Tunable Laser Power Compensation for Detector Linearity
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Solution Overview
Problem
Existing semiconductor devices used in tunable lasers are not satisfactory in maintaining constant optical power across a tunable range, leading to variations in sample data acquisition due to non-linear detector responses and varying background absorptions.
Innovation Solution
A system comprising a tunable laser assembly with a gain medium, a detector assembly, and a laser controller that dynamically adjusts the laser drive to maintain substantially constant optical power at the detector assembly, compensating for background absorptions and thermal loads, ensuring optimal linear response and minimizing noise across the tunable range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the laser wavelength is tuned quickly across the tunable range in a single sweep, then the data acquisition time is reduced and sample variations are minimized, but the optical power at the detector becomes non-constant due to varying background absorptions and detector response
Solution Approach 1:
The patent applies dynamics by making the laser drive current dynamically adjustable during the tuning sweep. The controller modifies the drive current in real-time as the laser wavelength changes, allowing the optical power to be actively compensated and maintained at a constant level throughout the sweep, thus resolving the contradiction between fast tuning and power stability
Solution Approach 2:
The patent changes the electrical parameter (laser drive current) as a function of wavelength to compensate for optical parameter variations. By adjusting the drive current dynamically during the sweep, the system maintains constant optical power at the detector despite changes in background absorption and detector response across the tunable range
2Reliability
If the laser drive is increased to compensate for background absorptions, then the optical power at the detector is maintained, but the thermal load on the gain medium increases causing wavelength instability
Solution Approach 1:
The patent carefully modulates the laser drive current parameter to achieve the minimum necessary increase to compensate for background absorptions while avoiding excessive thermal loading. This controlled parameter adjustment maintains detector power while limiting temperature-induced wavelength drift
Solution Approach 2:
The system uses feedback from the detector to monitor optical power levels and adjusts the laser drive accordingly. This closed-loop control ensures that the drive current is increased only to the extent necessary to maintain constant power at the detector, preventing excessive thermal load on the gain medium
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 system ensures consistent optical power and optimal linear response at the detector assembly, minimizing noise and maintaining sensitivity across the tunable range, even in the presence of varying background absorptions, thereby improving data quality and stability.
Implementation Method 1
a tunable laser assembly that is tunable over a tunable range, the tunable laser assembly including a gain medium that generates an illumination beam
Implementation Method 2
a detector assembly having a linear response range with an upper bound and a lower bound
Implementation Method 3
the optical power directed at the sample is adjusted to compensate for background absorptions near the sample
Data Source
AI summary
An assembly (14) for analyzing a sample (15) includes a detector assembly (18); a tunable laser assembly (10); and (iii) a laser controller (10F). The detector assembly (18) has a linear response range (232) with an upper bound (232A) and a lower bound (232B). The tunable laser assembly (10) is tunable over a tunable range, and includes a gain medium (10B) that generates an illumination beam (12) that is directed at the detector assembly (18). The laser controller (10F) dynamically adjusts a laser drive to the gain medium (10B) so that the illumination beam (12) has a substantially constant optical power at the detector assembly (18) while the tunable laser assembly (10) is tuned over at least a portion of the tunable range.