DWDM Photonic Integrated Circuit Channel Multiplexing
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Solution Overview
Problem
The increasing complexity and density of integrated circuits require higher bandwidth optical I/O interfaces, which are limited by the fixed free spectral range and minimum channel spacing of silicon-based optical ring modulators, leading to a need for a more efficient use of fiber bandwidth to reduce the number of optical fibers and photonic I/O cells needed.
Innovation Solution
A dense wavelength division and multiplexing (DWDM) scheme is implemented using a photonics integrated circuit with multiple optical modulation circuits, each comprising channel de-interleavers, micro-ring modulator arrays, and optical interleavers to separate and modulate optical streams with increased channel spacing, allowing for more optical channels on a single fiber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon-based optical ring modulators with fixed free spectral range and minimum channel spacing are used, then the modulators can be manufactured with standard processes, but the number of optical channels that can be supported within a given fiber is limited
Solution Approach 1:
The patent divides the optical channels into multiple groups and uses multiple sets of micro-ring modulators, each set handling a specific subset of channels. This segmentation allows each modulator to operate with appropriate channel spacing while the system as a whole supports higher channel density through coordinated operation of multiple modulator sets.
Solution Approach 2:
The patent employs dynamic tuning mechanisms that allow the free spectral range and channel spacing to be adjusted in real-time. By making the modulator characteristics variable rather than fixed, the system can adapt to different channel spacing requirements and optimize performance for varying bandwidth demands.
2Productivity
If the number of optical channels on a single fiber is increased beyond traditional limits, then fiber bandwidth efficiency is improved, but cross-talk and signal degradation increase
Solution Approach 1:
The patent segments the optical spectrum into distinct channels and uses multiple micro-ring modulator sets, each tuned to specific resonance frequencies. This segmentation isolates adjacent channels in the frequency domain, reducing spectral overlap and cross-talk even as the total number of channels increases.
Solution Approach 2:
The patent dynamically adjusts operational parameters including free spectral range, channel spacing, and resonance frequencies of the micro-ring modulators. By optimizing these parameters in real-time, the system maintains signal quality and minimizes cross-talk while maximizing the number of supported channels.
3Power
If multiple optical fibers and photonic I/O cells are used to meet bandwidth demands, then the required bandwidth can be achieved, but the device complexity and package size increase
Solution Approach 1:
The patent merges multiple optical channels onto a single fiber by using wavelength-division multiplexing techniques. Multiple micro-ring modulator sets work together to modulate different channels on the same fiber, effectively combining the capacity of what would traditionally require multiple separate fibers into a single fiber interface.
Solution Approach 2:
The patent creates a universal optical interface that can handle multiple channels simultaneously through a single photonic I/O cell. The micro-ring modulator arrays are configured to support multiple wavelengths and channel configurations, making the interface multi-functional and eliminating the need for separate dedicated channels for each function.
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 approach increases the number of optical channels on a fiber beyond traditional limits, reducing the number of fibers and photonic I/O cells required, while maintaining minimal cross-talk and signal degradation, thus enhancing bandwidth efficiency.
Implementation Method 1
silicon-based optical ring modulators to modulate data for the optical I/O interfaces
Implementation Method 2
channel de-interleavers configured to separate the optical input source into first and second optical streams
Data Source
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Figure 2B
AI summary
An apparatus and method for generating a dense wavelength division and multiplexing (DWDM) optical stream in a photonic integrated circuit (PIC) is disclosed. An optical input source including a number (N) of optical channels (wavelengths) may be separated (de-interleaved) into multiple optical streams, each including a corresponding subset of the optical channels of the optical input source. Each of the multiple split optical streams may be modulated with an associated set of data streams by silicon-based micro-ring modulators to generate a corresponding modulated optical stream. A first pair of the modulated optical streams may be combined (interleaved) to generate a first optical output stream including N/2 modulated optical channels, and a second pair of the modulated optical streams may be combined (interleaved) to generate a second optical output stream including N/2 modulated optical channels. The channel spacing of the first and second optical output streams may be twice the channel spacing of the optical input source.