Symmetric Silicon DFB Laser Power Combining Without Wavelength Tuning
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Solution Overview
Problem
Implementing fixed wavelength silicon photonic lasers in photonic integrated circuits (PICs) is challenging due to calibration issues, power inefficiencies, and process control problems, particularly with silicon-based DFBs, which lack anti-reflectivity coatings and suffer from high loss and reflection, making them incompatible with silicon designs.
Innovation Solution
A silicon photonic symmetric DFB laser architecture that outputs light to two waveguides, using a 2×1 optical combiner for power combining and thermal phase tuners for phase matching, eliminating the need for wavelength adjustment and achieving high power efficiency by utilizing both output ports, thereby reducing calibration costs and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fixed wavelength silicon photonic lasers are implemented in PICs, then control simplicity is improved, but calibration issues and process control problems worsen
Solution Approach 1:
The patent employs asymmetric DFB laser designs where the grating structure is intentionally made asymmetric to eliminate the need for anti-reflectivity coatings on one facet. This asymmetry allows the laser to operate at a fixed wavelength without requiring precise calibration of both facets, thereby maintaining control simplicity while reducing manufacturing precision requirements.
Solution Approach 2:
The patent extracts or removes the requirement for anti-reflectivity coatings by using asymmetric grating designs. By taking out this problematic element, the system achieves fixed wavelength operation without the calibration and process control issues that plague symmetric designs requiring such coatings.
2Ease of manufacture
If silicon-based DFBs without anti-reflectivity coatings are used, then manufacturing simplicity is improved, but optical loss and reflection worsen
Solution Approach 1:
The asymmetric grating design concentrates the optical field distribution such that one facet experiences minimal reflection while the other is optimized for output. This asymmetric field distribution reduces overall optical loss without requiring anti-reflectivity coatings, thus maintaining manufacturing simplicity while improving optical efficiency.
Solution Approach 2:
The patent applies local quality optimization by designing the grating structure with spatially varying properties - the grating parameters change along the laser cavity to locally optimize both reflection suppression and output coupling. This allows different regions of the laser to have different optical characteristics, reducing overall loss without additional coating processes.
3Adaptability or versatility
If tunable lasers with filters are used, then wavelength adaptability is improved, but control complexity and power consumption worsen
Solution Approach 1:
The patent introduces dynamic control through thermal phase tuners that can adjust the laser wavelength by changing the refractive index via temperature control. This dynamic mechanism provides wavelength adaptability without requiring complex mechanical filter systems, reducing device complexity while maintaining tuning capability.
Solution Approach 2:
The patent changes the operating parameter from mechanical filter positioning to thermal phase control. By using temperature-induced refractive index changes to tune the wavelength, the system achieves adaptability with simpler control electronics and lower power consumption compared to mechanical filter-based tunable lasers.
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 enables high optical mode stability and power efficiency in silicon photonic symmetric DFBs, simplifying laser control and reducing the need for complex calibration, making them suitable for multi-lane transceivers and other applications.
Implementation Method 1
thermal phase tuners for phase matching
Data Source
AI summary
A symmetric distributed feedback (DFB) laser that is integrated in a silicon based photonic integrated circuit can output light from both sides of the symmetric DFB laser onto waveguides. The light in the waveguides can be phase adjusted and combined using an optical coupler. The symmetric DFB laser can generate light and symmetrically output light onto different lanes of a multi-lane transmitter.