Fiber-Coupled White Light Source Using Laser-Excited Phosphor
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Solution Overview
Problem
Conventional light sources, such as incandescent bulbs and LEDs, face issues like high energy dissipation, thermal instability, broad spectral emission, and lack of directionality, which limit their efficiency and application in specific lighting needs.
Innovation Solution
A compact, high-brightness white light source is created by integrating gallium and nitrogen-based laser diodes with phosphor materials, enabling efficient energy conversion and directional light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional light bulbs use tungsten filament, then light emission is achieved, but more than 90% of energy is dissipated as thermal energy
Solution Approach 1:
The patent replaces the thermal radiation mechanism of incandescent bulbs with a cold cathode field emission mechanism. Electrons are emitted from a cathode via quantum tunneling under strong electric fields, eliminating the need for thermal heating of a filament. This substitution of the light generation mechanism from thermal to electrical field-based process resolves the energy efficiency contradiction by avoiding the 90% thermal energy loss inherent in incandescent operation.
2Illumination intensity
If conventional light bulbs operate at high temperature, then light emission is maintained, but thermal expansion and contraction causes routine failure
Solution Approach 1:
The patent eliminates the thermal cycling mechanism that causes filament failure by replacing it with a cold cathode field emission system. The cathode operates at or near room temperature, with light generation occurring through quantum tunneling of electrons under applied electric fields rather than thermal radiation. This removes the thermal expansion and contraction cycles that routinely cause conventional filament bulb failure, dramatically improving reliability.
3Adaptability or versatility
If conventional light bulbs emit light in all directions, then omnidirectional illumination is achieved, but directionality and focus are lost
Solution Approach 1:
The patent employs segmented or patterned cathode structures that can be configured to emit electrons in specific directions. By dividing the cathode into discrete emission zones or using shaped cathodes, the system achieves directional control over the light output. This segmentation approach allows the bulb to provide focused illumination in desired directions while maintaining the ability to illuminate multiple zones, resolving the contradiction between omnidirectional coverage and directional focus.
4Illumination intensity
If conventional light bulbs emit broad spectrum light, then full spectrum coverage is achieved, but much of the light is not perceived by the human eye
Solution Approach 1:
The patent uses selective cathode materials and surface treatments that are engineered to emit electrons with specific energy distributions corresponding to visible wavelengths. By tailoring the local properties of the cathode surface (such as work function, surface morphology, and material composition), the system produces light primarily in the visible spectrum where human eyes are sensitive. This local quality optimization eliminates waste energy in ultraviolet and infrared regions while maintaining full visible spectrum coverage for effective illumination.
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
This solution provides a cost-effective, highly efficient, and directional white light source with improved color rendering and longer lifespan, suitable for various applications including lighting, displays, and automotive headlamps.
Implementation Method 1
a laser device including a gallium and nitrogen containing material and configured as an excitation source with an output facet configured to output a laser emission with a first wavelength
Implementation Method 2
a laser device including a gallium and nitrogen containing material and configured as an excitation source
Implementation Method 3
the phosphor member converts the laser emission with the first wavelength to a phosphor emission with a second wavelength that is longer than the first wavelength
Implementation Method 4
the phosphor emission is reflected from the spot to the same side of the excitation surface to mix at least partially with laser emission to produce a white light emission
Implementation Method 5
a fiber coupled to the phosphor member to capture the white light emission with at least 20% efficiency to deliver or distribute the white light emission
Data Source
AI summary
A laser-based fiber-coupled white light system is provided. The system includes a laser device comprising a gallium and nitrogen containing emitting region having an output facet configured to output a laser emission with a first wavelength ranging from 385 nm to 495 nm. The system further includes a phosphor member to receive the laser emission in a range of angles of incidence to a spot on a primary surface with a size greater than 5 μm. The phosphor member converts the laser emission with the first wavelength to a phosphor emission with a second wavelength in either reflective or transmissive mode and mixed at least partially with laser emission to produce a white light emission. Additionally, the system includes a fiber coupled to the phosphor member to capture the white light emission to deliver the white light emission to a remote lighthead or distribute the white light emission directly.