Wavelength Multiplexing Unit With Tunable Band-Limiting Filters
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Solution Overview
Problem
Current wavelength multiplexing systems with wavelength tunable transmitters require manual reconnection to wavelength multiplexers due to fixed port-wavelength relationships, complicating management and increasing costs, especially when using large-scaled optical matrix switches.
Innovation Solution
Incorporating band-limiting filters with center wavelength tunability between transmitters and wavelength multiplexers, allowing remote wavelength adjustment and connection, using passive star couplers and bandpass filters like optical fiber Bragg gratings, Mach-Zehnder interferometers, or ring resonators to eliminate out-of-band light and enable wavelength multiplexing with any input wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If wavelength tunable transmitters are used with fixed port-wavelength relationships in wavelength multiplexers, then wavelength flexibility is improved, but system complexity and operational cost increase due to manual reconnection requirements
Solution Approach 1:
The patent introduces band-limiting filters as intermediary components between transmitters and the wavelength multiplexer. These filters act as mediators that condition the optical signals by limiting their bandwidth before multiplexing, enabling wavelength tunable transmitters to work with a simplified multiplexer that has fixed port-wavelength relationships, thus avoiding the need for complex optical matrix switches
Solution Approach 2:
The patent segments the wavelength multiplexing system into distinct functional modules: transmitters with band-limiting filters, wavelength multiplexer, and optical amplifier. By separating the bandwidth limiting function from the multiplexing function, the system achieves wavelength flexibility without requiring complex interconnections, as each module operates independently with well-defined interfaces
2Adaptability or versatility
If large-scaled optical matrix switches are used to enable remote switching, then wavelength adaptability is improved, but device complexity and cost increase significantly
Solution Approach 1:
Band-limiting filters serve as intermediary devices that enable remote wavelength switching without requiring optical matrix switches. By conditioning signals at the transmitter side, the system achieves flexible wavelength assignment through simple electronic control of filter tuning, eliminating the need for complex optical switching matrices
Solution Approach 2:
The patent replaces the mechanical/optical complexity of matrix switches with electronically controlled band-limiting filters. The filtering function is controlled through electrical signals that adjust the filter characteristics, substituting complex optical switching mechanics with simpler electronic control mechanisms
3Productivity
If band-limiting filters are added to each transmitter, then spectral efficiency is improved by eliminating out-of-band light, but device complexity increases
Solution Approach 1:
The band-limiting filters perform preliminary bandwidth restriction on optical signals before they enter the wavelength multiplexer. By pre-conditioning the signals to contain only necessary frequency components, the system achieves high spectral efficiency and prevents out-of-band interference, while the added complexity is minimal compared to alternative solutions
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
Enables remote and cost-effective switching of wavelength tunable transmitters with the wavelength multiplexer, reducing unnecessary light interference and improving spectral efficiency by filtering before multiplexing, thus simplifying the system structure and reducing operational costs.
Implementation Method 1
a plurality of band-limiting filters provided to each of those transmitters, which have functions of eliminating light out of assigned bands from the signal lights outputted from the transmitters
Implementation Method 2
a wavelength multiplexer including a plurality of ports capable of inputting lights of any wavelengths to be targets of wavelength multiplexing, which inputs a plurality of signal lights from which the light out of the bands are eliminated by the plurality of band-limiting filters via the plurality of ports, respectively, and multiplexes those signal lights
Data Source
AI summary
When using a wavelength multiplexing unit of a wavelength multiplexing optical transmission system in which a wavelength tunable type optical transmitter and a wavelength multiplexer having no wavelength selectivity are combined, undesired light that is not supposed to be flown into a wavelength channel may be mixed therein. A wavelength multiplexing unit includes: transmitters having functions of outputting signal lights of different wavelengths from each other and changing the wavelengths; band-limiting filters provided to each of the transmitters, which have functions of eliminating the lights out of bands from the signal lights outputted from the transmitters, and changing the center wavelengths of the bands; and a wavelength multiplexer including ports capable of inputting the lights of any wavelengths, which inputs signal lights from which the light out of the bands is eliminated by the band-limiting filters and multiplexes the signal lights.