Optical Coupler Layout for Pump-Light Recycling in Fiber Amplifiers
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Solution Overview
Problem
Optical amplifiers, particularly those using erbium-doped fibers, face low pump-efficiency issues, leading to power wastage and increased heat dissipation, which is more pronounced compared to Ytterbium-doped fibers and Erbium-Ytterbium co-doped fibers.
Innovation Solution
An optical coupler design with a relative refractive-index difference of at least 0.05% between the pump-light input-output optical fibers and the inner cladding, coupled with a pump-light supply fiber fusion-spliced to the inner cladding of the main optical fiber, enhances pump-efficiency by recycling unabsorbed pump-light through a lateral coupling mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If erbium-doped fiber is used for optical amplification, then signal amplification is achieved, but pump-efficiency is low leading to power wastage and heat dissipation
Solution Approach 1:
The patent recovers unabsorbed pump light that would otherwise be wasted by guiding it back into the amplifier fiber through a coupler, allowing it to be absorbed and converted into useful signal amplification energy, thereby reducing overall power consumption and improving pump efficiency
Solution Approach 2:
The patent implements a feedback mechanism where unabsorbed pump light is redirected back into the amplifier fiber through a coupler, creating a closed-loop system that continuously recycles available pump energy until it is fully absorbed, maximizing energy utilization efficiency
2Power
If pump light power is increased to improve signal amplification, then signal light power increases, but heat dissipation increases due to low pump-efficiency
Solution Approach 1:
The patent recovers unabsorbed pump light that would otherwise be wasted by guiding it back into the amplifier fiber through a coupler, allowing it to be absorbed and converted into useful signal amplification energy, thereby reducing overall power consumption and improving pump efficiency
Solution Approach 2:
The patent enables continuous absorption of pump light by recycling unabsorbed portions back into the fiber, ensuring that the amplification process continues with maximum energy utilization until all pump light is absorbed, preventing energy waste and heat generation from unused pump power
3Loss of energy
If unabsorbed pump light is discarded, then device complexity is reduced, but pump-efficiency decreases and power is wasted
Solution Approach 1:
The patent implements a feedback mechanism where unabsorbed pump light is redirected back into the amplifier fiber through a coupler, creating a closed-loop system that continuously recycles available pump energy until it is fully absorbed, maximizing energy utilization efficiency
Solution Approach 2:
The patent employs an optical coupler that serves dual functions: it extracts signal light from the amplifier fiber and simultaneously redirects unabsorbed pump light back into the fiber, allowing a single component to perform multiple functions and reduce overall system 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
This design significantly increases pump-efficiency in optical amplifiers by effectively recycling and reusing unabsorbed pump-light, reducing power consumption and heat dissipation, thereby improving the overall performance of the optical amplifier.
Implementation Method 1
a relative refractive-index difference of an average refractive index of the pump-light input-output optical fiber in a contact region where the pump-light input-output optical fiber is in contact with the inner cladding portion with respect to a refractive index of the inner cladding portion is equal to or larger than 0.05%
Implementation Method 2
another end which is fusion-spliced to the inner cladding portion of the main optical fiber at a portion where an outer cladding portion is removed, and supplies pump-light to the main optical fiber
Implementation Method 3
erbium (Er) that serves as an optical amplifying medium and is doped in the cores
Implementation Method 4
a portion of the pump light is absorbed in the doped core of the amplifier fiber
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
An aim is to provide an optical coupler that contributes increasing pump-efficiency in an optical amplifier, and the optical amplifier. The optical amplifier includes: a main optical fiber (4a, 4Ba, 6a) that includes a core (2ba, 4aa, 4Baa, 6aa) transmitting signal light, an inner cladding portion (4ab, 4Bab, 6ab) formed around an outer periphery of the core (2ba, 4aa, 4Baa, 6ab) and having a refractive index lower than a refractive index of the core (2ba, 4aa, 4Baa, 6aa), and an outer cladding portion (4ac, 6ac) formed around an outer periphery of the inner cladding portion (4ab, 4Bab, 6ab), having a refractive index lower than the refractive index of the inner cladding portion (4ab, 4Bab, 6ab), a part of the outer cladding portion (4ac, 6ac) of which in a longitudinal direction being removed; and at least one pump-light input-output optical fiber (4b, 6b) that is fusion-spliced to the inner cladding portion (4ab, 4Bab, 6ab) of the main optical fiber (4a, 4Ba, 6a) at the portion where the outer cladding portion (4ac, 6ac) is removed, an average refractive index of which in a contact region where the pump-light input-output optical fiber (4b, 6b) is in contact with the inner cladding portion (4ab, 4Bab, 6ab) being larger than the refractive index of the inner cladding portion (4ab, 4Bab, 6ab). Pump-light propagating in the pump-light input-output optical fiber (4b, 6b) is coupled to the inner cladding portion (4ab, 4Bab, 6ab) from the contact region and propagates in the inner cladding portion (4ab, 4Bab, 6ab), or the pump-light propagating in the inner cladding portion (4ab, 4Bab, 6ab) is coupled to the pump-light input-output optical fiber (4b, 6b) from the contact region and propagates in the pump-light input-output optical fiber (4b, 6b).