Tunable Wavelength Gain Chip Array for Sensing
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Solution Overview
Problem
Existing surface-emitting semiconductor light sources, such as RC-LEDs and VCSELs, face limitations in reliability, temperature sensitivity, and random interferences due to their coherence length, making them unsuitable for applications requiring high brightness and fast response without lasing.
Innovation Solution
A surface-emitting superluminescent diode array with a common substrate and plural gain chips, each configured to generate a light beam, featuring optical couplers and feedback control mechanisms for tunable wavelength, allowing for combined light output without lasing, enhancing efficiency and directionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If laser diodes are used to provide high brightness and fast response, then the light coherence is high, but random interferences occur due to long coherence length
Solution Approach 1:
The patent changes the coherence length parameter by using a distributed feedback (DFB) laser design with a specific grating structure that provides wavelength selection and reduces coherence length. The grating period and depth are optimized to achieve short coherence length while maintaining high brightness through stimulated emission.
Solution Approach 2:
The patent introduces an optical isolator as an intermediary component in the optical path to prevent back-reflected light from entering the laser cavity. This isolator acts as a mediator that blocks harmful reflections while allowing the forward propagating laser beam to pass through, thereby eliminating random interferences.
2Ease of manufacture
If surface-emitting structure is used for easy integration and fiber coupling, then the mounting is simpler, but the active region thickness limits light amplification
Solution Approach 1:
The patent transitions from lateral light extraction to vertical surface-emitting geometry, changing the dimension of light extraction. This vertical configuration allows direct fiber coupling from the top surface while maintaining sufficient optical path length through the gain medium by optimizing the vertical cavity design and active region thickness.
Solution Approach 2:
The patent implements a nested structure where the active region is positioned within a resonant cavity formed by distributed Bragg reflectors (DBRs). The DBRs are nested around the active region, creating a confined optical path that enhances light amplification through multiple passes while maintaining a compact surface-emitting form factor suitable for fiber integration.
3Power
If distributed Bragg reflectors are used to reflect light multiple times for amplification, then the light extraction is improved, but the device complexity increases
Solution Approach 1:
The patent segments the optical cavity into distinct functional regions: a high-reflectivity DBR at the bottom for light amplification and a partially transparent top DBR for light extraction. This segmentation allows each reflector to be optimized for its specific function, achieving high amplification while controlling the complexity through modular design.
Solution Approach 2:
The patent applies different reflectivity qualities to different parts of the cavity: the bottom DBR has high reflectivity (R>99%) for maximum amplification, while the top DBR has lower reflectivity (R<90%) to allow light extraction. This local differentiation of optical properties optimizes both amplification and extraction without requiring complex structures throughout the entire device.
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 solution provides a reliable, high-brightness, and fast-response light source with reduced coherence, suitable for applications like optical communication and sensing, offering improved performance over traditional LEDs and lasers.
Implementation Method 1
The principle on which SLDs is based is amplified spontaneous emission (ASE), in which a gain medium is used to amplify the light generated from spontaneous emission
Implementation Method 2
an array wide optical coupler connected to another end of the plural optical fibers, and a single optical fiber connected to the array wide optical coupler and configured to output the combined light beams
Data Source
AI summary
An array of surface-emitting gain chips includes a common substrate, plural gain chips formed on the common substrate, each configured to generate a light beam, plural optical couplers, each located on a top surface of a corresponding gain chip of the plural gain chips, plural optical fibers, each connected with one end to a corresponding optical coupler of the plurality of optical couplers, an array wide optical coupler connected to another end of the plural optical fibers, and a single optical fiber connected to the array wide optical coupler and configured to output the combined light beams.