Series Laser Current Shifting for Uneven Lasing Thresholds
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Solution Overview
Problem
In series configurations of laser elements, each laser element receives the same current, despite having different lasing current thresholds, leading to uneven light outputs and potential damage from overcurrent.
Innovation Solution
A laser element module is designed with each laser element coupled in series with a capacitor and powered by a bias current source and a modulation current source. The bias current source ensures each laser element receives at least its lasing current threshold, while the modulation current source provides an alternating current to enhance light output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If laser elements are connected in series to share a single current source, then device complexity is reduced, but each laser element receives the same current which does not account for different lasing current thresholds, resulting in uneven light output and potential overcurrent damage
Solution Approach 1:
The patent divides the single current source into multiple independent current sources, with each laser element having its own dedicated current source. This segmentation allows each laser element to receive the specific current it requires based on its individual lasing current threshold, preventing overcurrent damage while maintaining reliable operation.
2Ease of operation
If a single current source is used for all laser elements, then ease of operation is improved, but the inability to provide different currents to each laser element results in some elements operating inefficiently or damagingly
Solution Approach 1:
The patent segments the current control system into individual current sources for each laser element. This allows each element to operate at its optimal current level, maximizing energy efficiency and preventing energy loss from overcurrent or undercurrent conditions, while still maintaining simple operation through independent control.
3Power
If drive current is increased to increase optical output power, then power output is improved, but this causes catastrophic optical damage through short circuits and crystal defects
Solution Approach 1:
The patent changes the current parameter for each laser element individually based on its specific lasing current threshold. By adjusting the current to the precise level needed for each element rather than using a high overcurrent, the system achieves optimal optical output power while preventing catastrophic optical damage from excessive current.
Data Source
AI summary
The invention relates to a laser element module comprising a first laser module comprising a first laser element and a first capacitor, wherein the first laser element is coupled in series with the first capacitor; a second laser module comprising a second laser element and a second capacitor, wherein the second laser element is coupled in series with the second capacitor, wherein the first laser module is coupled in series with the second laser module; a bias current source adapted to provide a first bias current to the first laser element and a second bias current to the second laser element; a modulation current source adapted to provide an alternating current to the first capacitor, wherein the bias current source and the modulation current source, when active, are arranged to provide a total current to the first laser element and the second laser element which is always larger than a lasing current threshold of the first laser element and a lasing current threshold of the second laser element.