Present situation and development prospect of optical switch in communication system

Summary

Optical switch is an important optical passive device, which can break and switch the light signal in optical network system. Optical switches are widely used in optical division/interpolation Multiplexing (OADM), Time Division Multiplexing (TDM), Wavelength Division multiplexing (WDM). Optical switch has become the focus of major communication companies and research units for its high speed, high stability and low crosstalk. Optical switch has a broad market prospects, is one of the most promising optical passive devices.

First, optical switch and all optical network

In recent years, with the rapid development of tele-communication and computer communication, especially the explosive rise of internet/intranet business, traditional transmission system based on electronic field has been unable to meet the increasing business needs. Dense wavelength division multiplexing (DWDM) technology uses the low loss window of single-mode fiber to transmit multi-channel wavelength carrier simultaneously in one fiber, and uses erbium-doped fiber amplifier (EDFA) to replace the traditional photoelectric relay system. Not only increase the capacity of the optical fiber, but also get rid of the single fiber transmission rate constraints caused by "electronic bottleneck" in the process of photoelectric conversion. Therefore, it is considered as an effective way to improve the capacity of optical fiber communication, as shown in Figure 1.

As we see in Figure 2, the optical crossover connector (OXC) and the optical/lower multiplexer (OADM) are the key to all optical networks. Oadm and OXC can manage signals at any wavelength to make fuller use of bandwidth. Furthermore, the topological structure of the ring network enhances the reliability of WDM devices and the survivability of the data.

The optical crossover matrix is the core of OXC, which requires non-blocking, low latency, broadband, and high reliability, as well as one-way, bidirectional, and broadcast functions, as shown in Figure 3. The optical switch is the most basic device in optical switching and optical interconnection, and its performance and price will directly affect the commercial process of OXC system.