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EP-4210242-B1 - SINGLE-FIBER BIDIRECTIONAL OPTICAL TRANSMISSION APPARATUS, WAVELENGTH DIVISION DEVICE AND OPTICAL TRANSMISSION SYSTEM

EP4210242B1EP 4210242 B1EP4210242 B1EP 4210242B1EP-4210242-B1

Inventors

  • LIU, WEI

Dates

Publication Date
20260513
Application Date
20210922

Claims (8)

  1. A single-fiber bidirectional optical transmission apparatus, wherein the single-fiber bidirectional optical transmission apparatus comprises: a first single-light-source coherent optical transceiver, configured to: receive a first optical signal from a first multiplexer/demultiplexer, convert the first optical signal into a first electrical signal, and send the first electrical signal to a first client signal processing apparatus; a second single-light-source coherent optical transceiver, configured to: receive a second electrical signal from the first client signal processing apparatus, convert the second electrical signal into a second optical signal, and send the second optical signal to the first multiplexer/demultiplexer, wherein a wavelength of the second optical signal is different from a wavelength of the first optical signal; and a framing chip, configured to: receive the first electrical signal from the first single-light-source coherent optical transceiver, and send a processed first electrical signal to the first client signal processing apparatus; receive an unprocessed second electrical signal from the first client signal processing apparatus, and send the second electrical signal to the second single-light-source coherent optical transceiver; and provide a second clock signal to the second single-light-source coherent optical transceiver, wherein the second clock signal is extracted by the framing chip from the unprocessed second electrical signal received from the first client signal processing apparatus.
  2. The single-fiber bidirectional optical transmission apparatus according to claim 1, wherein the second single-light-source coherent optical transceiver is further configured to: receive a third optical signal from a second multiplexer/demultiplexer, convert the third optical signal into a third electrical signal, and send the third electrical signal to a second client signal processing apparatus, wherein a wavelength of the third optical signal is the same as the wavelength of the second optical signal, but the optical signals are in opposite directions; and the first single-light-source coherent optical transceiver is further configured to: receive a fourth electrical signal from the second client signal processing apparatus, convert the fourth electrical signal into a fourth optical signal, and send the fourth optical signal to the second multiplexer/demultiplexer, wherein a wavelength of the fourth optical signal is the same as the wavelength of the first optical signal, but the optical signals are in opposite directions.
  3. The single-fiber bidirectional optical transmission apparatus according to claim 2, wherein the single-fiber bidirectional optical transmission apparatus further comprises: a receive-end signal distribution circuit, configured to: receive the first electrical signal from the first single-light-source coherent optical transceiver by using a first electrical input end, and receive the third electrical signal from the second single-light-source coherent optical transceiver by using a second electrical input end; and a control circuit, configured to: control the receive-end signal distribution circuit to output the first electrical signal from a first electrical output end of the receive-end signal distribution circuit, and control the receive-end signal distribution circuit to output the third electrical signal from a second electrical output end of the receive-end signal distribution circuit, wherein the first electrical output end of the receive-end signal distribution circuit is connected to an electrical input end of the first client signal processing apparatus, and the second electrical output end of the receive-end signal distribution circuit is connected to an electrical input end of the second client signal processing apparatus.
  4. The single-fiber bidirectional optical transmission apparatus according to any one of claims 2 to 3, wherein the single-fiber bidirectional optical transmission apparatus further comprises the first multiplexer/demultiplexer and the second multiplexer/demultiplexer; or the single-fiber bidirectional optical transmission apparatus is connectable to the first multiplexer/demultiplexer and the second multiplexer/demultiplexer.
  5. The single-fiber bidirectional optical transmission apparatus according to any one of claims 2 to 4, wherein the single-fiber bidirectional optical transmission apparatus further comprises the second client signal processing apparatus and the first client signal processing apparatus; or the single-fiber bidirectional optical transmission apparatus is connectable to the second client signal processing apparatus and the first client signal processing apparatus.
  6. The single-fiber bidirectional optical transmission apparatus according to any preceding claim, wherein the single-fiber bidirectional optical transmission apparatus further comprises the first multiplexer/demultiplexer; or the single-fiber bidirectional optical transmission apparatus is connectable to the first multiplexer/demultiplexer.
  7. The single-fiber bidirectional optical transmission apparatus according to any preceding claim, wherein the single-fiber bidirectional optical transmission apparatus further comprises the first client signal processing apparatus; or the single-fiber bidirectional optical transmission apparatus is connectable to the first client signal processing apparatus.
  8. The single-fiber bidirectional optical transmission apparatus according to any preceding claim, wherein the single-fiber bidirectional optical transmission apparatus further comprises a clock signal distribution circuit, wherein the framing chip is further configured to provide a first clock signal to the first single-light-source coherent optical transceiver, and wherein the framing chip being configured to provide a first clock signal to the first single-light-source coherent optical transceiver, and provide a second clock signal to the second single-light-source coherent optical transceiver comprises: the framing chip being further configured to: provide the first clock signal to a first clock input end of the clock signal distribution circuit, and provide the second clock signal to a second clock input end of the clock signal distribution circuit; and the control circuit being further configured to: control the clock signal distribution circuit to output the first clock signal from a second clock output end of the clock signal distribution circuit, and control the clock signal distribution circuit to output the second clock signal from a first clock output end of the clock signal distribution circuit, wherein the first clock output end of the clock signal distribution circuit is connected to a clock input end of the first single-light-source coherent optical transceiver, and the second clock output end of the clock signal distribution circuit is connected to a clock input end of the second single-light-source coherent optical transceiver.

Description

TECHNICAL FIELD This application relates to the field of optoelectronic technologies, and in particular, to a single-fiber bidirectional optical transmission apparatus, a wavelength division multiplexing device, and an optical transmission system. BACKGROUND With shortage of optical fiber resources, a single-fiber bidirectional technology is widely used. The "single-fiber bidirectional" means that there is only one optical fiber between two stations, and the optical fiber is configured to transmit optical signals in two directions. For example, FIG. 1 is a schematic diagram of an existing single-fiber bidirectional application scenario. There is only an optical fiber A between a station 1 and a station 2. The optical fiber A is configured to transmit an optical signal from the station 1 to the station 2, and may also be configured to transmit an optical signal from the station 2 to the station 1. Currently, the "single-fiber bidirectional" includes two solutions: a non-coherent optical transceiver and a dual-light-source coherent optical transceiver. The non-coherent optical transceiver currently supports only low-rate optical transmission, and the dual-light-source coherent optical transceiver may support high-rate optical transmission. Therefore, as demands for high-rate optical transmission grow, the dual-light-source coherent optical transceiver solution is increasingly used. FIG. 2 is a schematic diagram of a structure of an existing dual-light-source coherent optical transceiver. The dual-light-source coherent optical transceiver includes a continuous wave (continuous wave, CW) light source at a transmit end and a local oscillator (local oscillator, LO) light source at a receive end. The CW light source is provided for use by a modulator at the transmit end. The LO light source is provided for used by an integrated coherent receiver (integrated coherent receiver, ICR) at the receive end, where the ICR is configured to demodulate an optical signal at the receive end to obtain an intra-frequency signal. In addition, the dual-light-source coherent optical transceiver further includes an optical digital signal processor (optical digital signal processor, oDSP) and an electrical interface. The oDSP is configured to: perform forward error correction (forward error correction, FEC) enhancement on a transmit-end electrical signal and then decompose the electrical signal and send the electrical signal to the modulator at the transmit end, and perform a de-FEC function on a receive-end electrical signal and then send the electrical signal to the electrical interface. The electrical interface is configured to output an electrical signal. With development of technologies, a coherent optical transceiver has a smaller size. A miniaturized coherent optical transceiver has only one laser (which may be considered as a single light source) because a size is too small to place two lasers (that is, dual light sources cannot be provided). For example, FIG. 3 is a schematic diagram of a structure of a miniaturized single-light-source coherent optical transceiver. Compared with a framework diagram of the dual-light-source coherent optical transceiver shown in FIG. 2, a framework diagram of the miniaturized single-light-source coherent optical transceiver includes only one CW light source corresponding to a laser. The CW light source is split into two beams of light sources by using an optical splitter. One beam of light source is provided for use by a modulator at a transmit end, and the other beam of light source is provided for use by an ICR at a receive end, where the ICR is configured to demodulate an optical signal at the receive end to obtain an intra-frequency signal. In this working mode, transmit and receive wavelengths are definitely the same. However, in the single-fiber bidirectional technology, wavelengths of optical signals in two directions are two different wavelengths allowed to be transmitted by a single optical fiber. If wavelengths of optical signals in two directions are the same, optical signals in neither direction can be transmitted. Therefore, the existing single-fiber bidirectional technology cannot use the miniaturized single-light-source coherent optical transceiver. US 2005/025486 A1 discloses a bidirectional wavelength division multiplexing module. US 2017/214463 A1 discloses bidirectional transmission over an elliptical core optical fiber. US 2020/204258 A1 discloses an apparatus and method to improve optical reach in bidirectional optical transmission systems employing single-laser coherent transceivers. SUMMARY Embodiments of this application provide a single-fiber bidirectional optical transmission apparatus, a wavelength division multiplexing device, and an optical transmission system, to implement single-fiber bidirectional optical transmission by using miniaturized single-light-source coherent optical transceivers. The invention is defined by the independent claims hereto appended, with