VCSEL Loss Layer for Larger Current-Induced Wavelength Shift
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Solution Overview
Problem
Existing VCSELs with small active diameters exhibit a large wavelength shift for the same driving current, leading to higher current densities and reduced reliability, which is undesirable for sensor applications relying on self-mixing interference.
Innovation Solution
Incorporating a loss layer in the optical resonator that introduces additional optical and/or electrical losses, with the loss layer's optical losses exceeding the sum of the remaining regions' losses and electrical losses being at least five times higher than the rest of the resonator, to increase wavelength shift without relying on active diameter reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the active diameter of the VCSEL is reduced to increase wavelength shift, then the wavelength dependence on driving current is improved, but the current density increases which reduces reliability
Solution Approach 1:
The patent introduces a loss layer with specific optical loss properties placed at a particular location within the VCSEL structure. This loss layer creates localized optical losses that increase the wavelength dependence on driving current without requiring a reduction in active diameter, thereby maintaining reliability while achieving the desired wavelength shift for sensor applications
Solution Approach 2:
The patent modifies the optical parameters of the VCSEL by introducing a loss layer with controlled optical loss characteristics. This changes the wavelength dependence behavior of the device, enabling higher wavelength shift for a given current variation without altering the active diameter or compromising the current-density-related reliability
2Use of energy by moving object
If optical losses are reduced close to the active layer to improve efficiency, then the optical efficiency is improved, but the wavelength shift dependence on driving current is reduced
Solution Approach 1:
The loss layer is strategically positioned within the VCSEL structure to create localized optical losses in a specific region. This localized approach allows the patent to increase wavelength dependence without significantly impacting the overall optical efficiency, as the losses are confined to a specific zone rather than being distributed throughout the entire optical path
Solution Approach 2:
The patent introduces a controlled amount of optical loss through the loss layer, which is excessive compared to conventional designs but localized and optimized. This partial action approach allows the wavelength shift to be enhanced while the overall optical efficiency remains acceptable due to the targeted nature of the losses
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 solution provides a reliable VCSEL with enhanced wavelength dependence on driving current, suitable for sensor applications, by intentionally increasing optical and electrical losses to achieve a larger wavelength shift without compromising device efficiency or lifetime.
Implementation Method 1
the optical resonator further comprises a loss layer introducing optical and/or electrical losses to increase wavelength shift of the laser emission when varying the drive current
Implementation Method 2
the optical resonator further comprises a loss layer introducing optical and/or electrical losses to increase wavelength shift of the laser emission when varying the drive current
Data Source
AI summary
A Vertical Cavity Surface Emitting Laser (VCSEL) includes an optical resonator with a first reflector, a second reflector, and an active region for laser emission arranged between the first reflector and the second reflector, and an electrical contact arrangement configured to provide an electrical drive current to electrically pump the optical resonator. The optical resonator further comprises a loss layer introducing optical and electrical losses to increase wavelength shift of the laser emission when varying the drive current. The optical losses introduced by the loss layer are higher than the sum of the optical losses in remaining regions outside the active region. The electrical losses introduced by the loss layer are higher by a factor of at least 5 than the electrical losses in the remaining regions.