Semiconductor Laser Waveguide Layout for Unidirectional Light Output
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Solution Overview
Problem
Conventional semiconductor lasers experience optical power loss due to symmetrical emission structures, where 50% of optical power is lost as light is output to both sides, hindering efficient information transmission.
Innovation Solution
A semiconductor laser design featuring a first and second optical waveguide with periodically modulated refractive index, a confinement portion, and a third reflection unit, where the second optical waveguide is optically coupled with the confinement portion, allowing laser output only to the side of the second reflection unit, thereby preventing power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a symmetrical emission structure is used, then light can be output to both front side and rear side, but optical power is lost because 50% of the power is output to the rear side which is unnecessary for unidirectional information transmission
Solution Approach 1:
The patent introduces asymmetry into the symmetrical emission structure by adding a third reflection unit specifically on the rear side. This creates an asymmetric configuration where the front side has only one reflection unit while the rear side has two reflection units (second and third), enabling directional control of light emission and preventing unnecessary rear-side output that causes power loss
2Loss of energy
If a third reflection unit is added to the rear side, then optical power loss is prevented by blocking rear-side emission, but device complexity increases due to additional structural components
Solution Approach 1:
The patent merges the third reflection unit with the second optical waveguide, forming an integrated structure where the reflection unit is disposed on the rear side of the second optical waveguide. This merging approach reduces structural complexity compared to adding a completely separate component, while still achieving the function of blocking rear-side emission and preventing optical power loss
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 design achieves high light extraction efficiency, with front-side light extraction efficiency ranging from 80% to 90%, breaking the 50% limit of conventional symmetrical emission structures and ensuring single mode oscillation with a wide free spectral range.
Implementation Method 1
an optical waveguide structure in which a single mode oscillation is enabled by causing Bragg reflection by subjecting an optical waveguide to periodic refractive index modulation to resonate only a specific wavelength component
Implementation Method 2
the extraction optical waveguide having an appropriate equivalent refractive index is arranged in the vicinity of the optical waveguide type lasers to be optically coupled with the laser resonator, and direct light extraction from the laser resonator to the extraction optical waveguide can be realized
Implementation Method 3
a Fabry-Perot optical resonator is configured by the first reflection unit, the confinement portion, and the second reflection unit
Data Source
AI summary
A semiconductor laser includes a first optical waveguide including a first reflection unit and a second reflection unit, and a confinement portion. The first reflection unit and the second reflection unit are waveguide type reflection units each having a structure in which the refractive index is periodically modulated. The first reflection unit, the confinement portion, and the second reflection unit constitute a Fabry-Perot type optical resonator. The semiconductor laser also includes a second optical waveguide disposed along a first optical waveguide to extend from the confinement portion to the second reflection unit side. The second optical waveguide serves as an extraction optical waveguide. Further, a third reflection unit formed continuously with the second optical waveguide is provided at a location corresponding to the first reflection unit.