Tunable add/drop optical filter

Abstract

In all-optical networks, optical switching and routing become the most important issues for interconnecting the transport network layers. This invention describes a novel tunable optical add / drop filter for the all-optical wavelength-division-multiplexing (WDM) network applications. This filter can add or drop part of the high transmission capacity signals of a WDM link. It can be used to decentralized access point in the access network or as small core network node to realizing branching points in the network topology. It works in both wavelength and space domains. It has the advantages of: 1) High throughput and low voltage operation; 2) Wide tuning range and therefore, high channel capacity; 3) High isolation and high directivity between input and output ports; 4) Compact device packaging is possible as compares to the conventional grating and mechanical switching type of add / drop filter; 5) Multiple ports add / drop tunable filters can be realized with this invention to interconnect multiple WDM networks. This novel add / drop filter can be used in various WDM topologies. It enhances the performance of the conventional tunable filter by re-routing the rejected wavelengths back to network, which not only save the precious optical energy, but also cut down the return loss of the device.

Description

FIELD OF THE INVENTIONIn this invention, a tunable add / drop filter for the wavelength-division-multiplexing (WDM) network applications is described. This filter can add or drop part of the high transmission capacity signals of a WDM link.BACKGROUND OF THE INVENTIONThe communication environment is evolving towards increasingly heterogeneous but interconnected networks. The growth of demand for existing services and the introduction of new advanced services is expected to create a large increase of traffic flow in the near future. The current evolution of telecommunication network is led by asynchronous and synchronous transfer modes (Asynchronous Transfer Mode(ATM), Synchronous Optical Network (SONET), Synchronous Digital Hierarchy (SDH)), which require primarily electronic technologies for processing and switching. Although the necessary hardware building blocks are available to design wide area networks, complex .[.issue arises with.]. .Iadd.issues arise with .Iaddend.the managemen...

AI Technical Summary

Benefits of technology

The present invention includes a tunable add/drop filter that utilizes the unique operational characteristics of a non-reciprocal optical setup and a reciprocal optical setup for wavelength re-routing, and a tunable filter for wavelength selection. The non-reciprocal optical setup provides the functionality for

Problems solved by technology

Although the necessary hardware building blocks are available to design wide area networks, complex .

In all-optical networks, optical switching and routing become the most important issues for interconnecting the transport network layers.

The structure is complicated and the interconnections are difficult.

This filter provides the advantage of arbitrary channel arrangement, but still suffers a costly 6 dB optical coupling loss, because of the two array waveguide grating demultiplexers used in the structure.

[.the undesirable feature of the broadcast star, the splitting loss can be very high when the users number is large..].

.Iadd.an undesirable feature of the broadcast star is that splitting losses can be very high when the number of users is large..Iaddend.

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