Multi-Port Wavelength Selective Switch Path Ambiguity
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Solution Overview
Problem
Existing wavelength-dependent optical switches with multiple input and output ports face ambiguity in path selection, leading to undesired coupling of signals with the same wavelength, which is unacceptable in optical communication networks.
Innovation Solution
Configuring input ports at the extremities of the fiber array ensures that only one input signal of a given wavelength can be switched to its desired output port, while signals of the same wavelength from the second input port are blocked, using a beam steering mechanism that directs different wavelength signals to different steering elements for appropriate output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If input ports are configured at arbitrary positions in the fiber array, then the router can provide flexible path selection, but signals of the same wavelength from different input ports may be coupled to undesired output ports causing path ambiguity
Solution Approach 1:
The patent applies asymmetry by positioning the two input ports at symmetric extremities (first and last positions) of the fiber array, which creates an asymmetric switching behavior: signals from one input port can be switched to multiple output ports while signals from the other input port are blocked, thereby eliminating path ambiguity for like-wavelength signals while maintaining flexible path selection capability
2Device complexity
If a single beam steering element is used to switch signals from multiple input ports, then device complexity is reduced, but path ambiguity occurs where like-wavelength signals from different input ports may be directed to different output ports simultaneously
Solution Approach 1:
The patent changes the spatial parameter (position) of input ports to extremities of the fiber array, which fundamentally alters the switching behavior of the single beam steering element. This parameter change ensures that when the beam steering element directs signals from one input port to various output ports, signals of the same wavelength from the other input port are geometrically blocked from reaching any output port, thus maintaining switching path uniqueness without requiring additional beam steering elements
3Reliability
If input ports are positioned at extremities of the fiber array, then path ambiguity is eliminated ensuring single-valued transfer function, but the angular deviation required of the beam steering element increases
Solution Approach 1:
The patent exploits the spatial dimension of the fiber array by positioning input ports at extremities, which creates a geometric blocking effect in the optical path dimension. This dimensional arrangement ensures that the beam from one extremity input port, when steered to various output ports, geometrically blocks the beam path from the other extremity input port, thereby eliminating path ambiguity while accepting increased angular deviation requirements
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
This configuration ensures a single-valued transfer function, preventing simultaneous switching of like-wavelength signals to different output ports, thereby maintaining signal integrity and reducing the need for additional switches in optical communication networks.
Implementation Method 1
The wavelength dispersion may preferably be performed by a diffraction grating
Implementation Method 2
the polarization-splitting by a polarized beam splitter
Implementation Method 3
A polarization rotation device, such as a liquid crystal polarization modulator, pixelated 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
using beam steering elements which can be either an array of Micro-Electro-Mechanical System (MEMS) components, such as micro-mirrors, or a set of serially disposed liquid crystal arrays and wedge shaped birefringent crystals, which generate different angles of propagation to the beam passing therethrough
Data Source
AI summary
A multi-port wavelength selective switch includes a one dimensional array of input and output ports. The multi-port wavelength selective switch further includes a wavelength dispersive element configured to receive input optical signals from the input ports, and to disperse wavelength components thereof. Additionally, the multi-port wavelength selective switch includes an array of beam steering devices. Each beam steering device is controllable to a position at which the beam steering device directs a wavelength component of an input optical signal received through a first input port to an output port and directs the same wavelength component of an input optical signal received through a second input port away from all of the output ports.