Laser Light Source External Filter Narrow Line-Width
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing laser light sources with narrow spectrum line-widths require complex optical resonator structures or increased waveguide loss to prevent adjacent longitudinal mode light, which complicates the design and reduces the contraction effect of line-width with increased resonator length.
Innovation Solution
A laser light source with an optical resonator and a first optical filter positioned outside the resonator, which does not constitute part of the resonator structure, and features antireflection coating to prevent light reflection back into the resonator, allowing for a simple structure that maintains narrow spectrum line-width without increasing internal loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the length of the optical resonator is increased to contract the spectrum line-width, then the line-width contraction effect is improved, but adjacent longitudinal mode light with high intensities is generated
Solution Approach 1:
The patent divides the optical filtering function into two separate parts: an optical filter inside the resonator that provides initial mode selection, and a second optical filter outside the resonator that provides final spectral purification. This segmentation allows the resonator to be kept simple while achieving narrow line-width output by removing adjacent longitudinal modes through the external filter.
Solution Approach 2:
The patent introduces an external optical filter as an intermediary component between the resonator and the output. This intermediary element handles the task of removing adjacent longitudinal modes without requiring modification of the resonator structure itself, thus resolving the contradiction between line-width contraction and mode suppression.
2Object-generated harmful factors
If multiple-stage optical filters are provided within the optical resonator to prevent adjacent longitudinal mode light, then the harmful adjacent modes are reduced, but the waveguide loss increases and line-width contraction effect is reduced
Solution Approach 1:
The patent extracts the second optical filter from inside the resonator and places it outside. This extraction eliminates the need for multiple filtering stages within the resonator, thereby reducing waveguide loss while still achieving suppression of adjacent longitudinal modes through the external filter that does not contribute to resonator loss.
3Manufacturing precision
If the optical resonator structure is complicated to reduce line-width without increasing resonator length, then the line-width contraction is achieved, but the device complexity increases
Solution Approach 1:
The patent uses an external optical filter as a mediator to achieve narrow line-width output without complicating the resonator structure. The resonator maintains a simple design while the external filter handles the spectral selection, separating the functions of resonance and spectral purification.
Solution Approach 2:
The patent segments the spectral control function between the resonator (which provides basic mode selection) and the external optical filter (which provides precise line-width control). This segmentation allows the resonator to remain simple while achieving the desired narrow line-width through the external filtering stage.
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 enables the output of laser light with a narrow spectrum line-width while maintaining the contraction effect of increased resonator length, improving selectivity and stability of oscillation frequency without complicating the optical resonator structure or increasing internal loss.
Implementation Method 1
an optical resonator
Implementation Method 2
a first optical filter, provided outside the optical resonator
Implementation Method 3
antireflection coating is performed on the optical resonator side of the first optical filter
Data Source
AI summary
A laser light source includes an optical resonator and a first optical filter. The first optical filter is provided outside the optical resonator, and does not constitute an optical resonator structure. For example, antireflection coating is performed on the optical resonator side of the first optical filter and on a surface on the opposite side thereto, and a reflection structure in which light after passing through the first optical filter is reflected in the direction to the optical resonator is not present on an optical path of the light.