Variable Current Channel DFB Laser for Efficient Carrier Injection
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Solution Overview
Problem
Lasers used in digital communications face inefficiencies due to mismatched electrical charge injection and photon density within the optical cavity, leading to wasted power and spectral impurity, which affects bit-error rates and operational costs.
Innovation Solution
Implementing a variable current channel and variable mesa structure in DFB lasers to modulate current and resistance along the cavity, matching charge injection to photon density and mitigating thermal non-uniformities, thereby enhancing efficiency and spectral purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If uniform current injection is applied across the laser cavity, then the device structure is simple, but electrical charge injection does not match photon density distribution leading to power waste
Solution Approach 1:
The current channel width is varied along the longitudinal direction of the laser cavity, creating different current injection characteristics in different regions. The wider current channel in the first region and narrower current channel in the second region match the local photon density distribution, enabling efficient electrical-to-optical conversion at each location while maintaining overall device efficiency.
2Power
If high current is injected to increase optical power, then sufficient power is provided for communication link, but thermal non-uniformities increase reducing spectral purity
Solution Approach 1:
The variable current channel structure distributes current injection non-uniformly along the cavity, with higher current density in regions requiring more optical power and lower current density in regions where photon density is already sufficient. This localized current modulation achieves the required total optical output power while preventing excessive localized heating, thereby maintaining thermal uniformity and spectral purity.
3Use of energy by moving object
If current channel width is constant, then manufacturing is easier, but charge injection does not match photon density variation along cavity length
Solution Approach 1:
The current channel width is designed to vary along the longitudinal direction of the laser cavity, with a wider width in the first region and a narrower width in the second region. This spatial variation in current channel dimensions matches the photon density distribution, enabling efficient carrier injection where needed while maintaining manufacturability through standard semiconductor fabrication techniques.
4Reliability
If external optical feedback is present, then laser operation may be disrupted, but increasing tolerance to feedback requires complex stabilization mechanisms
Solution Approach 1:
The variable current channel structure creates an asymmetric current distribution along the cavity that inherently stabilizes laser operation against external optical feedback. By concentrating current injection in specific regions with appropriate photon density, the laser maintains stable single-mode operation and exhibits increased tolerance to feedback without requiring additional stabilization components or complex control mechanisms.
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 solution improves the conversion of electrical carriers to photons, reduces power consumption, and maintains high spectral purity, resulting in increased efficiency and tolerance to external optical feedback.
Implementation Method 1
laser efficiency may be determined in part by the appropriate matching of electrical charge injection to stimulated photon density within the optical cavity
Implementation Method 2
The variable current channel may modulate the current by varying the resistance per unit length along the length of the laser cavity
Implementation Method 3
In embodiments, a DFB laser may refer to a type of laser diode, quantum cascade laser or optical fiber laser where the active region of the device is periodically structured as a diffraction grating
Data Source
AI summary
Embodiments of the present disclosure may relate to a hybrid silicon distributed feed-back (DFB) laser, wherein light is to propagate through the DFB laser along a length of the DFB laser. The DFB laser may include a mesa with a current channel that extends from the first side of the mesa to the second side of the mesa. At a first location along the length of the DFB laser, the current channel may have a first width and/or the mesa may have a second width. At a second location along the length of the DFB laser, the current channel may have a third width and/or the mesa may have a fourth width as measured in a direction perpendicular to the length of the DFB laser. Other embodiments may be described and/or claimed.