Interference Filter Surface Emitting Laser Wavelength Control
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Solution Overview
Problem
Surface emitting semiconductor lasers face challenges in stabilizing emission wavelength and controlling spectral width, particularly in high-quality factor resonators, due to the high requirements for beam divergence and alignment accuracy imposed by etalons and bifringent filters.
Innovation Solution
A surface emitting semiconductor laser with a laser resonator containing an interference filter formed from a dielectric layer system, which allows for variation of wavelength and spectral width by adjusting the angle of incidence, reducing production and alignment complexity and offering lower loss compared to traditional etalons and bifringent filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If etalons or bifringent filters are used for wavelength stabilization, then wavelength control is achieved, but beam divergence requirements and alignment accuracy requirements increase significantly
Solution Approach 1:
The patent changes the operational parameters of the interference filter by varying the angle of incidence of the laser radiation. This allows wavelength tuning without requiring precise alignment of the filter itself, as the wavelength selection is achieved through parameter variation rather than mechanical alignment precision
Solution Approach 2:
The patent replaces the mechanical alignment system required by etalons and bifringent filters with an optical interference filter that achieves wavelength selection through dielectric layer interference. This substitution eliminates the need for complex mechanical alignment mechanisms while maintaining wavelength control precision
2Reliability
If etalons or bifringent filters are used for wavelength selection, then wavelength stabilization is achieved, but production cost and alignment outlay increase
Solution Approach 1:
The patent employs a dielectric interference filter that can be manufactured more cost-effectively than etalons or bifringent filters. The filter consists of multiple dielectric layers that can be produced using standard thin-film deposition techniques, reducing both material costs and manufacturing complexity while maintaining wavelength stabilization capability
Solution Approach 2:
The interference filter is constructed from composite dielectric layers with different refractive indices, creating a multi-layer structure that achieves wavelength selection through constructive and destructive interference. This composite approach allows for cost-effective manufacturing while providing reliable wavelength stabilization
3Ease of manufacture
If conventional dielectric interference filters are used in high quality factor resonators, then production is simplified, but transmission loss increases due to maximum transmission less than 99%
Solution Approach 1:
The patent optimizes the parameters of the interference filter, specifically the thickness and refractive index of the dielectric layers, to achieve maximum transmission greater than 99.8%. By carefully tuning these parameters, the filter maintains its wavelength selection capability while minimizing transmission loss in the high quality factor resonator environment
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 dielectric interference filter provides effective wavelength stabilization and spectral control with reduced beam divergence requirements, achieving transmission greater than 99.8% and enabling efficient operation within a narrowband amplification spectrum.
Implementation Method 1
an interference filter which is formed from an interference layer system comprising a plurality of dielectric layers
Implementation Method 2
The wavelength and the spectral width of the laser emission can be varied within the amplification spectrum of the laser by means of the design and/or the angle of incidence at which the laser radiation impinges on the interference filter
Data Source
AI summary
A surface emitting semiconductor laser includes a semiconductor chip (1), which emits radiation (12) and contains a first resonator mirror (3). A second resonator mirror (6) is arranged outside the semiconductor chip (1). The first resonator mirror (3) and the second resonator mirror (6) form a laser resonator for the radiation (12) emitted by the semiconductor chip (1). The laser resonator contains an interference filter (9, 17), which is formed from an interference layer system comprising a plurality of dielectric layers.