Photonic Crystal Laser Current Confinement for Surface Emission
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Solution Overview
Problem
Electrically pumped photonic crystal surface emitting lasers face challenges in efficiently distributing electric currents due to the lattice structure of photonic crystals, affecting light transmission and carrier distribution.
Innovation Solution
The design includes a substrate with a photonic crystal structure formed by multiple holes in an epitaxy structure, an insulating layer with apertures, and a light-transmissive conducting layer to facilitate electrical current confinement and distribution, enabling efficient surface emission of laser beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a photonic crystal lattice structure is used to confine electromagnetic waves and form a cavity, then laser beam quality is improved, but electric current input becomes difficult and carrier distribution is affected
Solution Approach 1:
The patent introduces an insulating layer with apertures as an intermediary between the photonic crystal lattice and the electrical contact structure. This mediator allows electrical current to be input through specific openings while the surrounding insulating material maintains the photonic crystal's electromagnetic confinement properties, thus resolving the contradiction between beam quality and ease of current input
Solution Approach 2:
The patent segments the contact layer into multiple regions with different functionalities: some areas are covered by insulating material to maintain photonic crystal properties, while other areas have apertures for electrical contact. This segmentation allows simultaneous achievement of high beam quality through lattice confinement and easy current input through designated contact regions
2Power
If the photonic crystal lattice structure is used to confine electromagnetic waves, then laser threshold is reduced, but routes for light transmission and carrier distribution become complex
Solution Approach 1:
The patent resolves the complexity issue by introducing a vertical dimension to the problem. The insulating layer with apertures is positioned above the photonic crystal lattice in the vertical direction, allowing light transmission and carrier distribution routes to be clearly separated in different spatial dimensions. This dimensional separation simplifies the overall route design while maintaining the low threshold benefits of photonic crystal confinement
3Power
If electric currents are distributed through the photonic crystal structure, then laser power output is improved, but losses increase due to the lattice structure
Solution Approach 1:
The patent extracts the electrical current input function from the photonic crystal lattice itself by introducing separate apertures in the insulating layer. This extraction allows current to be supplied through optimized contact regions without forcing it through the lossy lattice structure, thereby reducing energy losses while maintaining high power output capability
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 configuration enhances the efficiency of electrically pumped photonic crystal surface emitting lasers by reducing losses and improving the confinement of electrical currents, leading to effective surface emission with narrow divergence angles and high power output.
Implementation Method 1
Photonic crystals are periodic metamaterials that can be fabricated by modern technology with features similar to solid crystals. In solid crystals, a band structure can be discovered from its dispersion relation; therefore, the same structure can be seen in photonic crystals as well. Furthermore, photonic crystals have forbidden band where electromagnetic waves with specific frequency cannot exist within as solid crystals have bandgaps.
Implementation Method 2
a light-transmissive conducting layer over the insulating layer and connecting to the photonic crystal structure through the aperture of the insulating layer
Implementation Method 3
electrically pumped lasers have external electricity source to produce laser beams
Implementation Method 4
an active layer having a quantum structure over the first waveguiding layer
Implementation Method 5
a first waveguiding layer over the inner surface of the substrate; a second waveguiding layer over the active layer
Implementation Method 6
the laser emitted from the band-edge lasers diffract out from a surface of the photonic crystals to achieve surface-emission
Data Source
AI summary
A laser device includes a substrate, a first waveguiding layer, an active layer, a second waveguiding layer, a contact layer, an insulating layer, a light-transmissive conducting layer, a first electrode, and a second electrode. The first waveguiding layer, the active layer, the second waveguiding layer, and the contact layer form an epitaxy structure having a first platform and a second platform. The first platform has multiple holes to form a photonic crystal structure. The insulating layer is over an upper surface and a sidewall surface of the first platform, and over an upper surface of the second platform. The sidewall surface passes through the contact layer, the second waveguiding layer, and the active layer. The light-transmissive conducting layer connects to the photonic crystal structure through an aperture of the insulating layer. The first electrode has an opening corresponding to the aperture. The second electrode is under the substrate.