Raman Laser Cavity Reflectivity Enhancement
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Solution Overview
Problem
Conventional visible laser devices with linear cavities suffer from insufficient output light power, requiring high-powered incident pumping light, which is inefficient in terms of power consumption and cost.
Innovation Solution
A high-power visible light Raman laser apparatus with enhanced cavity reflectivity, utilizing a linear cavity comprising a gain medium, Raman medium, and lithium triborate (LBO) crystal, along with a double-coated output coupling mirror that effectively locks fundamental frequency and Stokes waves, converting them into visible light, thereby increasing output power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional linear cavity design is used, then device structure is simple, but output light power is insufficient
Solution Approach 1:
The output coupling mirror is segmented into multiple functional layers: a base substrate and multiple dielectric coating layers with different refractive indices. This segmentation allows each layer to contribute to the overall high reflectivity for specific wavelengths while maintaining structural feasibility and manufacturability.
Solution Approach 2:
The output coupling mirror employs composite material structure with alternating high and low refractive index dielectric layers. This composite design creates constructive interference for reflected light at target wavelengths, achieving high reflectivity for fundamental frequency and Stokes waves while allowing transmission for visible laser light.
2Power
If high-powered incident pumping light is used, then required output power is achieved, but power consumption and cost increase
Solution Approach 1:
The enhanced reflectivity of the output coupling mirror creates a feedback mechanism that recycles photons within the cavity. Fundamental frequency and Stokes waves that would otherwise be lost are reflected back into the gain medium, extending their interaction length and improving conversion efficiency to visible laser light.
Solution Approach 2:
The high reflectivity design ensures continuous recycling of fundamental frequency and Stokes waves within the optical cavity, maintaining their useful action for frequency conversion. This continuous circulation maximizes the conversion efficiency per unit of pumping power, reducing overall power consumption.
3Power
If conventional output coupling mirror is used, then device complexity is low, but reflectivity for fundamental frequency and Stokes waves is insufficient
Solution Approach 1:
The mirror design optimizes specific parameters including layer thickness, refractive index contrast, and number of dielectric layers. These parameter changes are tailored to achieve high reflectivity at fundamental frequency and Stokes wavelengths while maintaining transmission at visible laser wavelengths, resolving the contradiction between performance and complexity.
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 significantly enhances visible laser output power, reducing power consumption and costs, making it suitable for medical and industrial applications by efficiently converting pumping light into high-power visible laser light.
Implementation Method 1
The gain medium 7 receives the pumping light Lpump, and generates a first infrared base laser light Lbase1 having the wavelength of about 1106 nm through energy level conversion.
Implementation Method 2
The Raman medium 8 absorbs the first infrared basic laser light Lbase1, and generates a second infrared basic laser light Lbase2 with a wavelength of about 1176 nm.
Implementation Method 3
the LBO crystal 9 can form a visible laser light L1 with a wavelength of about 588 nanometer via second harmonic generating (SHG) process
Implementation Method 4
Since the surfaces 31/51 of the first lens 3 and the second lens 5 facing the cavity are highly reflective to the first infrared basic laser light Lbase1, the first infrared basic laser light Lbase1 is reflected back and forth in the linear cavity
Data Source
AI summary
The invention discloses a Raman laser apparatus including a linear cavity having a first direction and a second direction opposite to the first direction, the linear cavity including along the first direction: a first optical component, a gain medium, a Raman medium, a lithium triborate (LBO) crystal and a second optical component. The first optical component receives an incident pumping light in the first direction. The gain medium receives the pumping light from the first optical component, and generates a first infrared base laser having a first wavelength. The Raman medium receives the first infrared base laser, and generates a second infrared base laser having a second wavelength. The LBO crystal receives the first and the second infrared base lasers, and generates a visible laser light having a third wavelength. The second optical component is configured to allow the visible laser light to be transmitted out along the first direction.