Planar Waveguide Parasitic Oscillation Suppression
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Solution Overview
Problem
Optical fibers with a double-cladding structure using doped glass as the inner cladding emit light when the core oscillates, leading to parasitic oscillation that amplifies unwanted wavelengths, reducing the amplification factor of signal light.
Innovation Solution
A planar waveguide design incorporating a core, first inner cladding, and dielectric multilayer films on the outer claddings to transmit signal light wavelengths and reflect excitation light, preventing parasitic oscillation by controlling light transmission and reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If doped glass is used as the inner cladding in a double-cladding structure, then the structure can emit first excitation light by absorbing second excitation light, but parasitic oscillation of the core occurs and amplification factor of signal light drops
Solution Approach 1:
The patent extracts the light-emitting function from the inner cladding by replacing doped glass with a transparent material. The inner cladding no longer emits light but instead guides excitation light to the signal light propagation path, eliminating parasitic oscillation while maintaining the double-cladding structure's efficiency.
Solution Approach 2:
Instead of having the inner cladding emit light (traditional approach), the patent inverts the approach by making the inner cladding transparent and using it to guide excitation light directly to the signal light path. This inversion eliminates the harmful light emission from the inner cladding while maintaining efficient energy transfer.
2Device complexity
If the inner cladding emits first excitation light, then a separate light source for introducing first excitation light is not needed, but parasitic oscillation occurs and unwanted wavelengths are amplified
Solution Approach 1:
The patent removes the light-emitting capability from the inner cladding material itself, replacing it with a transparent material. The excitation light is introduced from an external source and guided through the transparent inner cladding, separating the light guidance function from the light emission function.
Solution Approach 2:
The transparent inner cladding acts as an intermediary that guides excitation light from the outer cladding to the signal light propagation path without emitting light itself. This mediator role eliminates parasitic oscillation while maintaining efficient energy transfer to the signal light.
3Power
If the core oscillates and emits light, then amplification of signal light occurs, but unwanted wavelengths are also amplified reducing signal light amplification factor
Solution Approach 1:
The patent extracts the light-emitting function from the inner cladding, preventing it from generating unwanted wavelengths. Only the core amplifies signal light at the desired wavelength, while the transparent inner cladding merely guides excitation light without adding spectral contamination.
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 planar waveguide effectively amplifies signal light while preventing parasitic oscillation, enhancing the amplification factor and reducing unwanted light amplification.
Implementation Method 1
a core (11) for amplifying signal light by absorbing first excitation light and forming a population inversion
Implementation Method 2
a first inner cladding (12) for absorbing second excitation light and emitting first excitation light by forming a population inversion
Implementation Method 3
emits the first excitation light by absorbing second excitation light and forming a population inversion
Implementation Method 4
a first outer cladding (13) attached to one plane of the first inner cladding (12), and a second outer cladding (14) attached to the other plane of the first inner cladding (12), each having a smaller refractive index than the first inner cladding, and totally reflecting the first excitation light
Implementation Method 5
a first dielectric multilayer film (15) for transmitting light having a wavelength band including the wavelength of signal light and reflecting first excitation light
Implementation Method 6
transmitting light having a wavelength band including the wavelength of signal light and reflecting the first excitation light
Data Source
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AI summary
Included are: a first dielectric multilayer film (15) for transmitting a wavelength band including a wavelength of signal light (2) and reflecting first excitation light (4), the first dielectric multilayer film (15) being disposed on one of two end surfaces of a core (11), a first inner cladding (12), a first outer cladding (13), and a second outer cladding (14) ; and a second dielectric multilayer film (12) for transmitting a wavelength band including the wavelength of the signal light (2) and reflecting the first excitation light (4), the second dielectric multilayer film (12) being disposed on the other one of the two end surfaces.