Planar SLED Module for Broadband Output and Polarization Control
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Solution Overview
Problem
Current SLEDs have limited emission bandwidths, making them unsuitable for applications requiring broader bandwidths, such as display and optical coherence tomography, and maintaining polarization in combined outputs is technically challenging.
Innovation Solution
A module design incorporating multiple SLED sources with beam combiners and edge filters to combine SLED beams into a continuous spectrum, using planar optical elements and lens components to manage beam paths and polarization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If multiple SLEDs are combined using fiber couplers, then the emission bandwidth is increased, but polarization control becomes difficult and losses increase
Solution Approach 1:
The patent segments the broadband emission requirement into multiple narrowband SLED sources operating at different center wavelengths. Each SLED emits in a limited bandwidth (50-70nm in NIR, 10-30nm in visible), but by combining multiple segmented sources with different center wavelengths, the system achieves a total bandwidth exceeding 200nm that would be impossible for a single SLED to provide.
Solution Approach 2:
The patent introduces planar optical elements (beam combiners, mirrors, lenses) as intermediaries to combine the beams from multiple SLEDs. These planar elements replace the problematic fiber couplers and maintain polarization control by providing stable, predictable optical paths. The planar combiner architecture serves as an intermediary that preserves polarization while achieving broadband combination.
2Device complexity
If a single SLED is used, then polarization control is simplified, but the emission bandwidth is insufficient for display and OCT applications
Solution Approach 1:
The patent merges multiple SLED sources with different center wavelengths into a single combined beam output. By combining sources at different wavelengths (e.g., blue, green, red in visible; or multiple NIR wavelengths) through planar optical elements, the system achieves a merged broadband output that covers the full spectrum needed for display (RGB) or OCT applications, while maintaining polarization control through the planar architecture.
3Extent of automation
If fiber couplers are used to combine SLED outputs, then bandwidth extension is achieved, but polarization-maintaining becomes technically challenging
Solution Approach 1:
The patent substitutes the mechanical fiber coupling system with a planar optical system using beam combiners, mirrors, and lenses. This replacement eliminates the polarization-mixing problems inherent in fiber couplers while achieving the same bandwidth extension goal. The planar optical path provides stable, predictable polarization maintenance that is not achievable with flexible fiber connections.
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 combined emission spectrum and improved polarization control, suitable for applications like optical coherence tomography and display systems.
Implementation Method 1
a beam combiner arranged in the enclosure to receive the first SLED beam and the second SLED beam, and to combine them into a combined SLED beam
Implementation Method 2
edge filters to combine SLED beams into a continuous spectrum
Implementation Method 3
lens components to manage beam paths
Implementation Method 4
using planar optical elements and lens components to manage beam paths and polarization
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).