MEMS-Tuned VCSEL Interferometer for Fast Wavelength Control
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Solution Overview
Problem
Existing methods for tuning the wavelength of laser diodes, such as changing the temperature, are time-consuming and can degrade the laser diode, offering a narrow tuning range and a shortened lifespan.
Innovation Solution
A self-mixing interferometry sensor is provided with a vertical cavity surface emitting laser (VCSEL) and a microelectromechanical system (MEMS) that allows for independent control of the laser cavity length by moving a partially reflective layer, enabling fast and wide-range wavelength tuning without temperature modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If temperature is changed to tune the laser diode wavelength, then wavelength tuning is achieved, but the tuning process becomes time-consuming and the laser diode lifespan is shortened
Solution Approach 1:
The patent replaces the thermal tuning mechanism with a mechanical tuning mechanism. A microelectromechanical system (MEMS) mirror is used to mechanically adjust the cavity length of the laser diode, enabling wavelength tuning without temperature changes. This substitution eliminates the time-consuming thermal tuning process while extending the laser diode lifespan by avoiding thermal stress.
2Adaptability or versatility
If temperature is changed to tune the laser diode wavelength, then wavelength tuning is achieved, but the laser diode is degraded and lifespan is shortened
Solution Approach 1:
The patent substitutes the thermal field with a mechanical field for wavelength tuning. The MEMS mirror mechanically adjusts the optical cavity length, allowing wavelength tuning without subjecting the laser diode to thermal cycling and thermal stress, thereby maintaining laser diode reliability and extending its operational lifespan.
3Adaptability or versatility
If traditional tuning methods are used, then wavelength adjustment is possible, but the tuning range is narrow and modulation speed is slow
Solution Approach 1:
The patent introduces dynamic tuning capability through the MEMS mirror, which can rapidly adjust the cavity length in real-time. This dynamic mechanical adjustment enables both wide wavelength tuning ranges and high modulation speeds, overcoming the limitations of static or slowly responding thermal tuning methods.
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 MEMS-based tuning achieves faster wavelength modulation speeds and larger tuning ranges than traditional methods, maintaining consistent power and junction temperatures, and providing linear wavelength tuning.
Implementation Method 1
a vertical cavity surface emitting laser (VCSEL) stacked with the photodetector and comprising a second set of semiconductor layers formed on the first set of semiconductor layers, and a microelectromechanical system (MEMS) stacked with the VCSEL on a side opposite from the photodetector
Implementation Method 2
the MEMS may be configured to change a length of a resonant cavity associated with the VCSEL, thereby changing a property of the emitted light
Implementation Method 3
a photodetector comprising a first set of semiconductor layers formed on a substrate
Implementation Method 4
The VCSEL may be further configured to receive reflections of the emitted light after the emitted light interacts with an object and undergo self-mixing interference after receiving the reflections of the emitted light
Data Source
AI summary
Self-mixing interferometry (SMI) sensors may include vertical cavity surface emitting lasers (VCSEL), photodetectors, and microelectromechanical systems (MEMS). The VCSEL, photodetectors, and MEMS may be vertically stacked. The MEMS may be moveable with respect to a VCSEL and may change a cavity length associated with the VCSEL. By changing the cavity length associated with the VCSEL, certain properties of emitted light may be changed, such as a wavelength value of the emitted light.