Optical Coherent Communication: Brings Revolutionary Changes in the Field of Optical Fiber Communications

In modern optical fiber communication, optical coherent communication technology has become a hot topic of research due to its advantages of high sensitivity, high bandwidth and long-distance transmission. This article will introduce in detail the basic principles, key technologies and performance of optical coherent communication in practical applications.

What is optical coherent communication?

Optical coherent communication is a technology that uses the coherence of light to transmit information. Unlike the traditional intensity modulation direct detection (IM/DD) system, optical coherent communication achieves higher signal quality and transmission efficiency by modulating the phase, frequency or amplitude of light and performing coherent detection at the receiving end.

Basic principles of optical coherent communication

Optical modulation

The information signal is loaded onto the optical carrier through a modulator. Common modulation methods include phase modulation (PM), frequency modulation (FM) and amplitude modulation (AM).

Optical transmission

The modulated optical signal is transmitted through optical fiber.

Coherent detection

At the receiving end, the coherent light generated by the local oscillator is mixed with the received signal light, and the original information is obtained by demodulation.

Key technologies of optical coherent communication

Optical modulation technology

Optical modulation technology is the core of optical coherent communication. Taking phase modulation as an example, common modulation formats include QPSK (quadrature phase shift keying) and 16-QAM (hexadecimal quadrature amplitude modulation).

Local oscillator

The local oscillator generates coherent light with a frequency close to that of the signal light, and is a key component for realizing coherent detection.

Mixing and demodulation

The mixer mixes the signal light with the local oscillator light to generate an intermediate frequency signal, and then the original information is restored by the demodulator.

Practical application of optical coherent communication

Long-distance communication

Optical coherent communication performs well in high-capacity, long-distance optical fiber transmission and is widely used in submarine optical cables and terrestrial backbone networks.

Data center interconnection

The demand for high-speed interconnection between data centers has promoted the development of optical coherent communication technology in short-distance applications.

In summary, optical coherent communication technology has brought revolutionary changes to the field of optical fiber communication with its excellent performance. Mastering its principles and applications is of great significance to those engaged in optical fiber communication research and engineering and technical personnel.