Multi-pole Optical Signal Switch Hitless WDM Routing
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Solution Overview
Problem
Existing optical communication systems lack a simple, multi-pole, multi-way wavelength selective switch capable of routing WDM signals from any input port to any output port in a hitless manner, with add and drop functionalities, and are limited by the complexity and height of current switch structures.
Innovation Solution
A fiber-optical wavelength selective switch using birefringent crystals to convert optical signals into polarized beams, which are laterally expanded and spatially dispersed, then steered using a pixilated beam steering element to direct different wavelengths to specific output ports, with a polarization rotation device controlling transmission, attenuation, or blocking, and a beam steering element ensuring hitless switching by preventing coupling into undesired ports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a multi-pole, multi-way wavelength selective switch is implemented, then routing capability from any input port to any output port is improved, but device complexity increases
Solution Approach 1:
The switch is divided into multiple independent wavelength channels, each handled by a dedicated polarization rotation pixel. This segmentation allows the complex multi-pole routing function to be decomposed into simpler single-channel operations that can be performed in parallel, achieving high adaptability without proportionally increasing overall system complexity
Solution Approach 2:
The polarization rotation device serves multiple functions: it rotates polarization for wavelength selection, controls transmission/attenuation, and enables blocking. This multi-functionality reduces the need for separate components for each function, thereby managing device complexity while achieving versatile routing capability
2Measurement precision
If wavelength resolution is improved, then signal separation precision is improved, but switch height increases
Solution Approach 1:
The patent transitions from traditional vertical stacking of optical components to a lateral arrangement where wavelength dispersion occurs in a plane perpendicular to the beam propagation direction. This dimensional change allows high wavelength resolution through spatial dispersion while keeping the switch height compact, as the dispersion plane extends laterally rather than vertically
3Reliability
If hitless switching is achieved, then signal integrity is improved, but device complexity increases
Solution Approach 1:
The polarization rotation is applied to the beam before it reaches the output ports during the switching process. This preliminary action ensures that the beam is properly oriented and isolated from undesired ports before final output, preventing spurious signals without requiring complex real-time control mechanisms during the switching transition
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a compact, efficient, and high-resolution wavelength selective switch that can route WDM signals from any input port to any output port without spurious signals, enabling scalable and cost-effective optical communication systems with improved wavelength resolution and reduced switch height.
Implementation Method 1
The switch uses a minimum of components, and can thus be economically constructed for large scale use in such systems. The switch structure can also be used as a wavelength selective variable optical attenuator for any of the transfer routes therethrough.
Implementation Method 2
The wavelength dispersion is preferably performed by a diffraction grating
Implementation Method 3
A polarization rotation device, such as a liquid crystal polarization modulator, pixilated along the wavelength dispersive direction such that each pixel operates on a separate wavelength channel, is operative to rotate the polarization of the light signal passing through each pixel, according to the control voltage applied to the pixel
Implementation Method 4
an input optical signal is spatially wavelength-dispersed and polarization-split in two preferably perpendicular planes. The wavelength dispersion is preferably performed by a diffraction grating, and the polarization-splitting by a polarized beam splitter
Data Source
AI summary
An optical switch having multiple input and output ports directs any number of WDM signals, each arriving at a respective input port, to any one of the output ports. The optical switch includes an array of LC pixels, each positioned to receive a WDM signal transmitted through one of the ports, and an array of reflective elements, each associated with one of the LC pixels. The LC pixels are controlled to cause a WDM signal incident thereon to attain an attenuation state while an output of the WDM signal is being switched by an associated reflective element, such that when an output for a WDM signal is switched from a first port to a second port, the switching can be performed in a hitless manner.