Optical duplication technology

Multiplexing technology is a technology that transmits multiple different signals simultaneously on the same transmission line without interfering each other in order to improve the utilization rate of communication lines. In this article, we will introduce several optical duplication technologies.

1, optical time division multiplexing technology

Optical time division multiplexing (OTDM) is a kind of multi-channel optical signal multiplexing in time domain using high-speed switch. The basic principle of OTDM is to divide the same carrier wavelength into periodic frames at the transmitter, and each frame is further divided into a number of time slots. According to the time slot allocation principle, each source can only send signals to the channel according to the specified time slot within each frame. Under the condition of synchronization, the receiver retrieves the respective signal in each time slot without mixing.

The advantages of OTDM are that it can obtain higher rate-bandwidth ratio, overcome the limitations of many factors, such as the gain unflattening of erbium-doped fiber amplifier (EDFA) and the nonlinear effect of four-wave mixing (FWM), and solve the competition of multiplexed ports to increase the flexibility of all-optical networks.

2. Optical wave multiplexing technology

Light waves reuse is more than a simultaneous transmission in a single fiber wavelength light signal of a technology, English abbreviation for WDM, the basic principle of it is in different wavelength optical signal combination, the sender will coupled to fiber optical fiber transmission of the same root, separated the combination wavelengths of light signal at the receiving end, and further processing, after recovering the original signal into different terminals. The technology is the most studied, the fastest growing, and the most widely used.

3. Optical subcarrier multiplexing technology

Optical subcarrier multiplexing (OSCM), the baseband signal is first modulated to the GHz subcarrier (electrical domain), and its subcarrier is modulated to the THz optical carrier (optical domain). Subcarrier channel multiplexing and demultiplexing are carried out in electrical domain. Several channels of subcarrier multiplexing can share one expensive optical device and reduce equipment cost. Subcarrier multiplexing is limited by the available bandwidth of electrical and optical devices, which limits the maximum subcarrier frequency and data rate. Subcarrier multiplexing can be combined with WDM if the bandwidth of optical fiber is more utilized.

4. Optical code division multiplexing

Optical code division multiplexing (OCDM), its working principle is to fill different channel signals with different code sequences orthogonal to each other, modulate the filling channel signals in the same optical wavelength in the optical fiber channel transmission, the receiver with the same code sequence related to receive, that is, to recover the original channel signal. The advantages of OCDM are that it can greatly improve network performance, enhance network communication capacity and system signal to noise ratio, enhance system secrecy and increase network flexibility.