Multi-way Wavelength Selective Switch Using Pixelated LC Steering
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Solution Overview
Problem
Existing optical switches are limited to 2 x 2 configurations and lack multi-pole, multi-way wavelength selective switch structures with add and drop functionalities for channel routing applications in optical communication systems.
Innovation Solution
A new fiber-optical, multi-way wavelength selective switch structure using birefringent crystals for polarization conversion, anamorphic prisms for lateral expansion, and a diffraction grating for spatial dispersion, combined with a pixilated liquid crystal polarization rotation and beam steering elements to direct wavelength components to specific output ports, enabling hit-less switching with reduced switch height and increased wavelength resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional wavelength selective switches are used, then wavelength selective switching is achieved, but the device is limited to 2x2 configurations and lacks multi-pole multi-way functionality
Solution Approach 1:
The optical signal is segmented by wavelength using a diffraction grating that spatially disperses different wavelength components in the horizontal direction. Each wavelength channel is then independently processed by pixelated liquid crystal elements arranged in a grid, enabling multi-pole multi-way switching through segmented wavelength-specific control
Solution Approach 2:
The invention transitions from conventional 2x2 switching to multi-pole multi-way switching by adding spatial dimensions. Beam steering elements deflect wavelengths in the vertical direction while polarization rotation controls transmission vs. reflection, creating a two-dimensional switching matrix that enables routing between multiple input and output ports simultaneously
2Adaptability or versatility
If conventional optical switches are used, then switching function is provided, but add and drop functionalities are not available
Solution Approach 1:
The pixelated liquid crystal switch array provides universal control capability for multiple switching functions including cross-connect, add, and drop operations. By programming different patterns of pixel activation, the same physical device can perform various channel routing functions, making the system multi-functional without requiring separate dedicated components for each function
3Measurement precision
If wavelength dispersion is performed without lateral expansion, then device structure is simpler, but wavelength resolution is reduced
Solution Approach 1:
Lateral expansion of the optical beam is performed preliminarily in the horizontal direction before the light reaches the diffraction grating. This pre-expansion increases the spatial separation between different wavelength components after dispersion, thereby improving wavelength resolution and enabling more precise wavelength-selective switching without requiring additional complex optical elements
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, economically viable, multi-way wavelength selective switch capable of channel routing and blocking with enhanced wavelength resolution, suitable for large-scale use in optical communication systems, and supports add and drop functionalities.
Implementation Method 1
The switch structure utilizes conversion, preferably by the use of birefringent crystals, of optical signals input to any port of the switch, to light beams having a defined polarization, preferably linear
Implementation Method 2
This lateral expansion is preferably performed by means of a pair of anamorphic prisms
Implementation Method 3
The beam is then spatially wavelength-dispersed in the same predetermined plane as that of the beam expansion, preferably by means of a diffraction grating
Implementation Method 4
a liquid crystal (LC) cell pixelated along the wavelength dispersive direction, such that each pixel operates on a separate wavelength. When the appropriate control voltage is applied to a pixel, the polarization of the light signal passing through that pixel is rotated
Implementation Method 5
a pixilated beam steering element disposed such that the at least one wavelength component passing through a pixel of the polarization element is steered towards its desired output port
Data Source
Figure 1~2
Figure 3
Figure 4A~4B
AI summary
A fiber-optical, wavelength selective switch, especially for channel routing with equalization and blocking applications. The input signals are converted to light beams having predefined polarizations (41). The beams are then laterally expanded (43), and then undergo spatial dispersion in the beam expansion plane. The different wavelength components are directed through a polarization rotation device, pixilated along the wavelength dispersion direction such that each pixel operates on a separate wavelength. Each beam is passed into a pixilated beam steering array (48), for directing each wavelength to a desired output port. The beam steering devices can be MEMS-based or Liquid crystal-based, or an LCOS array. When the appropriate voltage is applied to a pixel and its associated beam steering element, the polarization of the light passing through the pixel is rotated and the beam steered to couple to the selected output port.