Light Emitting Device Using Relaxation Oscillation for Short Pulse Width
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Solution Overview
Problem
Existing technologies face challenges in generating short pulse-width laser light due to difficulties in creating driving currents with time lengths of several tens to several hundreds of picoseconds, particularly in outdoor devices where high-frequency microwave techniques are not feasible due to circuit scale, production cost, and power consumption issues.
Innovation Solution
A light emitting device comprising a light source, a capacitive reactance circuit, a resistance circuit, and a switching element, where the capacitive reactance circuit exhibits low impedance to generate inrush current, and the resistance circuit discharges electrical charge after a predetermined time, connected in series with the light source to produce relaxation oscillation and suppress subsequent oscillations, allowing for the emission of a single pulse of light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If high frequency technique in microwave band is used to obtain pulse-like driving current with time length of several tens to several hundreds of picoseconds, then the pulse width of light emission can be shortened, but the circuit scale increases, production cost increases, adjustment becomes complicated, and electric power consumption increases
Solution Approach 1:
The patent changes the approach from using high-frequency microwave signals to utilizing the natural relaxation oscillation characteristics of the laser diode itself. By carefully controlling the driving current waveform and timing, the system exploits the inherent dynamic response of the LD to generate short pulses without requiring complex high-frequency circuitry. This parameter change transforms the problem from one of signal generation to one of temporal control of a simpler signal.
Solution Approach 2:
The invention makes the laser diode serve itself by utilizing its own relaxation oscillation phenomenon to generate the desired short pulses. Instead of requiring an external high-frequency signal source to drive the LD, the system allows the LD's natural response to the applied current to produce the pulse output. This self-service approach eliminates the need for complex external microwave generation equipment.
2Duration of action of moving object
If high frequency technique in microwave band is used to obtain pulse-like driving current, then the pulse width of light emission can be shortened, but power consumption increases
Solution Approach 1:
The patent changes the energy approach from sustained high-frequency microwave power delivery to a transient current pulse that exploits the laser diode's natural relaxation oscillation. This parameter change in the driving methodology reduces the overall energy consumption while achieving the same short pulse width effect, as the system uses the LD's inherent dynamic response rather than forcing it with continuous high-frequency energy.
3Device complexity
If simple circuit is used to generate driving current, then circuit complexity is reduced, but it becomes difficult to obtain pulse-like driving current with time length of several tens to several hundreds of picoseconds
Solution Approach 1:
The invention makes the laser diode serve itself by utilizing its own relaxation oscillation phenomenon to generate the desired short pulses. Instead of requiring an external high-frequency signal source to drive the LD, the system allows the LD's natural response to the applied current to produce the pulse output. This self-service approach eliminates the need for complex external microwave generation equipment.
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 device achieves emission of light with a short pulse width using a simple structure, reducing the need for complex high-frequency circuits and minimizing power consumption, while maintaining precision in applications like distance measurement.
Implementation Method 1
The capacitive reactance circuit exhibits low impedance immediately after the electric current is applied and is charged by the electric charge
Implementation Method 2
The resistance circuit discharges the electrical charge charged in the capacitive reactance circuit after a predetermined time passes after the electric current is applied
Implementation Method 3
The light source generates relaxation oscillation immediately after electric current is supplied thereto for driving light emission
Data Source
AI summary
Light with a short pulse width is emitted using a simple structure. A light source 101, a differentiation circuit 102, and a switch 103 are connected in series. When the switch 103 is switched on, inrush current flows in a capacitor 102b forming the differentiation circuit 102, and accordingly the light source 101 is supplied with electric current and thereby emits light. When the capacitor 102b is charged, electric current flows in a resistor 102a, and voltage drops at the resistor 102a. Then, the voltage applied to the light source 101 is decreased, whereby the light source 101 stops emitting light. By using the inrush current at the capacitor 102b, light with a short pulse width can be generated.