Optical Demultiplexer Using cAWG and Gate Switches
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Solution Overview
Problem
In optical transmission systems, active filters such as T filters and WSSs experience aging deterioration or failure, leading to shifts or narrowing of transmission bands, causing variations in transmission wavelengths and resulting in communication interruptions.
Innovation Solution
An optical demultiplexer comprising optical gate switches and a cyclic arrayed waveguide grating (cAWG) is used to demultiplex multiplexed optical signals, eliminating variations in transmission wavelength and ensuring proper transmission of target wavelengths by performing simple on/off operations and passive demultiplexing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If active filters (T filters or WSS) are used for wavelength selection, then the network achieves flexibility and colorless operation, but transmission wavelength variation occurs due to aging deterioration
Solution Approach 1:
The invention segments the wavelength selection function into two independent parts: a passive cAWG for wavelength demultiplexing and a simple optical gate switch for signal routing. This segmentation eliminates the need for complex active filtering while maintaining network flexibility through the gate switch's on/off control capability.
Solution Approach 2:
The invention introduces a cyclic arrayed waveguide grating (cAWG) as an intermediary device between the optical coupler and the optical gate switch. The cAWG passively demultiplexes wavelengths without active control, providing stable wavelength separation while the gate switch provides simple binary control for network flexibility.
2Ease of operation
If active filters are used for demultiplexing, then wavelength routing is achieved, but device complexity increases due to aging and maintenance requirements
Solution Approach 1:
The invention replaces expensive, maintenance-prone active filters with a combination of a passive cAWG and a simple optical gate switch. The gate switch requires only binary on/off control without complex filtering mechanisms, significantly reducing device complexity and maintenance requirements while maintaining wavelength routing capability.
3Adaptability or versatility
If T filters or WSS are used for wavelength selection, then communication nodes can operate colorlessly, but communication interruptions occur due to transmission band shifts
Solution Approach 1:
The invention uses a passive cAWG with fixed, pre-determined wavelength routing paths that are immune to aging effects. This provides beforehand cushioning against transmission band shifts by eliminating the active filtering mechanisms that are prone to deterioration, ensuring continuous reliable operation while maintaining colorless network capability through the gate switch.
Data Source
AI summary
An optical demultiplexer 40 includes: a plurality of optical gate switches 41a to 41n configured to transmit, when being turned on, and to block, when being turned off, a multiplexed optical signal obtained by multiplexing optical signals of a plurality of wavelengths by time-division multiplexing or wavelength-division multiplexing in addition to time-division multiplexing; and a cAWG 42 including a plurality of input ports and a plurality of output ports and configured to input the multiplexed optical signal transmitted through the optical gate switches 41a to 41n from the plurality of input ports, demultiplex the input multiplexed optical signal for each wavelength, and cycle and output the demultiplexed optical signals from the plurality of output ports in a predetermined order.