Semiconductor Laser Pulse Circuit Layout for Back-EMF Isolation
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Solution Overview
Problem
The counter electromotive force due to inductance affects the control voltage of switching elements in semiconductor laser devices, particularly when switching elements are used in pulsed laser systems, leading to inefficiencies and potential damage.
Innovation Solution
A semiconductor laser device is designed with a capacitor connected in parallel to the semiconductor laser element and switching element, along with separate paths for current flow through drive connection members, reducing the impact of inductance on the control voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the pulse width is reduced to a few dozen nanoseconds or less, then the laser beam emission speed and responsiveness are improved, but the time rate of change in current increases, causing increased counter electromotive force due to inductance
Solution Approach 1:
The patent extracts the harmful inductive effect from the control circuit by introducing a separate drive circuit for the second drive electrode. This independent drive path eliminates the counter electromotive force generated in the control electrode circuit, allowing fast pulse widths without affecting the control voltage stability.
Solution Approach 2:
The patent segments the drive circuit into two independent paths: one for the control electrode and another for the second drive electrode. This segmentation isolates the high-current switching path from the control voltage path, preventing the counter electromotive force from affecting the control electrode while enabling rapid pulse operation.
2Stability of the object's composition
If the counter electromotive force is reduced, then the control voltage stability is improved, but additional circuit components and complexity are introduced
Solution Approach 1:
The second drive electrode is given dual functionality: it serves both as a current path for the switching element and as a control terminal. This multi-functionality allows the circuit to maintain control voltage stability without adding completely separate control circuitry, thereby reducing overall system complexity while achieving the desired stability.
3Reliability
If separate current paths are used, then the effect of inductance on control voltage is reduced, but the device structure becomes more complex
Solution Approach 1:
The patent merges the second drive electrode with the control electrode structure, allowing it to serve both as part of the current-carrying path and as a control terminal. This merging reduces structural complexity compared to having completely separate paths, while still achieving the goal of isolating the control voltage from inductive effects through the separate drive circuit architecture.
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 configuration minimizes the effect of counter electromotive force on the control voltage, enhancing the stability and efficiency of the semiconductor laser device.
Implementation Method 1
The capacitor is configured to be connected in parallel to the semiconductor laser element and the switching element
Implementation Method 2
The first drive connection member connects the first drive conductor and the second drive electrode. The second drive connection member connects the second drive conductor and the second drive electrode
Data Source
AI summary
This semiconductor laser device comprises: a semiconductor laser element; a switching element connected in series to the semiconductor laser element, the switching element having a gate electrode, a drain electrode, and a source electrode; capacitors connected in parallel to the semiconductor laser element and the switching element; first drive electroconductive parts to which first terminals of the capacitors are connected; a second drive electroconductive part positioned apart from the first drive electroconductive parts; first drive connection members that connect the first drive electroconductive parts and the source electrode; and a second drive connection member that connects the second drive electroconductive part and the source electrode.