PCSEL Sensing Structure for Precise SMI and FMCW Ranging
Solution Overview
Problem
Existing laser diode technologies, such as photonic crystal surface-emitting laser diodes (PCSELs), face challenges in efficiently utilizing self-mixing interference (SMI) and frequency modulated continuous wave (FMCW) sensing for accurate object detection and distance measurement in various environmental conditions.
Innovation Solution
The development of electronic devices and systems that incorporate PCSELs with associated photodetectors, utilizing SMI and FMCW sensing techniques. These systems include a photonic crystal light emitting laser diode with a photonic crystal layer, active region, and semiconductor cladding layers, along with a distributed Bragg reflector (DBR) and a photodetector configured to receive secondary light emissions and produce measurable electrical parameters related to self-mixing or frequency modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PCSELs are configured for SMI or FMCW sensing, then measurement precision is improved, but device complexity increases due to integration of photonic crystal layers, DBR structures, and photodetectors
Solution Approach 1:
The patent combines multiple functional components (photonic crystal layer, active region, DBR, and photodetector) into an integrated PCSEL device structure. The photonic crystal layer is formed within the laser diode cavity, the DBR is integrated as a reflection layer, and the photodetector is positioned to receive secondary emissions, creating a unified sensing system that enables SMI and FMCW measurements.
Solution Approach 2:
The PCSEL device is designed to perform multiple functions: it generates primary light emissions for illumination, produces secondary light emissions for detection, and enables both SMI and FMCW sensing modes. This multi-functionality allows a single device structure to serve as both a light source and a sensing system.
2Reliability
If photonic crystal layers and DBR structures are integrated into PCSELs, then sensing reliability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The device is segmented into distinct functional layers (photonic crystal layer, active region, DBR, photodetector) that can be independently designed and optimized. Each layer performs a specific function, allowing for modular manufacturing and testing while maintaining overall system reliability.
Solution Approach 2:
The photonic crystal layer parameters (hole size, spacing, depth) and DBR parameters (layer thickness, refractive index) are carefully controlled and optimized to achieve the desired sensing performance. By adjusting these parameters, the device can be tuned for specific wavelength ranges and sensing applications.
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 proposed solution enables accurate and efficient object detection and distance measurement by effectively utilizing SMI and FMCW sensing techniques, improving the precision and reliability of laser diode-based sensor systems.
Implementation Method 1
The photonic crystal light emitting laser diode is configured to make a primary light emission through the substrate toward an object
Implementation Method 2
the photodetector configured to receive a secondary light emission emitted from the photonic crystal surface-emitting laser diode through the second semiconductor cladding layer and the DBR, with the photodetector configured to produce a measurable electrical parameter related to self-mixing of light within the photonic crystal surface-emitting laser diode
Data Source
AI summary
Disclosed herein are self-mixing interference (SMI) sensors, frequency modulated continuous wave (FMCW) sensors, and electronic devices that include SMI and FMCW sensors. Both types of sensors include a photonic crystal surface-emitting laser diode. The SMI sensors include a photonic crystal surface-emitting laser diode configured to undergo SMI between a primary emitted light from the photonic crystal surface-emitting laser diode and reflections thereof from an object. The SMI sensor includes a photodetector configured to receive a secondary light emission from the photonic crystal surface-emitting laser diode and detect a parameter related to the SMI, from which distance or motion to the object may be inferred. The FMCW sensors include a photonic crystal surface-emitting laser diode configured to emit a primary light emission toward the object and a secondary light emission toward a light beam combiner. The light beam combiner also receives reflections from the object and detects distances and/or motion of the object based on the frequency modulations of the two light beams.