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WO2008020838A1 - Système et procédé de compensation de dérive thermique pour réseaux optiques - Google Patents

Système et procédé de compensation de dérive thermique pour réseaux optiques Download PDF

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Publication number
WO2008020838A1
WO2008020838A1 PCT/US2006/031810 US2006031810W WO2008020838A1 WO 2008020838 A1 WO2008020838 A1 WO 2008020838A1 US 2006031810 W US2006031810 W US 2006031810W WO 2008020838 A1 WO2008020838 A1 WO 2008020838A1
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WIPO (PCT)
Prior art keywords
optical
pair
optical signals
signals
transceiver
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Ceased
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PCT/US2006/031810
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English (en)
Inventor
Thomas L. Weaver
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Boeing Co
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Boeing Co
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Priority to PCT/US2006/031810 priority Critical patent/WO2008020838A1/fr
Publication of WO2008020838A1 publication Critical patent/WO2008020838A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/60—Receivers
    • H04B10/66—Non-coherent receivers, e.g. using direct detection
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
    • H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
    • H04B10/077—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using a supervisory or additional signal
    • H04B10/0779—Monitoring line transmitter or line receiver equipment
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50—Transmitters
    • H04B10/564—Power control

Definitions

  • the present invention relates to the detection of thermal drift in optical devices used in optical networks, and more particularly to the detection, monitoring and correction for thermal drift in optical devices employing a plurality of independent optical channels.
  • Electromagnetic interference has been a challenge of long standing with mobile platform, and particularly with aircraft electronic systems.
  • the development of fly-by-wire control systems to reduce vehicle weight and volume increases the risk of EMI.
  • fly-by-light systems would eliminate the risk of EMI to various electronic systems used on mobile platforms.
  • fly-by-light systems are difficult to build in a form that is both robust enough to operate in aerospace
  • a principal obstacle in implementing optics based control networks in aerospace applications has been the somewhat limited number of independent optical signals that can be transmitted per optical path (i.e., per optical fiber).
  • a key consideration in making the use of an optical based control network practical in an aerospace application is the ability to increase the number of wavelength channels that can be implemented on each optic path.
  • thermal drift of the wavelength bands associated with the optical channels of a given optical component must be addressed. If thermal drift could be readily compensated for, then the wavelength bands defining the independent optical channels could be placed closer together than what would be possible in a thermally uncompensated for system. This would allow a greater number of wavelength bands to be used in a given optical medium, for example, on a single optical fiber.
  • One approach to controlling thermal drift is employed in the telecommunications industry where presently up to 64 separate wavelength division multiplexing (WDM) channels can be put on a single optical fiber. Implementing this number of separate WDM channels requires very close control of the wavelengths that define each WDM channel.
  • the telecommunication industry's approach to controlling thermal drift is to put all temperature sensitive devices on thermal control units which control the temperature of the devices to within about 0.1 0 C. Those devices are placed inside temperature control enclosures which control the temperature to within about 2.O 0 C. On land, the enclosures are placed in temperature control buildings. At sea, the disclosures are placed at ocean depths of known constant temperature. Obviously, this degree of temperature control is impossible and/or impractical to implement in aerospace applications.
  • Aerospace applications typically involve fewer signals to send, over shorter distances, and inside a vehicle.
  • the cross complexity and mass that would be required to be added into a mobile platform, in the form of complex transmitters and receivers used to put large numbers of signals on single optical fibers does not give aerospace applications the same cost savings that are present for telecommunication applications.
  • an optical based signal in which relatively modest numbers (i.e., typically 20 or less) signals are placed on a single optical fiber. This would allow operating wavelengths to be spaced sufficiently far from each other and the wavelength bands of the various devices made sufficiently wide, such that the use of optical fibers becomes more practical in an aerospace application. Then, the temperatures of the optical devices being controlled on the mobile platform can be allowed to drift, since because of the larger spacing between bands, the signals cannot cross into each others' bands. Furthermore, if sufficiently large bandwidth channels are employed, then some signals will always pass through their designated channels, even when the bands (i.e., channels) on a transmitter and those of the other optical component receiving the optical signals, such as a router, do not accurately align.
  • bands i.e., channels
  • the present invention is directed to a system and method for determining thermal drift in an optical device located remotely from an optical transceiver and experiencing different thermal conditions than the optical transceiver.
  • the system involves using the optical transceiver to transmit a first pair of narrow band optical signals within a single, predetermined wavelength band to the optical device.
  • the optical device receives a first pair of optical signals and generates a second pair of narrow band optical signals back to the transceiver over a suitable optical medium. If the wavelength bands of the input of the optical device have shifted due to thermal drift, at least one of the first pair of optical signals will be attenuated when it is received back at the transceiver.
  • the degree of attenuation, as well as which one of the pair of optical signals is attenuated more than the other, can be used to determine the direction and magnitude of thermal drift of all of the wavelength bands at the remotely located optical device.
  • the above- described detection of thermal drift of the wavelength bands at the optical device is corrected by the use of a thermal subsystem.
  • the thermal subsystem controllably cools or heats the optical transceiver as needed to induce a controlled shift of the wavelength bands of the transmitter, representing the independent channels over which optical signals are transmitted from the transmitter of the optical transceiver.
  • RF signals are impressed onto the optical signals transmitted from the transmitter to the optical device.
  • the optical device then transmits the optical signals with the RF signals impressed thereon to an optical receiver.
  • the use of RF signals impressed on the optical signals enables optical signals that have shifted into adjacent passbands, as a result of temperature differences between the optical device and the optical receiver, to be readily detected and cancelled at the receiver.
  • a filter media is used at an input of the receiver to shift the wavelength bands to which the receiver is sensitive to match the wavelengths of the optical signals being transmitted from the optical device to an optical receiver.
  • the optical media in one preferred form, may comprise a filter.
  • the optical media may be physically moved so that its orientation relative to the input of the receiver, is altered to cause the needed degree of wavelength shifting.
  • the filter media may be deformed, such as by stretching or compression, to achieve the needed degree of shifting of the optical signals being received at the input of the receiver.
  • a greater plurality of receive channels for the optical receiver are implemented than the number of optical channels used for optical signals transmitted by the optical transmitter.
  • the number of receive channels may comprise any multiple of transmitter channels.
  • the receive channels are further arranged such that no bandwidth gaps (i.e., no "dead bands") are present between adjacent receive channels.
  • no bandwidth gaps i.e., no "dead bands”
  • optical device by introducing a controlled degree of wavelength band shifting at the optical transceiver allows the wavelength bands to be narrower and spaced more closely together. This allows a greater number of independent optical channels to be implemented on a given optical medium, such as on a given optical fiber, without the
  • the system and method of the present invention also allows an optical based control network to be implemented on a mobile platform which allows a reduction in cost, weight and volume of the components used to implement a control network on a mobile platform.
  • an optical based system eliminates the EMI issues that would otherwise need to be addressed and compensated for in various mobile platform
  • Figure 1 is a simplified block diagram of a preferred embodiment of the
  • Figure 2 is a diagram of signals being transmitted between an optical transmitter and an optical receiver via a remotely located optical router, illustrating alignment of the passbands of the router when the router is at the same temperature as the receiver and transmitter;
  • Figure 3 is a diagram illustrating misalignment of the passbands of the optical router and the result of this misalignment on the optical signals being received at the receiver;
  • Figure 4 is a simplified block diagram of an alternative preferred embodiment of the present invention incorporating a subsystem for modulating RF signals onto the optical signals transmitted from the transmitter to the optical router and a subsystem for detecting the RF modulated optical signals at the receiver;
  • Figure 5 is a waveform diagram of the optical signals having RF signals impressed thereon, and further illustrating when the passbands of the optical router are aligned with the passbands of the optical receiver;
  • Figure 6 is a graph illustrating the effect on the optical signals when the optical receiver passbands are misaligned with the optical router passbands;
  • Figure 7 is yet another alternative preferred embodiment of the present invention incorporating a filter positioned at an input of the optical receiver for controllably shifting the wavelength bands of the optical signals being received by the receiver to compensate for thermal drifting of the passbands of the optical router; and
  • Figure 8 is a graph illustrating yet another alternative preferred implementation of the present invention in which a greater number of receive channels than transmit channels are used for receiving the optical signals at the optical receiver.
  • DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0027] The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
  • FIG 1 there is shown a system 10 in accordance with a preferred embodiment of the present invention. While the system 10 is shown as being implemented on aircraft 12, it will be appreciated that the system 10 could be implemented on any mobile platform where an optical control network is desired. The system 10 could also be employed in a fixed structure where an optical system is desired, and where an optical control device of the network is to be located in an ambient environment that causes the optical device to experience significant temperature changes that differ from those experienced by an optical transmitter.
  • the system 10 in this example, includes an optical device 14 in the form of an optical router coupled via a pair of optical fibers 16 and 18 with an optical transceiver 20.
  • the optical transceiver 20 includes an optical transmitter 22 and an optical receiver 24 located within a common housing or enclosure 26.
  • the optical transceiver 20 is in bi-directional communication with a control subsystem 28.
  • the optical transceiver 20 is also in communication with a heating/cooling subsystem 30.
  • the control subsystem 28 is further in bi-directional communication with the heating/cooling subsystem 30.
  • the control subsystem 28 can be an independent subsystem as shown in Figure 1 or it can be integrated into the transmitter 22.
  • optical fibers 16 and 18 While only two optical fibers 16 and 18 have been illustrated in Figure 1 , it will be appreciated that typically a larger number, for example, 4-8 optical fibers will be coupled between the optical transceiver 20 and the optical router 14. Also, while optical fibers 16 and 18 have been used for explanation purposes, other optical media such as free space, photonic bandgap fibers, or photonic crystals could be employed in lieu of optical fibers. Also, while an optical router will be used for purposes of explanation, it will be appreciated that the teachings of the present application could be used with any form of optical multiplexer, de-multiplexer, "add-drop", or other component where changing operating temperature of the device will cause thermal drifting of it optical channels.
  • wavelength division multiplexing is used to transmit a plurality of narrow band optical signals 32 over optical fibers 16 from the optical transmitter 22 to the optical router 14.
  • the optical router 14 routes the signals as needed to various aircraft subsystems which are typically clustered together in groups, for example, groups of 12 to 16 components. This will be further explained in the following paragraphs.
  • the optical router 14 typically includes a filter having a plurality of wavelength bands which may also be termed "passbands".
  • the optical device 14 receives each one of the optical signals 32 within a specific passband and returns an optical signal 34 over a corresponding passband to the optical receiver 24.
  • each passband forms a separate optical channel. Due to the fact that the optical transceiver 20 is located in a different location in the mobile platform 12 than the optical router 14, the router 14 will often be experiencing a different ambient temperature than the optical transceiver 20.
  • the control system 28 is used to monitor the received signals 34 and to shift the transmitted signals 32 so that the wavelength centers of each of the signals 32 match the centers of the passbands of the optical router 14.
  • the control system 28 does this by controlling the heating/cooling subsystem 30 to either heat or cool the transmitter portion 22 of the optical transceiver 20 as needed to cause shifting of the optical signals 32 such that their wavelength centers remain centered within the passbands of the optical router 14.
  • the system 10 essentially forms a "closed loop" end system in which the received optical signals 34 are monitored and the temperature of the optical transceiver 20 is continuously controlled, in real time, via the heating/cooling subsystem 30. This enables the optical signals 32 to "track" the shifting passbands of the optical router 14.
  • FIG 2 the operation of the system 10 will be further described in connection with a simplified diagram of the passbands 36 used by the optical router 14.
  • the optical transmitter 22 and the optical receiver 24 are illustrated on opposite sides of the optical router 14 merely to aid in explaining the alignment of the optical signals 32 and 34 with the passbands 36.
  • the transmitter 22 and receiver 24 are actually located together in housing 26, as shown in Figure 1.
  • a typical optical filter shifts its passband by about 0.026nm per degree C. Over a 18O 0 C range from -55°C to +125 0 C range, the passbands of the router shift by about 4.7nm. Without the thermal drift compensation of the present invention this large of a passband shift would require passbands that are about 8nm wide and on 10.0nm centers. However, 10nm spacing of 8nm bands means that 48 nm of wavelength are required to carry just four optical signals. But four signals (i.e., channels) per optical fiber is insufficient to be beneficial from a cost/benefit standpoint in aerospace applications.
  • detecting the thermal drift of the passbands of the router 14 is accomplished by generating two narrow band optical signals as a "first" or “temperature probe” optical signal 32bi, 32b 2 .
  • the first optical signal pair 32bi, 32b 2 is centered within a passband 36b of the optical router 14, which can be viewed as "channel B".
  • Optical signals 32a and 32c are transmitted in passbands 36a and 36c respectively (channels A and C).
  • the passbands 36a-36c in this example, are illustrated as having 4nm wavelength bands positioned on 5nm spacing.
  • the passbands 36a-36c of the router 14 have their centers aligned with the optical signals 32a-32c, then the magnitude of the signals 34a-34c transmitted back by the router 14, and received by the optical receiver 24, will each be approximately the same magnitude as their corresponding signals 32a-32c.
  • the passbands 36a-36c do not have perfectly flat tops, but rather rounded tops.
  • the pair of optical signals 32bi and 32b 2 and spacing these narrow band optical signals both within a 4nm wavelength band the attenuation of one or other can be detected.
  • signals 32a and 34c are also slightly reduced in intensity as a result of no longer being centered at the wavelength centers of the passbands 36a and 36c, respectively.
  • the control subsystem 28 monitors the second pair of signals 34bi and 34b 2 sent by the optical router 14 and from the degree of attenuation of one or the other of this pair of signals, as well as which one of the pair is attenuated, determines the degree of thermal shift of the passbands 36a-36c of the optical router 14.
  • the control subsystem 28 causes the heating/cooling subsystem 30 to heat or cool the transmitter 22 as needed to apply a real time correction to the narrow band lasers used in the optical transmitter 22.
  • the correction shifts the signals 32a-32c either higher or lower along the wavelength spectrum so that the centers of the optical signals 32a-32c are centered with the passbands 36a-36c of the optical router 14.
  • the system 10 does not attempt to control the temperature of the optical router 14, but instead focuses on controlling the temperature of the optical transmitter 22 in a manner that induces a controlled amount of thermal shifting of the signals 32a-32c from the transmitter as needed to match the thermal shifting of the passbands 36a-36c. This enables the received signals 34a-34c received by the optical receiver 24 to be maintained as strong in magnitude as possible.
  • the passbands 36a-36c can each be made much narrower.
  • WDM wavelength division multiplexing
  • groups typically of 12 to 16.
  • one motor in an aerospace electrical actuator may send 12 separate optical sensor signals to a flight control computer.
  • wavelength division multiplexing channels of an optical router would need to be spaced 10nm apart and only 4 signals could be put into a single optical fiber.
  • the system and method 10 of the present invention thus allows the use of an optical network to be implemented on a mobile platform with significantly fewer optical fibers being required for a given implementation.
  • the system and method 10 further eliminates concerns with EMI that would otherwise be present with fly-by-wire control systems.
  • the system and method 10 further reduces the mass, complexity and cost of an optical control network by its ability to "squeeze" more optical channels onto a given optical fiber without the risk of performance degradation that would be otherwise incurred from the thermal drift experienced by the optical router 14.
  • FIG. 1 an alternative preferred implementation of the present invention is illustrated and designated by reference numeral 100.
  • Components in common with system 10 have been labeled with corresponding reference numerals having a prime (') symbol.
  • the optical transmitter 22' and the optical receiver 24' are no longer located within a common housing or enclosure, but are instead located remote from each other.
  • the optical device 14' is located remotely from the optical transmitter 22' and the optical receiver 24'. Since the optical transmitter 22' and optical receiver 24' are not located in a common enclosure, they will not necessarily experience the same ambient temperature, and thus may not be at the same operating temperature.
  • the passbands at the output of the optical device 14' may not be aligned with the passbands at the input of the optical receiver 24', and the passbands at the input of the optical receiver 24' will not necessarily track the wavelength centers of the transmitted signals from the optical transmitter 22'.
  • the thermal drift of the optical receiver 24' cannot simply be controlled by heating/cooling it via the heating/cooling subsystem 30' because the optical transmitter 22' and the optical receiver 24' are located remotely from each other.
  • the optical receiver 24' may be located in an avionics bay or at some other area where it would be undesirable to attempt to heat the optical receiver 24'.
  • an alternative system for detecting when the optical device 14' is operating at a different temperature from the optical receiver 24', and thus introducing misalignment of the passbands at the output of the optical device 14' with the passbands of an input filter of the optical receiver 24'.
  • This embodiment accomplishes detection of this router 14'/receiver 24' passband misalignment by impressing a unique (i.e., different) radio frequency (RF) modulation signal from an RF modulation subsystem 40 onto each of the optical signals 32a, 32b and 32c.
  • RF radio frequency
  • a processor 42 is used in connection with the optical receiver 24' to detect when an RF modulated optical signal is being received in a passband that it should not be received in, thus indicating misalignment of the two passbands.
  • a variety of different types of signals can be readily impressed on the continuous wave outputs of the narrowband lasers used to form the optical signals 32.
  • sinusoidal excitation signals such as AM, FM and Phase Modulation (PM) could be employed.
  • Digital signals could also be modulated onto the optical signals 32a-32c, and separated from each other by alternating them with analog signals. In either event, the RF modulations allow positive identification of each of the optical signals 32a-32c, even in the event that temperature-induced wavelength drift of the receiver 24' causes a signal from one channel of the router 14' to cross into an adjacent channel at the receiver 14' input
  • FIG. 5 an example of the above-described modulation scheme is illustrated.
  • An 810 KHz signal is impressed on optical signal 32ai.
  • a 600 KHz signal is impressed on optical signal 32a 2 .
  • a 1.0 MHz signal is impressed on optical signal 32b, and a 2.1 MHz excitation signal is impressed on signal 32c.
  • optical signals 32ai and 32a 2 can be viewed as being placed on channel "A”.
  • Optical signal 32b can be viewed as being placed on an optical channel "B”, and optical signal 32c on channel "C”.
  • the passbands of the router 14' are designated by waveform 44.
  • the passbands of the receiver 24' are designated by waveform 46.
  • the specific frequencies above are merely exemplary and may be varied.
  • the modulated signals appear as indicated by reference numeral 48 in Figure 5.
  • the optical signals 32a-32c are centered within their respective passbands 44. Since the receiver 24 passbands 46 are aligned with the router passbands 44, the signals received by the optical receiver appear as indicated by reference numeral 50.
  • the RF modulated optical signals 32a-32c remain centered within the receiver passbands 46 and are substantially of the same magnitudes as indicated by reference numeral 48. It will be noted, however, that the RF modulated optical signals 32a-32c, as indicated by reference numeral 48, are reduced slightly in magnitude, as compared to the signals 32a-32c output by the transmitter 22'.
  • the effect on the RF modulated optical signals 32a-32c can be seen when the router passbands 44 do not align with the passbands 46 of the optical receiver 24'.
  • the RF modulated output signals 32a-32c as indicated by reference numeral 48, are still aligned with the router passbands 44.
  • the RF modulated optical signals 32a-32c now have drifted or "bled" into adjacent channels. Specifically, a portion of signal 32a 2 has now drifted into channel B, and a portion of signal 32b has drifted into channel C.
  • the optical receiver 24' may be located in an avionics bay, near the transmitter 22', and will therefore not be as hot as the filters in the optical router 14', which are located in a considerably warmer, remote location of the mobile platform 12.
  • Modulating RF signals of different frequencies onto the optical signals 32a-32c allows the processor 42 ( Figure 4) to detect when an unwanted signal is present within a given optical channel and to cancel (i.e., reject) that portion of the signal within a given channel.
  • processor 42 rejects that portion of optical signal 32a 2 that is present within channel B in Figure 6.
  • the processor 42 rejects that portion of optical signal 32b that is present within channel C.
  • the receiver 24' Since the signals received by the optical receiver 24' in Figure 6 have also been attenuated significantly, the receiver 24' also makes a magnitude compensation to the received signals designated by reference numeral 50 in Figure 6.
  • One way of achieving this compensation is by directly measuring a temperature of the optical receiver 14' using a suitable temperature sensor 42a in communication with the processor 42. If the characteristics of the filter of the optical receiver 24' are known, then the difference in temperature between the optical router 14' and the optical receiver 24' can be determined.
  • a suitable look-up table can be used which includes magnitude correction values dependent upon the temperature to correct for the signal attenuation caused by the mismatch of the receiver passbands
  • FIG 7 another alternative preferred embodiment of the present invention is illustrated and represented by reference numeral 200.
  • This approach does not make use of impressing RF modulation signals onto the optical signals 32a-32c as described in connection with Figures 4-6, but instead uses a mechanically adjustable input filter 202 to shift the passbands 46 at an input side of the optical receiver 24'.
  • the mechanically adjustable input filter 202 is controlled by a controller 204 that monitors operation of the optical receiver 24', and more particularly its temperature, and uses the temperature information to apply suitable control signals to alter the mechanically adjustable input filter 202 as needed to achieve the needed degree of passband 46 shifting.
  • the mechanically adjustable input filter 202 may comprise devices as diverse as Bragg gratings, Fabry-Perot etalons, Surface Acoustic Wave devices, and Micro-Electro-Mechanical Machine gratings.
  • the mechanically adjustable input filter 202 may be physically altered in position relative to the optical receiver 24' to achieve the needed degree of shifting of the passbands 46. Alternatively, it may be physically deformed such as by mechanical stretching or compression, which also will cause the needed shifting of the passbands 46.
  • the controller 204 also makes use of a look-up table which includes information correlating the temperatures of the optical transmitter and receiver 24', and the transmission characteristics of the filters in the optical device 14' and the receiver. With that information, it is possible for the controller to determine the wavelength shift of the device 14' and alter the emission wavelengths of the transmitter and the passbands of the receiver 24' to center each signal in each passband of the optical device 14'.
  • the optical receiver 24' still needs to make sense of the signals present within each of the passbands 46.
  • the use of multiple receive channels for each passband of the router 14' allows the signals 32 present within each passband of the optical router 14' to be strongly detected by the optical receiver 24'.
  • This approach also avoids the need to change the gain of the receive amplifiers used within the optical receiver 24', which would otherwise be needed to compensate for the weak optical signals 32a-32c received by the optical receiver 24', but at the cost of increased noise in the receiver 24'.
  • the signals 32a-32c can be detected more readily. While two receive channels are shown for each router passband, it will be appreciated that any multiple of receive channels could be employed. Thus, three, four or more receive passbands per router passband could be employed. From a practical standpoint, however, the maximum number of receive passbands that may be employed per router passband will depend largely on the bandwidth of each router passband.
  • the temperature of the transmitter 22' is still controlled as described in connection with the system of Figure 4, however, no shifting of the passbands 46 of the receiver 24' is employed.
  • the temperature of the optical router 14' will be sensed in two ways. The first is to compare the ratio of the two signals that appears in only the first passband (channel A). This is the method identified previously. In practice, it is only reliable if the drift of the passband with respect to the two signals is so small that though one signal is in the roll-off region of the passband, and so is smaller than the signal near the center of the passband, the smaller signal is still fairly strong, such as greater than 50% of the strength of the strong signal.
  • the drift of the passbands is such that one signal is near the extreme edge of the passband, its strength at the detector in the receiver may be close to the noise level of the detection system. That means that the strength of the weak signal is more uncertain than the strength of the strong signal. Dividing the uncertain, weak signal by the certain, strong signal to obtain the ratio, and hence, the temperature, gives a value with the uncertainty of the weak signal.
  • the second approach makes use of the large number of passbands of the present receiver 24'. It is useful for the case when drift of the passbands is large. In that case, rather than use the very weak signal that is passed by the filter in the first passband, it is better to use the stronger version of the same signal that is passed by the filter in the adjacent passband.
  • the ratio of the two optical signals 32ai and 32bi appearing in the first passband (channel A) is used, but for large drifts, the strength of the signal 32ai in the first passband (channel A) is compared with the strength of the signal 32a 2 in the second (adjacent) passband (channel B).

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  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
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Abstract

L'invention concerne un système et un procédé permettant de détecter et de compenser la dérive thermique dans un réseau optique de manière à pouvoir utiliser un nombre accru de canaux optiques sur un support optique donné, comme par exemple sur une fibre optique simple. Une paire de signaux optiques de bande étroite, étroitement espacés et provenant d'un émetteur optique, font office de signal de 'sonde de température'. Les deux signaux à bande étroite sont centrés dans une bande passante d'un filtre de dispositif optique, comme un routeur optique. Lorsque les deux signaux à bande étroite sont retransmis vers un récepteur optique par le biais du routeur, les magnitudes des deux signaux sont comparées et une détermination peut être réalisée quant à la magnitude et la direction de la dérive thermique des bandes passantes du filtre du routeur optique. On utilise ensuite un sous-système de commande pour commander un sous-système de chauffage/refroidissement pour réchauffer ou refroidir l'émetteur et induire un décalage dans les signaux optiques alors générés par l'émetteur pour conduire les signaux optiques émis à suivre de manière effective le centre des bandes passantes du routeur optique.
PCT/US2006/031810 2006-08-16 2006-08-16 Système et procédé de compensation de dérive thermique pour réseaux optiques Ceased WO2008020838A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5838470A (en) * 1995-07-27 1998-11-17 University Technology Corporation Optical wavelength tracking receiver
WO2000038283A1 (fr) * 1998-12-23 2000-06-29 Brown University Research Foundation Dependance thermique d'une emission laser provenant d'un milieu diffuseur contenant un colorant a laser
US20030063636A1 (en) * 2001-10-01 2003-04-03 Goro Sasaki Multimode semiconductor laser module, wavelength detector, wavelength stabilizer, and Raman amplifier
EP1324516A2 (fr) * 2001-12-21 2003-07-02 Agilent Technologies, Inc. (a Delaware corporation) Procédé et dispositif de détection de diaphonie

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5838470A (en) * 1995-07-27 1998-11-17 University Technology Corporation Optical wavelength tracking receiver
WO2000038283A1 (fr) * 1998-12-23 2000-06-29 Brown University Research Foundation Dependance thermique d'une emission laser provenant d'un milieu diffuseur contenant un colorant a laser
US20030063636A1 (en) * 2001-10-01 2003-04-03 Goro Sasaki Multimode semiconductor laser module, wavelength detector, wavelength stabilizer, and Raman amplifier
EP1324516A2 (fr) * 2001-12-21 2003-07-02 Agilent Technologies, Inc. (a Delaware corporation) Procédé et dispositif de détection de diaphonie

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