Thin-Film Laser Resonator Planarization for Uniform Current Injection
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Solution Overview
Problem
Existing solid-state thin-film lasers face challenges with non-uniform electrode deposition due to high-aspect-ratio features, leading to electrical leakage, optical losses, and unstable lasing modes due to uneven current injection and gain distribution.
Innovation Solution
The development of an electrically-operable laser device with an in-plane resonator comprising two solid materials of low electrical conductivity, differing in refractive indices, and a planar surface roughness below 5 nm, allowing for uniform layer deposition and improved optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a 70-100 nm ITO electrode is deposited on high-aspect-ratio DFB grating features, then the resonator structure is formed, but non-uniform layer thickness results causing electrical leakage and optical losses
Solution Approach 1:
The patent applies planarization processes (chemical mechanical polishing or etch-back) to the DFB grating structure before electrode deposition. This preliminary action removes the high-aspect-ratio features that cause deposition non-uniformity, creating a flat surface that enables conformal electrode layer formation with consistent thickness, thereby preventing electrical leakage and optical losses
2Manufacturing precision
If thickness-modulated layers are used in the resonator structure, then the DFB grating function is achieved, but uneven current injection occurs leading to unpredictable gain distribution
Solution Approach 1:
The patent planarizes the resonator structure before depositing subsequent functional layers including electrodes and gain media. This preliminary planarization action ensures that thickness modulation is confined to the resonator layer only, while overlying layers maintain uniform thickness, resulting in homogeneous current injection and stable single-mode lasing operation
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 enables better vertical current injection, reduced optical scattering, and stable lasing modes with improved reliability and efficiency in light emission.
Implementation Method 1
The in-plane resonator comprises at least two solid materials, each having an electrical conductivity below 3 S/m at 20° C., wherein two or more of the at least two solid materials differ in their refractive indices
Data Source
AI summary
An electrically-operable laser device for emitting light at least at a wavelength includes a substrate; at least a first in-plane resonator; a first electrode; a lasing gain medium; and a second electrode. Each resonator includes at least two solid materials having an electrical conductivity below 3 S/m, wherein two or more of the solid materials differ in their refractive indices. The top surface of the first in-plane resonator is planar and has a root mean square roughness below 5 nm. The first resonator is either a) situated above the substrate, or b) comprises a material of the substrate as a first of the at least two solid materials. Any further in-plane resonators, if present, are situated above the substrate.