JP2015032937A - Optical transceiver and control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a possibility of giving damage to a reception side light-receiving element due to a reason that a light transmitting level at a distance measuring signal transmission side is not made appropriate for reception at a reception side, in measurement of the transmission distance between optical communication devices whose optical transmission levels are adjustable according to the transmission distance.SOLUTION: An optical transceiver comprises light-emitting means whose output signal optical power is at or below the maximum optical reception level of an opposite light-receiving element connected via a prescribed transmission path, and is set to a prescribed level which is larger than the minimum light-receiving level of the opposite light-receiving element by a prescribed amount corresponding to loss on the transmission path.

Description

  The present invention relates to an optical transceiver and a control method.

  An optical transceiver is mounted in an optical communication device used in an optical communication network, a backbone of a mobile phone line, or the like. A device equipped with an optical transceiver is required to be used for various communication systems, and has been adapted to a wide communication distance from a short distance to a long distance. However, optical transceivers have different optical transmission levels depending on communication distances, and products are also different. Therefore, devices equipped with optical transceivers have different optical transceiver products according to communication distances. For this reason, a device equipped with an optical transceiver is expensive to develop and manufacture in order to support various transceivers. As a method that can reduce such cost, it is possible to adjust the optical transmission level in accordance with the communication distance in an apparatus equipped with the optical transceiver, and to reduce the number of products corresponding to the communication distance of the optical transceiver. A technique for adjusting the optical transmission level according to the communication distance is disclosed in Patent Document 1.

  The technique disclosed in Patent Document 1 is as follows.

  First, a light reception level monitor unit of an ONU (Optical Network Unit) detects a light amount level received by a PD (Photo Diode), and based on the detected light amount level, the light output level control unit detects the light output level. Make adjustments.

  Next, the distance from the OLT to the ONU is measured under the control of a distance measurement control unit of an OLT (Optical Line Terminal).

  As this distance measurement method, for example, first, a distance measurement start signal is transmitted from the OLT, a response signal from the ONU for the distance measurement signal is received, and a delay from the distance measurement start signal transmission to the reception of the response signal is received. There is a method of measuring distance according to time.

  Based on the distance information thus measured, the ONU control information generation unit calculates the transmission loss at that distance, and determines the optical output level for each signal of 1 Gbps and 10 Gbps according to the transmission loss.

JP 2008-054444 A

  In the technique disclosed in Patent Document 1, it is not guaranteed that the level of the optical signal transmitted by the OLT is an appropriate level for receiving the optical signal by the light receiving element of the ONU before the distance measurement. For this reason, when an APD (Avalanche Photo Diode) is used as a light receiving element, there is a concern that a highly sensitive APD may be destroyed if an optical signal transmitted by the OLT is received at a high level by the ONU. .

  In other words, in the measurement of the transmission distance between optical communication devices that can adjust the optical transmission level according to the transmission distance, the optical transmission level on the transmission side of the distance measurement signal is an appropriate level for reception on the reception side. However, there is a problem that the light receiving element on the receiving side may be damaged.

  An object of the present invention is to provide an optical transceiver and a control method for solving this problem.

  In the optical transceiver of the present invention, the output signal light power is equal to or lower than the maximum light receiving level of the counter light receiving element connected via the predetermined transmission path and is lower than the minimum light receiving level of the counter light receiving element in the transmission path. The light-emitting means is set to a predetermined level that is larger by a predetermined amount corresponding to the loss.

  In the optical transceiver control method of the present invention, the output signal light power of the light emitting means is less than or equal to the maximum light reception level of the counter light receiving element connected via a predetermined transmission path and is less than the minimum light receiving level of the counter light receiving element. And a light emitting step of setting a predetermined level larger by a predetermined amount corresponding to the loss in the transmission path.

  According to the present invention, in the measurement of the transmission distance between optical communication devices capable of adjusting the optical transmission level according to the transmission distance, the optical transmission level on the transmission side of the distance measurement signal is a level suitable for reception on the reception side. Therefore, it is possible to prevent damage to the light receiving element on the receiving side.

It is a figure which shows the structural example of the optical transceiver in the 1st Embodiment of this invention. It is a figure which shows the structural example of the optical transceiver in the 2nd Embodiment of this invention.

  A first embodiment of the present invention will be described with reference to the drawings.

  In this embodiment, it is mounted on an optical communication device capable of adjusting the optical transmission level according to the transmission distance, measures the transmission distance between the own device and the opposite device, and determines its own light based on the measurement result. An optical transceiver for setting a transmission level will be described. In the measurement of the transmission distance, setting the optical transmission level on the transmission side of the distance measurement signal will be described.

  First, the configuration of the optical transceiver in this embodiment will be described with reference to FIG.

  FIG. 1 shows a configuration example of an optical transceiver in the present embodiment. The optical transceiver 100 includes an optical module 110 and a control unit 120.

  The optical module 110 includes a light emitting element 111 and a light receiving element 112. The light emitting element 111 and the light receiving element 112 are, for example, optical components including a laser diode and an avalanche photodiode, respectively.

  The control unit 120 includes a driver 121, a controller 122, and a memory 123.

  Each part of the optical transceiver will be described.

  The light emitting element 111 transmits an optical signal.

  The light receiving element 112 receives an optical signal.

  The driver 121 drives the light emitting element 111.

  The controller 122 performs control of the driver 121, calculation of a transmission distance, and the like.

  The memory 123 stores a drive current value of the driver 121 and the like.

  Next, the operation of the optical transceiver 100 in the present embodiment will be described with reference to FIG.

  It is assumed that an optical communication device similar to the optical communication device on which the optical transceiver 100 is mounted is opposed to the same device and the opposite device performs the same operation simultaneously. However, the operation will be described only for the own device.

  First, a signal indicating the start of distance measurement is input to the optical transceiver 100 from the outside. As a result, the bias current and the modulation current are set in the driver 121 so that the light output of the light emitting element 111 is performed at the same level as the maximum light reception level of the light receiving element of the opposing device. Note that the values of the bias current and the modulation current are calculated in advance based on the value of the maximum light reception level of the light receiving element of the opposing device and stored in the memory 123. The light output of the light emitting element 111 may be equal to or lower than the maximum light reception level of the light receiving element of the opposing device. The driver 121 drives the light emitting element 111 with the set bias current and modulation current, and the light emitting element 111 transmits an optical signal. On the other hand, the light receiving element 112 receives the optical signal transmitted from the opposite device, and measures the optical reception level. At this time, it is not necessary to identify the signal itself. For example, the controller 122 calculates the transmission distance between the own device and the opposite device by the following equation.

Transmission distance [km] = ((opposite device) optical transmission level [dBm]-optical reception level [dBm]) / transmission loss [dB / km]
Note that the transmission loss value is stored in the memory 123 in advance, and may be a minimum value in an assumed range, for example. Further, the transmission distance may be, for example, a design maximum value as an upper limit.
The values of the bias current and the modulation current that lead the light output of the light emitting element 111 at a level suitable for the transmission distance and the characteristics of the light emitting element 111 and the light receiving element of the counter device are stored in the memory 123 in advance. The driver 121 drives the light emitting element 111 with a bias current and a modulation current having values corresponding to the calculated transmission distance, and the light emitting element 111 transmits an optical signal.

  As described above, if the light output level of the distance measurement signal is set to be equal to or lower than the maximum light reception level of the light receiving element of the opposing device, even if an avalanche photodiode is used as the light receiving element, it is destroyed by the input light of the distance measuring signal. There is no. In this way, in the measurement of the transmission distance between optical communication devices that can adjust the optical transmission level according to the transmission distance, the optical transmission level on the transmission side of the distance measurement signal is set to a level appropriate for reception on the reception side. Thus, it is possible to prevent damage to the light receiving element on the receiving side.

  Next, a second embodiment of the present invention will be described with reference to the drawings.

  First, the configuration of the present embodiment will be described with reference to FIG.

  FIG. 2 shows a configuration example of the optical transceiver in this embodiment. The optical transceiver 200 includes a light emitting element 210.

  The light emitting element 210 transmits an optical signal.

  Next, the operation of the optical transceiver 200 in the present embodiment will be described with reference to FIG.

  The light emitting element 210 outputs signal light having a power set to a level equal to or lower than the maximum light receiving level of the counter light receiving element connected via the transmission path. It is assumed that the output signal light has a power higher than the minimum light receiving level of the counter light receiving element when it reaches the counter light receiving element.

  According to the above, in the measurement of the transmission distance between the optical communication devices that can adjust the optical transmission level according to the transmission distance, the optical transmission level on the transmission side of the distance measurement signal becomes a level suitable for reception on the reception side. It is possible to prevent the receiving side light receiving element from being damaged.

  The present invention is applicable to an optical transceiver and a control method.

DESCRIPTION OF SYMBOLS 100 Optical transceiver 110 Optical module 111 Light emitting element 112 Light receiving element 120 Control part 121 Driver 122 Controller 123 Memory 200 Optical transceiver 210 Light emitting element

Claims (6)

  The output signal light power is equal to or less than the maximum light reception level of the counter light receiving element connected through the predetermined transmission path and larger than the minimum light reception level of the counter light receiving element by a predetermined amount corresponding to the loss in the transmission path. An optical transceiver comprising light emitting means set at a predetermined level. A light receiving means connected to the opposing light emitting element via the predetermined transmission path;
2. The controller according to claim 1, further comprising a controller that determines a power level of the signal light output from the light emitting means based on a power level of the signal light received from the counter light emitting element by the light receiving means. Optical transceiver.   The determination of the signal light power level is performed by using the transmission distance of the predetermined transmission path or at least one output or input characteristic of the light emitting means, the counter light receiving element, the counter light emitting element, or the light receiving means as a parameter. The optical transceiver according to claim 2.   The output signal light power of the light emitting means is equal to or less than the maximum light reception level of the counter light receiving element connected via the predetermined transmission path and corresponds to the loss in the transmission path than the minimum light receiving level of the counter light receiving element. An optical transceiver control method comprising a light emitting step of setting a predetermined level larger by a predetermined amount.   A control step of determining a power level of the signal light output in the light emission step based on a power level of the signal light received from the counter light emitting device by a light receiving means connected to the counter light emitting device via the predetermined transmission path; The method of controlling an optical transceiver according to claim 4.   The determination of the signal light power level is performed by using the transmission distance of the predetermined transmission path or at least one output or input characteristic of the light emitting means, the counter light receiving element, the counter light emitting element, or the light receiving means as a parameter. The method of controlling an optical transceiver according to claim 5.

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