VECSEL Laser Chip Phase Compensation Layer Design
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Solution Overview
Problem
Related art laser chips experience reduced output quality due to phase shifts in light resonating within the cavity caused by anti-reflection coatings and pump beam reflective layers, leading to lower modal gain and output power.
Innovation Solution
A laser chip design featuring a substrate with a distributed Bragg reflector layer, an active layer with multiple quantum wells, and an upper coating layer formed by alternately stacking layers of different refractive indices, with thicknesses corresponding to a quarter of the wavelength, to maintain phase coherence and enhance modal gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If anti-reflection coating and pump beam reflective layer are applied on active layer, then pump beam utilization is improved, but phase of resonating light is shifted causing reduced modal gain
Solution Approach 1:
A phase compensation layer is introduced as an intermediary element between the active layer and the external cavity. This layer specifically compensates for the phase shift caused by the anti-reflection coating and pump beam reflective layer, restoring phase coherence to the resonating light while preserving the optical properties of the existing coatings.
Solution Approach 2:
The refractive index and thickness of the phase compensation layer are precisely controlled to match specific optical parameters. By adjusting these parameters, the layer compensates for phase shifts and optimizes the standing wave pattern alignment with quantum well locations, thereby improving modal gain without sacrificing pump beam utilization.
2Adaptability or versatility
If additional layers are stacked on active layer, then structural functionality is enhanced, but modal gain is reduced due to phase shift
Solution Approach 1:
The phase compensation layer serves as a mediator that allows additional functional layers to be stacked on the active layer while maintaining optical performance. It compensates for phase shifts introduced by these layers, ensuring that modal gain is preserved despite the increased structural complexity.
3Reliability
If standing wave anti-node does not coincide with multiple quantum well layer, then phase coherence is maintained, but modal gain and output power are reduced
Solution Approach 1:
The phase compensation layer's thickness and refractive index are precisely engineered to adjust the standing wave pattern. This adjustment ensures that the anti-node of the standing wave coincides with the multiple quantum well layer, maximizing modal gain and output power while maintaining phase coherence through controlled parameter optimization.
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 design improves modal gain and output power by preventing phase shifts, resulting in a higher efficiency vertical external cavity surface emitting laser (VECSEL) with increased optical power.
Implementation Method 1
a distributed Bragg reflector layer
Implementation Method 2
an active layer with multiple quantum wells, and an upper coating layer formed by alternately stacking layers of different refractive indices
Implementation Method 3
an upper coating layer formed by alternately stacking layers of different refractive indices, with thicknesses corresponding to a quarter of the wavelength
Data Source
AI summary
Example embodiments may provide an increased efficiency laser chip and/or a vertical external cavity surface emitting laser (VECSEL) using the same. Example embodiment laser chips may include a substrate; a DBR (distributed Bragg reflector) layer on the substrate, an active layer on the DBR layer having multiple quantum wells excited by a pump beam to generate light, and/or an upper coating layer on the active layer by alternately stacking first and second layers each having different refractive indexes. Thicknesses of the first and second layers may be substantially equal to a quarter of a wavelength of light generated by the active layer.