Free-Space SLED Module for Broad-Bandwidth Beam Combining
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Solution Overview
Problem
Current superluminescent light emitting diodes (SLEDs) are limited by narrow emission bandwidths, making them unsuitable for applications requiring broader bandwidths, such as display and optical coherence tomography, and implementing polarization-maintaining fiber couplers is technically challenging.
Innovation Solution
A module design comprising multiple SLED sources with a beam combiner in a free-space enclosure, allowing for the combination of SLED beams into a continuous spectrum covering multiple wavelength ranges, with optional edge filters and beam-shaping components to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple SLEDs are combined using fiber couplers, then the emission bandwidth is increased, but the device complexity and difficulty of polarization control increase
Solution Approach 1:
The patent transitions from fiber-based coupling (one-dimensional waveguide confinement) to free-space optical coupling (three-dimensional spatial freedom). By using free-space beam combination with mirrors and beam combiners, the system achieves broader bandwidth combination without the polarization-maintaining complexities of fiber couplers, resolving the contradiction between bandwidth expansion and device complexity
Solution Approach 2:
The patent extracts the polarization-maintaining requirement from the coupling mechanism by removing the fiber coupler component entirely. By using free-space optics, the system separates the functions of beam combination and polarization control, allowing independent optimization and reducing overall device complexity while maintaining broad emission bandwidth
2Device complexity
If a single SLED is used, then the device complexity is reduced, but the emission bandwidth is insufficient for display and OCT applications
Solution Approach 1:
The patent merges multiple SLED sources with different wavelength ranges (red, green, blue SLEDs) into a single integrated module using free-space beam combination. This allows the system to achieve the broad emission bandwidth required for RGB display and OCT applications while maintaining a compact, integrated design that does not significantly increase device complexity
Solution Approach 2:
The patent creates a universal SLED module that can serve multiple applications (display and OCT) by combining multiple wavelength ranges in a single device. The free-space beam combination architecture allows the same module to provide both the broad bandwidth needed for OCT and the RGB coverage needed for display 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 module achieves a broader emission bandwidth suitable for display and optical coherence tomography systems, with improved polarization control and reduced technical challenges in combining SLED outputs.
Implementation Method 1
The outputs from the upper two SLED modules 5r, 5b are carried by respective optical fibers 20, 22, which lead to a fiber coupler 26 where the two outputs 5r, 5g are combined into a single output fiber 28
Implementation Method 2
The source modules 5r/g/b each include an optical fiber pigtail 16 for coupling the light from the SLED source 12 into the end of an optical fiber via a coupling lens 14
Data Source
AI summary
A module accommodates multiple superluminescent light emitting diodes, SLEDs, 12r, 12g and 12b. The SLEDs are arranged in an enclosure and output respective light beams to propagate into free space within the enclosure. The individual light beams from the SLED sources are combined into a single beam path within the enclosure using beam combiners 40r-g, 40rg-b. Each beam combiner is realized as a planar optical element, the back side of which is arranged to receive a SLED beam and route it through the optical element to the front side where it is combined with another SLED beam that is incident on and reflected by the front side. The free-space propagating combined beam is output from the module via an optical fiber 42 (or through a window).