Photonic Integrated Circuit Using Segmented Wavelength Combs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical transceivers face challenges in optimizing total bandwidth, bandwidth per fiber, linear bandwidth density, and energy efficiency due to limitations in designing and fabricating dense-wavelength-division-multiplexed (DWDM) and coarse-wavelength-division-multiplexed (CWDM) systems, particularly in increasing wavelength-channel count and spectral density while minimizing crosstalk and optical loss.
Innovation Solution
A photonic integrated circuit (PIC) architecture that combines DWDM and CWDM concepts, using multiple signal-generator sections with hybrid-integrated multiwavelength lasers and ring-resonator-based modulators to create composite DWDM signals, and a receiver section with polarization splitters and demultiplexers to separate wavelength channels effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of wavelength channels is increased to expand aggregate bandwidth, then the total spectral bandwidth must be widened, but this requires laser sources with broader gain bandwidth which becomes difficult or impossible to achieve
Solution Approach 1:
The system segments the wavelength channels into multiple wavelength combs, where each comb is generated by a separate laser source with a manageable spectral range. This allows the overall system to achieve high wavelength-channel count without requiring any single laser to cover the entire bandwidth, thus resolving the contradiction between quantity of channels and laser adaptability.
2Quantity of substance
If ring resonator modulators are added to support more wavelength channels, then the spectral bandwidth increases, but the free spectral range of each resonator must be reduced requiring smaller ring radii that become difficult to fabricate
Solution Approach 1:
The system segments the wavelength channels into multiple combs that can be independently managed. Each ring resonator modulator only needs to handle a subset of wavelengths within its fabrication-capable FSR, rather than attempting to modulate all channels across the entire spectral bandwidth. This segmentation allows practical fabrication while achieving high channel count systemically.
3Quantity of substance
If wavelength-channel spacing is reduced to increase spectral density, then more channels fit in the same bandwidth, but crosstalk between adjacent channels increases
Solution Approach 1:
The system uses wavelength-selective filters as intermediary elements between adjacent wavelength channels. These filters provide isolation between closely-spaced channels, allowing high spectral density to be achieved without excessive crosstalk. The filters act as mediators that enable tight channel spacing while maintaining signal integrity through selective wavelength transmission.
4Productivity
If DWDM is used to achieve spectrally efficient links, then bandwidth is optimized, but wavelength-selective filters become more difficult to design and fabricate
Solution Approach 1:
The system segments the complex wavelength-selective filtering function into multiple simpler filter stages, each handling a subset of wavelengths or a specific comb. This segmentation reduces the complexity of individual filter designs while maintaining the overall spectral efficiency of DWDM, as each filter only needs to handle a manageable portion of the total spectral bandwidth.
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 combined architecture achieves high aggregate bandwidth with sufficient wavelength spacing for high-speed modulation and multiplexing, reducing crosstalk and optical loss, while enabling efficient wavelength separation and detection.
Implementation Method 1
A ring-resonator-based spectral filter or modulator comprises multiple ring resonator elements, each optically coupled to a common bus waveguide for light of a different wavelength
Implementation Method 2
DWDM also enables the use of novel wavelength-dependent devices, such as ring-resonator-based modulators/filters that have repeat modes located several nm away from the intended spectral location
Implementation Method 3
A transmitter section includes a first plurality of signal-generator sections integrated on a first substrate, and a first planar-lightwave circuit comprising a first optical element that is optically coupled with the first plurality of signal-generator sections
Data Source
AI summary
The present disclosure is directed toward architectures that combine DWDM and CWDM concepts in a single PIC. Transmitter stages in accordance with the present disclosure include a plurality of multiwavelength lasers having regions of separately grown epitaxial material whose gain peaks are centered at different wavelengths. Each laser launches a wavelength comb comprising a plurality of wavelength signals into a PLC, where the wavelengths within each wavelength comb are separated by a wavelength spacing that is smaller than that between adjacent wavelength combs. In some embodiments, the PLC includes modulator banks for encoding data on the wavelength signals and combining them to produce a composite DWDM output signal. In some embodiments, a receiver stage is included for demultiplexing a composite DWDM input signal and detecting each wavelength channel within it. In some embodiments, the receiver stage employs polarization-diversity techniques to enable it to operate on unpolarized/randomly polarized input signals.