BPLC Wavelength Selective Switch Eliminates Depolarizer
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Solution Overview
Problem
Conventional wavelength selective switches based on Liquid Crystal on Silicon (LCOS) suffer from polarization dependence, increasing complexity and insertion loss, which necessitates the use of a depolarization device, thereby raising costs and complexity in optical communication systems.
Innovation Solution
A wavelength selective switch utilizing a Blue Phase Liquid Crystal (BPLC) device as a spatial light modulator, which eliminates the need for a depolarization device by providing polarization-independent phase modulation, simplifying the optical path and reducing insertion loss and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional LCOS with nematic phase liquid crystal material is used, then wavelength selection can be realized, but polarization dependence increases, requiring additional depolarization devices that increase device complexity and insertion loss
Solution Approach 1:
The patent changes the material parameter from nematic phase liquid crystal to Blue Phase Liquid Crystal (BPLC), which fundamentally alters the optical properties. BPLC exhibits isotropic optical characteristics that eliminate polarization dependence, allowing the system to achieve wavelength selection without requiring additional depolarization devices, thus reducing device complexity while maintaining operational capability
Solution Approach 2:
By using BPLC material that inherently provides polarization-independent operation, the patent eliminates the need for additional depolarization devices. This substitution removes unnecessary components from the optical path, reducing both device complexity and insertion loss while maintaining the wavelength selection function
2Reliability
If a depolarization device is added to eliminate polarization dependence, then polarization-independent operation is achieved, but insertion loss increases by about 0.5 dB and cost increases
Solution Approach 1:
The patent extracts and removes the depolarization device from the optical path by using BPLC material that inherently provides polarization-independent operation. This elimination of the separate depolarization component directly reduces insertion loss (by approximately 0.5 dB as stated in the patent) while maintaining the reliability benefit of polarization-independent operation
Solution Approach 2:
Changing the liquid crystal material parameter from nematic phase to Blue Phase fundamentally alters the optical interaction characteristics. BPLC's isotropic nature provides inherent polarization independence, eliminating the need for energy-lossy depolarization devices while maintaining reliable polarization-independent wavelength selection
3Reliability
If a depolarization device is disposed in the optical path, then polarization dependence is eliminated, but the cost of the wavelength selective switch increases
Solution Approach 1:
The patent removes the depolarization device from the system architecture by using BPLC material that provides inherent polarization independence. This extraction of the unnecessary component directly reduces manufacturing cost while maintaining the reliability advantage of polarization-independent operation
Solution Approach 2:
By substituting the expensive depolarization device with a simplified BPLC-based approach, the patent achieves the same polarization independence function at lower cost. The BPLC material's inherent properties eliminate the need for additional expensive components, reducing overall manufacturing cost while maintaining reliability
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 BPLC-based wavelength selective switch achieves polarization-independent modulation, reducing insertion loss, polarization mode dispersion, and polarization-dependent loss, while lowering costs and enhancing the speed of wavelength selection.
Implementation Method 1
a BPLC device and configured to separate at least one optical signal from the light beam through the BPLC device
Implementation Method 2
LCOS is a spatial light modulation device, which controls a phase of each liquid crystal cell through a voltage to adjust the wavefront of an incident light
Implementation Method 3
controls a phase of each liquid crystal cell through a voltage to adjust the wavefront of an incident light, so that a direction of the incident light is deflected
Implementation Method 4
separate at least one optical signal from the light beam through the BPLC device
Data Source
AI summary
A wavelength selective switch and a wavelength selection method are provided. The wavelength selective switch comprises an input port, through which a light beam, including a plurality of optical signals having different wavelengths, is incident; a wavelength separation apparatus, including a Blue Phase Liquid Crystal (BPLC) device and configured to separate at least one optical signal from the light beam through the BPLC device; and at least one output port, configured to output the at least one optical signal separated by the wavelength separation apparatus respectively. With the wavelength selective switch and the wavelength selection method, a polarization-independent phase modulation can be realized without a depolarization device disposed in an optical path, which thereby simplifies an optical path, reduces an insertion loss, and lowers costs of the wavelength selective switch and even the entire optical communication system.