Optical Pulse Emitter Circuit for VCSEL Driving
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Solution Overview
Problem
Existing circuits fail to efficiently drive VCSELs or similar light emitting devices to generate optical pulses of high intensity and short duration, due to parasitic capacitance issues that slow the rising edge of the current, and lack of precise current control.
Innovation Solution
The optical pulse emitter employs a control circuit that manages switches and a capacitor to rapidly discharge the capacitor through a VCSEL, using phase signals to control the charging and discharging process, and includes a variable resistor and voltage regulating circuit to achieve precise current control and high current levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional circuit is used to drive a VCSEL, then the circuit structure is simple, but the rising edge of the current is slow due to parasitic capacitance issues
Solution Approach 1:
The circuit is segmented into distinct functional blocks: a capacitor charging circuit with first switch, a capacitor discharging circuit with second switch, and a voltage regulating circuit. This segmentation allows each block to be optimized independently, with the switching circuitry specifically designed to minimize parasitic capacitance and maximize current rising edge speed.
Solution Approach 2:
The capacitor is pre-charged to a predetermined voltage level before the optical pulse emission. This preliminary charging action ensures that when the second switch activates, the capacitor can immediately discharge through the VCSEL with maximum current rising edge speed, eliminating the need for slow in-rush current charging.
2Measurement precision
If a conventional circuit is used to drive a VCSEL, then the circuit structure is simple, but the current control precision is insufficient
Solution Approach 1:
A voltage regulating circuit with feedback mechanism is implemented to precisely control the voltage across the VCSEL during pulse emission. The feedback loop monitors the actual voltage and adjusts the discharge current accordingly, ensuring precise current control despite variations in VCSEL characteristics or operating conditions.
Solution Approach 2:
The circuit dynamically adjusts operating parameters including capacitor charging voltage, discharge resistance, and switching timing to optimize current control precision. By changing these parameters based on desired pulse characteristics, the system achieves precise control over the VCSEL drive current.
3Illumination intensity
If a conventional circuit is used to drive a VCSEL, then the circuit structure is simple, but the optical pulse intensity is insufficient
Solution Approach 1:
The capacitor is pre-charged to a high voltage level before pulse emission, storing sufficient energy to generate high-intensity optical pulses. This preliminary energy storage allows the VCSEL to be driven at maximum current levels for the duration of the pulse, achieving high optical intensity.
Solution Approach 2:
The circuit operates in periodic cycles of capacitor charging and discharging, with the second switch enabling high-current discharge phases separated by charging phases. This periodic action allows the VCSEL to be driven at high current levels repeatedly, generating high-intensity optical pulses at desired repetition rates.
4Duration of action of moving object
If a conventional circuit is used to drive a VCSEL, then the circuit structure is simple, but the pulse duration control is poor
Solution Approach 1:
The circuit employs dynamic switching control where the second switch is activated for precisely controlled durations to generate short-duration optical pulses. The switching timing and duration are dynamically adjusted based on desired pulse characteristics, enabling precise control over pulse width while maintaining simple overall circuit structure.
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 allows for the generation of high-intensity, short-duration optical pulses with precise current control, enabling efficient operation of VCSELs and other light emitting devices, such as in ranging devices.
Implementation Method 1
a capacitor having a first node coupled to the intermediate node
Implementation Method 2
A VCSEL (Vertical Cavity Surface-Emitting Laser) is a light emitting device capable of emitting light with an intensity that depends on a level of current driven through it
Data Source
AI summary
Disclosed herein is a method of optical pulse emission including three phases. During a first phase, a capacitor is charged from a supply voltage node. During a second phase, a voltage stored on the capacitor is boosted, and then the capacitor is at least partially discharged through a light emitting device. During a third phase, the capacitor is further discharged by bypassing the light emitting device. The third phase may begin prior to an end of the second phase.