Correction Circuit for Surface-Emitting Semiconductor Laser Waveform
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Surface-emitting semiconductor lasers experience dullness in optical output waveform due to wavelength detuning, which is exacerbated by high temperatures, making high-output operation challenging, especially in red or infrared lasers.
Innovation Solution
A correction circuit that superposes a second current pulse on a first current pulse to correct the waveform, with the second pulse's crest value attenuated over time, increasing the initial crest value based on the magnitude of the first pulse and reducing the increase as ambient temperature rises, to achieve a more rectangular optical output waveform.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the wavelength detuning is increased to reduce threshold current in red or infrared surface-emitting semiconductor lasers, then the threshold current becomes smaller, but the optical output waveform becomes dulled
Solution Approach 1:
The correction circuit pre-processes the drive current pulse waveform before it reaches the laser, by superimposing a compensation pulse that anticipates and counteracts the waveform dulling effect. This preliminary action occurs in the electrical domain before optical output is generated, preventing the waveform degradation from manifesting in the final optical output.
Solution Approach 2:
The invention changes the temporal parameters of the drive current pulse by dynamically adjusting its waveform characteristics. The correction circuit modifies the current pulse shape based on detected optical output waveform characteristics, transforming the parameter set of the drive signal to compensate for the wavelength detuning-induced dulling effect.
2Power
If the device temperature is increased to achieve minimum threshold current when wavelength detuning is large, then the threshold current is minimized, but the waveform dullness is exacerbated
Solution Approach 1:
The correction circuit acts as an intermediary between the drive signal source and the laser, introducing a compensating signal that mediates the adverse thermal effects. This intermediary component processes the drive current to counteract temperature-induced waveform degradation, allowing the system to operate at optimal temperature without suffering from exacerbated waveform dullness.
3Device complexity
If a simple current pulse is applied to drive the laser, then the drive circuit is simple, but the optical output waveform becomes dulled due to wavelength detuning
Solution Approach 1:
The correction circuit employs feedback mechanisms to detect the actual optical output waveform characteristics and uses this information to adjust the drive current pulse waveform in real-time. This feedback loop enables the system to maintain precise waveform control without requiring overly complex preliminary circuit design, as the correction adapts dynamically to actual operating conditions.
Data Source
AI summary
A correction circuit includes a correction section configured to superpose a second current pulse on a first current pulse, and thereby correcting a waveform of the first current pulse, the first current pulse being output from a current source configured to drive a surface-emitting semiconductor laser in a pulsed manner, the correction section being configured to allow the second pulse to have a waveform obtained through attenuating a crest value of the second current pulse with time, increasing an initial crest value of the second current pulse by an amount that is larger as magnitude of the first current pulse is larger, and allowing the amount by which the initial crest value is increased to be smaller as ambient temperature of the semiconductor laser is higher, and being configured to output the second pulse having the waveform.