulation method (620), including the apparatus of claim 5, wherein the data from multiple services, service operators or network users (611a ... n) are combined and transmitted through an optical network, by assigning different data contributions to the modulation of the phase and amplitude of the transmitted optical signal. A modulation method (630), including the apparatus of claim 5, wherein the data corresponding to the phase modulation of the transmitted optical signal is used for simultaneous labeling of the data transmitted in the amplitude modulation of The transmitted optical signal.

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