Femtosecond Laser Waveguides for High-Power Visible Lasers
Solution Overview
Problem
Existing designs for nonlinear waveguides are limited in producing large-mode-area, single-mode, low-loss waveguides that can be produced in volume, which is crucial for high-power visible laser sources needed for next-generation cinema projectors.
Innovation Solution
The use of femtosecond laser writing techniques to fabricate wavelength-converting nonlinear waveguides on stoichiometric lithium tantalite substrates, with specific designs such as ridge, buried, and hybrid waveguides, allowing for efficient wavelength conversion and high power handling, and supporting single-mode operation with low propagation loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional fabrication methods are used for nonlinear waveguides, then manufacturing simplicity is maintained, but the ability to produce large-mode-area, single-mode, low-loss waveguides in volume is limited
Solution Approach 1:
The patent replaces conventional mechanical and chemical fabrication methods (such as lithography and etching) with direct laser writing using ultrashort laser pulses. This substitution enables precise control of waveguide properties through laser parameters while simplifying the manufacturing process into a single-step direct writing approach, resolving the contradiction between manufacturing precision and ease of manufacture
Solution Approach 2:
The patent utilizes changes in laser parameters (pulse duration, energy, repetition rate, wavelength) to directly control waveguide characteristics such as mode area, refractive index modification, and propagation loss. By adjusting these parameters, the system can produce large-mode-area, single-mode waveguides with low loss, achieving high manufacturing precision through parameter optimization rather than complex process control
2Loss of energy
If traditional waveguide designs are used, then device simplicity is maintained, but propagation loss increases and single-mode operation at large mode diameters cannot be achieved
Solution Approach 1:
The patent segments the waveguide structure into distinct functional regions: a core region with modified refractive index for light confinement, and a cladding region with different properties for mode control. This segmentation is achieved through controlled laser writing patterns that create different refractive index zones, enabling low-loss single-mode operation at large mode diameters while maintaining relatively simple overall device structure
Solution Approach 2:
The patent transitions from planar two-dimensional waveguide designs to three-dimensional structured waveguides with controlled depth profiles and cross-sectional geometries. By utilizing the third dimension (depth) for mode control, the system achieves low propagation loss and single-mode operation at large mode diameters without significantly increasing lateral device complexity
3Use of energy by moving object
If conventional laser diodes are used for visible light generation, then device simplicity is maintained, but power conversion efficiency and visible output quality are insufficient
Solution Approach 1:
The patent employs nonlinear optical phase transitions, specifically second-harmonic generation, to convert infrared laser light to visible wavelengths. This phase transition process occurs within the periodically poled lithium niobate waveguide, achieving high power conversion efficiency while integrating the wavelength conversion function directly into the waveguide structure, thereby minimizing additional system complexity
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 described waveguide designs enable the production of high-power visible laser sources with efficient wavelength conversion and low propagation loss, supporting single-mode operation and large mode diameters, thereby addressing the limitations of existing technologies.
Implementation Method 1
a plurality of laser-written damage tracks in the nonlinear crystal substrate, wherein the damage tracks have a crystalline structure different from an undamaged crystalline structure of the nonlinear crystal substrate
Implementation Method 2
wavelength-converting nonlinear waveguide
Data Source
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Figure 3(a)~3(c)
AI summary
Novel methods and systems for waveguide fabrication and design are disclosed. Designs are described for fabricating ridge, buried and hybrid waveguides by a femtosecond pulsed laser. A laser system may combine a diode bar, a wavelength combiner and a waveguide. The waveguide may convert the electromagnetic radiation of an infrared laser into that the visible-wavelength range.