Wavelength selective switch with reduced chromatic dispersion and polarization-dependent loss

Abstract

A reduced polarization-dependent loss optical device utilizing two or more dispersive elements or a single dispersive element and a turning mirror, wherein the optical signal makes two passes through said single dispersive element when reflected from said turning mirror, and wherein the two or more dispersive elements or double pass single dispersive element has lower dispersion compared to a functionally equivalent single dispersive element, resulting in lower polarization dependent loss, reduced chromatic dispersion and increased wavelength dispersion. Moreover, a wavelength selective switch incorporating the optical device utilizing aperture-shared optics and functionally distinct planes of operation that enables high fiber port counts, such as 1×41, and multiplicative expansion, such as to 1×83 or 1×145, by utilizing elements optimized for performance in one of the functionally distinct planes of operation without affecting the other plane.

Description

PRIORITY CLAIM TO RELATED US APPLICATIONS[0001]To the full extent permitted by law, the present United States Non-Provisional patent application claims priority to and the full benefit of United States Provisional patent application entitled “Wavelength Selective Switch Having Distinct Planes of Operations”, filed on Feb. 28, 2008, having assigned Ser. No. 61 / 067,635 and United States patent application entitled “Wavelength Selective Switch Having Distinct Planes of Operations”, filed on Jul. 23, 2008, having assigned Ser. No. 12 / 220,356, incorporated entirely herein by reference.TECHNICAL FIELD[0002]The present invention relates generally to optical communications, and more specifically relates to wavelength division multiplexing.BACKGROUND OF THE INVENTION[0003]Modern communications networks are increasingly based on silica optical fiber which offers very wide bandwidth within several spectral wavelength bands. At the transmitter end of a typical point-to-point fiber optic communi...

AI Technical Summary

Benefits of technology

[0014]Briefly described in a preferred embodiment, the present invention overcomes the above-mentioned disadvantages and meets the recognized need for such a system by providing a wavelength selective switch (WSS) with reduced chromatic dispersion and / or low polarization-dependent loss and utilizing aperture-shared optics to increase the fiber port capacity and optical performance of the WSS, while simultaneously reducing the performance requirements for individual components thereof, wherein optimization of optical performance in functionally distinct orthogonal planes is enabled.

Problems solved by technology

For very long links, the optical signal risks becoming excessively distorted due to fiber-related impairments, such as, chromatic and polarization dispersion, and by noise limitations of the amplifiers, and may be reconstituted by detecting and re-launching the signal back into the fiber.

However, the same issues about signal degradation and OEO regeneration exist for WDM as with non-WDM fiber links.

The expense of OEO regeneration is compounded by the large number of wavelengths present in WDM systems.

Modern fiber optic networks are evolving to be much more complicated than the simple point-to-point “long haul” systems described above.

However, the desire to switch fiber optic signals while still in their optical format, thereby avoiding expensive OEO regeneration to the largest extent possible, presents a new challenge to the switching problem.

This replication of expensive OEO components is currently slowing the implementation of highly interconnected mesh WDM systems employing a large number of wavelengths.

As fiber port counts increase, however, the size of the optics of such WDM wavelength selective switches grows quickly.

For example, where a MEMS mirror array is employed, the increased size of the device requires a greater tilt angle, increasing the cost of the MEMS mirror array, and increasing the defect rate.

Such dedicated elements increase costs by virtue of their number, but also typically require extremely high performance characteristics and low tolerances, which, likewise, increases costs.

Therefore, it is readily apparent that there is a need for an improved WDM wavelength selective switch that allows for increased fiber port counts without substantially increasing the size of the device, and at the same time, reduces the performance requirements for the components thereof, including the switching elements.

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