All-optical switch application mechanism and common functions

The biggest advantage of integrated all-optical switches is that they can easily expand to the interconnection, grid-like and ring-like hybrid networks, and grid-shaped networks, which cannot be achieved by other switch products. To reduce operating costs and increase revenue, carriers are keen to adopt new smart optical networks based on new-generation optical devices. These new devices provide new functions and integration of multiple features.

A typical example is an all-optical switching device. All-optical switches have evolved from simple optical mechanical devices to high-speed optical devices with new features. New functions such as dynamic dimmable attenuation and Layer Multicast have been introduced into optical switching devices. The next generation all-optical switch features better performance and richer functions. Performance improvement will build a broad platform for more new applications. It covers from new network technologies to new system integration.

Optical Layer Protection Mechanism

The network protection mechanism used by SDH/SONET, a mainstream transmission technology, has become a de facto industry standard. The new network protection method tends to adopt dual-homing or unprotected Technology in the access network, and uses SDH/SONET self-healing Ring in the Metropolitan Area Network, the main linear protection technologies are or in the long-distance transmission network. However, with the development of optical networks in the intelligent direction, there is an urgent need for a variety of network topologies, such as the ring network, the interconnected ring network, grid-shaped and ring-shaped hybrid network, grid-shaped network) all-new optical layer protection mechanism.

These protection mechanisms should be designed to integrate functions such as switching, multicast, and Attenuation Control. For example, the most popular ring-shaped network protection mechanism is the one-way channel of the secondary fiber for switching the ring UPSR/2) and the two-way line for switching the ring BLSR/2 ). Recently, they have been moved to the optical layer to implement the OCh-DPRING, such as optical channel dedicated channel protection ring, based on the optical usrs) and optical multiplexing segment shared protection ring OMS-SPRING, based on the light BLSR) and other optical layer protection mechanisms.

The integrated all-optical switch makes it easier for the Ring Network to expand to the interconnection, grid-shaped and ring-shaped hybrid networks, and grid-shaped networks. Using a fast all-optical switch with gain control and multicast, You can overlay the virtual protection ring network on the physical grid. The result is faster service recovery, therefore, carriers can provide Differentiated Services.

Dynamic all-optical network

Users' demand for high-bandwidth data services continues to grow. In addition, the recent advances in optical communication technology have promoted the emergence of Dynamic Intelligent Optical Networks. The Intelligent Optical Layer provides a variety of services, such as Channel Dynamic Distribution, optical power monitoring, optical layer protection, and burst light switching. Whether it is an all-optical network or an OEO-based network, the introduction of the new features above enables the DWDM optical network to achieve dynamic wavelength allocation. Their control plane can be built on the network management system, GMPLS, or burst all-optical switch. However, they have similar requirements for optical layer functions.

Dynamic wavelength assignment requires better adaptation to physical layer changes. In the OEO network, the wavelength is eventually connected to each node. This limits the impact of light on each link passing through the wavelength, and allows a simple balanced output power of the transmitter to be achieved on each link ). Therefore, the instantaneous effect in the OEO network mainly affects the optical amplifier. For example, the new wavelength between node D and G will lead to an increase in the optical signal input power of amplifier 1, resulting in a channel gain attenuation of 3 dB. The optical power of the optical amplifier 2 and 3 is reduced by two times, and the receiving power of node F is decreased significantly. Therefore, it will trigger the alarm and Protection Switching of service interruptions. To avoid this problem, the link amplifier should be able to automatically adjust the gain as the input power changes. The integrated optical switch technology is very suitable for the design requirements of such devices.

Obviously, the switching speed is very important. New wavelengths can be provided quickly or gradually. Quick operations will ensure that the optical channel remains stable before the Protection Switching is triggered. The required stability time is almost microseconds related to specific applications), which may be impossible for all-optical devices.

The corresponding power increase of the new wavelength is also relatively slow, and the influence on the established channel is almost negligible. Therefore, the time when the wavelength reaches stable can also be relaxed accordingly. The disadvantage is that establishing a connection takes a long time and increases the complexity of the entire process.

All-optical multicast

Due to the exponential increase in bandwidth demand for applications, a lot of research has been made on the application of multicast in the group exchange network. By extending the Multicast Technology for sub-networks to the optical field, operators can improve the transmission performance of broadband images, high-definition TVs, storage area networks (SAN), and multimedia services. In addition, other benefits can be obtained, such as network optimization to reduce the number of receivers in the network, extending the "virtual" connections between network nodes, wavelength collection, and reducing the number of wavelengths ). This attracts people's interest in Optical Layer Multicast Networks. The Optical Layer Multicast is a light layer connection pointing to multiple points. All-optical multicast refers to the distribution of optical input power among multiple ports of a node.

Optical Splitter

Nowadays, SDH/SONET Ring Networks are widely used in man networks. Therefore, to establish and develop man networks, we must fully consider the existence of large-scale Optical Fiber Ring Networks. This means that the initial deployment of the DWDM technology must be on the Ring Network and the hybrid grid network structure should be used as the overlay network.

Reconfigurable Optical Splitter R-OADM) is a necessary device for deploying a DWDM dynamic system on a ring network. This wavelength reconfiguration feature allows operators to quickly configure the network to quickly generate new revenues. All-optical reconfiguration also makes it easier for the Network to evolve to a more complex lattice ring network or grid network.

The development of all-optical switch provides more light layer functions for R-OADM. For example, an all-optical switch can provide the upstream and downstream functions. Gain control facilitates wavelength reconfiguration, while multicast provides up/down multiplexing. Uplink and downlink are required to configure the wavelength on each other, share the single wavelength bandwidth between nodes, and provide the protection structure.

An all-optical switch has evolved into a multi-functional all-optical device, making many new applications that previously could not be implemented a reality, such as dynamic all-optical network, burst light switching, testing equipment and delay line. We can believe that the new generation network based on these applications will be able to provide more new services at a very low cost.